build(www): 添加 Drone CI 流水线配置
- 新增 .drone.yml 文件用于定义 CI/CD 流程 - 配置了基于 Docker 的部署步骤 - 设置了工作区和卷映射以支持持久化数据 - 添加了构建准备阶段和 Docker 部署阶段 - 定义了环境变量和代理设置 - 配置了 artifacts 目录的处理逻辑 - 添加了 timezone 映射以确保时间同步 - 设置了 docker.sock 映射以支持 Docker in Docker
This commit is contained in:
196
public/blogs/database/redis/redis.html
Normal file
196
public/blogs/database/redis/redis.html
Normal file
File diff suppressed because one or more lines are too long
152
public/blogs/frontend/promise.html
Normal file
152
public/blogs/frontend/promise.html
Normal file
File diff suppressed because one or more lines are too long
205
public/blogs/frontend/typescript.html
Normal file
205
public/blogs/frontend/typescript.html
Normal file
File diff suppressed because one or more lines are too long
343
public/blogs/java/java8/java8-1.html
Normal file
343
public/blogs/java/java8/java8-1.html
Normal file
File diff suppressed because one or more lines are too long
555
public/blogs/java/java8/java8-2.html
Normal file
555
public/blogs/java/java8/java8-2.html
Normal file
@@ -0,0 +1,555 @@
|
||||
<!DOCTYPE html>
|
||||
<html lang="zh-CN">
|
||||
<head>
|
||||
<meta charset="utf-8">
|
||||
<meta name="viewport" content="width=device-width,initial-scale=1">
|
||||
<title>JDK8 特性（二） | ZhuHJay Blog</title>
|
||||
<meta name="generator" content="VuePress 1.9.7">
|
||||
<link rel="icon" href="/favicon.ico">
|
||||
<meta name="description" content="my blog">
|
||||
<meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no">
|
||||
|
||||
<link rel="preload" href="/assets/css/0.styles.93f9cd2e.css" as="style"><link rel="preload" href="/assets/js/app.049e1b5b.js" as="script"><link rel="preload" href="/assets/js/3.ff0e945d.js" as="script"><link rel="preload" href="/assets/js/1.1ced4111.js" as="script"><link rel="preload" href="/assets/js/15.bd05cf61.js" as="script"><link rel="prefetch" href="/assets/js/10.21e2f029.js"><link rel="prefetch" href="/assets/js/11.18770288.js"><link rel="prefetch" href="/assets/js/12.588a1dd8.js"><link rel="prefetch" href="/assets/js/13.e66c15d0.js"><link rel="prefetch" href="/assets/js/14.141a3334.js"><link rel="prefetch" href="/assets/js/16.346083d6.js"><link rel="prefetch" href="/assets/js/17.382f52f1.js"><link rel="prefetch" href="/assets/js/18.a55369bc.js"><link rel="prefetch" href="/assets/js/19.a2a264ee.js"><link rel="prefetch" href="/assets/js/20.c6871f96.js"><link rel="prefetch" href="/assets/js/21.2956f057.js"><link rel="prefetch" href="/assets/js/4.581595e5.js"><link rel="prefetch" href="/assets/js/5.55d6cfd7.js"><link rel="prefetch" href="/assets/js/6.9619dc5e.js"><link rel="prefetch" href="/assets/js/7.d2b7a379.js"><link rel="prefetch" href="/assets/js/8.9f502ca9.js"><link rel="prefetch" href="/assets/js/9.ec0bd674.js">
|
||||
<link rel="stylesheet" href="/assets/css/0.styles.93f9cd2e.css">
|
||||
</head>
|
||||
<body>
|
||||
<div id="app" data-server-rendered="true"><div class="theme-container" data-v-7dd95ae2><div data-v-7dd95ae2><div class="password-shadow password-wrapper-out" style="display:none;" data-v-59e6cb88 data-v-7dd95ae2 data-v-7dd95ae2><h3 class="title" data-v-59e6cb88>ZhuHJay Blog</h3> <p class="description" data-v-59e6cb88>my blog</p> <label id="box" class="inputBox" data-v-59e6cb88><input type="password" value="" data-v-59e6cb88> <span data-v-59e6cb88>Konck! Knock!</span> <button data-v-59e6cb88>OK</button></label> <div class="footer" data-v-59e6cb88><span data-v-59e6cb88><i class="iconfont reco-theme" data-v-59e6cb88></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-59e6cb88>vuePress-theme-reco</a></span> <span data-v-59e6cb88><i class="iconfont reco-copyright" data-v-59e6cb88></i> <a data-v-59e6cb88><span data-v-59e6cb88>ZhuHJay</span>
|
||||
|
||||
<span data-v-59e6cb88>2021 - </span>
|
||||
2025
|
||||
</a></span></div></div> <div class="hide" data-v-7dd95ae2><header class="navbar" data-v-7dd95ae2><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><img src="/logo.png" alt="ZhuHJay Blog" class="logo"> <span class="site-name">ZhuHJay Blog</span></a> <div class="links"><div class="color-picker"><a class="color-button"><i class="iconfont reco-color"></i></a> <div class="color-picker-menu" style="display:none;"><div class="mode-options"><h4 class="title">Choose mode</h4> <ul class="color-mode-options"><li class="dark">dark</li><li class="auto active">auto</li><li class="light">light</li></ul></div></div></div> <div class="search-box"><i class="iconfont reco-search"></i> <input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><a href="/" class="nav-link"><i class="iconfont reco-home"></i>
|
||||
首页
|
||||
</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title"><i class="iconfont reco-category"></i>
|
||||
分类
|
||||
</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/categories/Java/" class="nav-link"><i class="undefined"></i>
|
||||
Java
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/NoSQL/" class="nav-link"><i class="undefined"></i>
|
||||
NoSQL
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/JavaScript/" class="nav-link"><i class="undefined"></i>
|
||||
JavaScript
|
||||
</a></li></ul></div></div><div class="nav-item"><a href="/tag/" class="nav-link"><i class="iconfont reco-tag"></i>
|
||||
标签
|
||||
</a></div><div class="nav-item"><a href="https://gitee.com/ZhuHJay" target="_blank" rel="noopener noreferrer" class="nav-link external"><i class="iconfont reco-mayun"></i>
|
||||
码云
|
||||
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav></div></header> <div class="sidebar-mask" data-v-7dd95ae2></div> <aside class="sidebar" data-v-7dd95ae2><div class="personal-info-wrapper" data-v-1fad0c41 data-v-7dd95ae2><img src="/avatar.png" alt="author-avatar" class="personal-img" data-v-1fad0c41> <h3 class="name" data-v-1fad0c41>
|
||||
ZhuHJay
|
||||
</h3> <div class="num" data-v-1fad0c41><div data-v-1fad0c41><h3 data-v-1fad0c41>11</h3> <h6 data-v-1fad0c41>文章</h6></div> <div data-v-1fad0c41><h3 data-v-1fad0c41>5</h3> <h6 data-v-1fad0c41>标签</h6></div></div> <ul class="social-links" data-v-1fad0c41></ul> <hr data-v-1fad0c41></div> <nav class="nav-links"><div class="nav-item"><a href="/" class="nav-link"><i class="iconfont reco-home"></i>
|
||||
首页
|
||||
</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title"><i class="iconfont reco-category"></i>
|
||||
分类
|
||||
</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/categories/Java/" class="nav-link"><i class="undefined"></i>
|
||||
Java
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/NoSQL/" class="nav-link"><i class="undefined"></i>
|
||||
NoSQL
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/JavaScript/" class="nav-link"><i class="undefined"></i>
|
||||
JavaScript
|
||||
</a></li></ul></div></div><div class="nav-item"><a href="/tag/" class="nav-link"><i class="iconfont reco-tag"></i>
|
||||
标签
|
||||
</a></div><div class="nav-item"><a href="https://gitee.com/ZhuHJay" target="_blank" rel="noopener noreferrer" class="nav-link external"><i class="iconfont reco-mayun"></i>
|
||||
码云
|
||||
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav> <ul class="sidebar-links"><li><a href="/blogs/java/java8/java8-1.html" class="sidebar-link">JDK8 特性（一）</a></li><li><a href="/blogs/java/java8/java8-2.html" aria-current="page" class="active sidebar-link">JDK8 特性（二）</a></li><li><a href="/blogs/java/java8/java8-3.html" class="sidebar-link">JDK8 特性（三）</a></li><li><a href="/blogs/java/java8/java8-4.html" class="sidebar-link">JDK8 特性（四）</a></li></ul> </aside> <div class="password-shadow password-wrapper-in" style="display:none;" data-v-59e6cb88 data-v-7dd95ae2><h3 class="title" data-v-59e6cb88>JDK8 特性（二）</h3> <!----> <label id="box" class="inputBox" data-v-59e6cb88><input type="password" value="" data-v-59e6cb88> <span data-v-59e6cb88>Konck! Knock!</span> <button data-v-59e6cb88>OK</button></label> <div class="footer" data-v-59e6cb88><span data-v-59e6cb88><i class="iconfont reco-theme" data-v-59e6cb88></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-59e6cb88>vuePress-theme-reco</a></span> <span data-v-59e6cb88><i class="iconfont reco-copyright" data-v-59e6cb88></i> <a data-v-59e6cb88><span data-v-59e6cb88>ZhuHJay</span>
|
||||
|
||||
<span data-v-59e6cb88>2021 - </span>
|
||||
2025
|
||||
</a></span></div></div> <div data-v-7dd95ae2><div data-v-7dd95ae2><main class="page"><section style="display:;"><div class="page-title"><h1 class="title">JDK8 特性（二）</h1> <div data-v-8a445198><i class="iconfont reco-account" data-v-8a445198><span data-v-8a445198>ZhuHJay</span></i> <i class="iconfont reco-date" data-v-8a445198><span data-v-8a445198>2022/5/24</span></i> <!----> <i class="tags iconfont reco-tag" data-v-8a445198><span class="tag-item" data-v-8a445198>JDK8</span></i></div></div> <div class="theme-reco-content content__default"><h2 id="_1-stream流"><a href="#_1-stream流" class="header-anchor">#</a> 1 Stream流</h2> <h3 id="_1-1-集合处理数据的弊端"><a href="#_1-1-集合处理数据的弊端" class="header-anchor">#</a> 1.1 集合处理数据的弊端</h3> <ul><li><p>案例引入:</p> <ol><li>首先筛选所有姓张的人；</li> <li>然后筛选名字有三个字的人；</li> <li>最后进行对结果进行打印输出。</li></ol></li> <li><p>传统实现</p></li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamDemo</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 1. 首先筛选所有姓张的人；</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> zhangList <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token class-name">String</span> name <span class="token operator">:</span> list<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">if</span><span class="token punctuation">(</span>name<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"张"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
zhangList<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token comment">// 2. 然后筛选名字有三个字的人；</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> threeList <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token class-name">String</span> name <span class="token operator">:</span> zhangList<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">if</span><span class="token punctuation">(</span>name<span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
threeList<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token comment">// 3. 最后进行对结果进行打印输出。</span>
|
||||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token class-name">String</span> name <span class="token operator">:</span> threeList<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>name<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br></div></div><ul><li>Stream流式实现</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamDemo</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 1. 首先筛选所有姓张的人; 2. 然后筛选名字有三个字的人; 3. 最后进行对结果进行打印输出</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>str <span class="token operator">-></span> str<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"张"</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>str <span class="token operator">-></span> str<span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">3</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><h3 id="_1-2-stream流式思想概述"><a href="#_1-2-stream流式思想概述" class="header-anchor">#</a> 1.2 Stream流式思想概述</h3> <p><strong>注意：Stream和IO流(InputStream/OutputStream)没有任何关系，请暂时忘记对传统IO流的固有印象</strong>！</p> <p>Stream流式思想类似于工厂车间的“生产流水线”，Stream流不是一种数据结构，不保存数据，而是对数据进行加工处理。Stream可以看作是流水线上的一个工序。在流水线上，通过多个工序让一个原材料加工成一个商品。</p> <p><img src="/java8/Stream%E6%B5%81%E5%BC%8F%E6%80%9D%E6%83%B3.png" alt=""></p> <p><img src="/java8/Stream%E6%B5%81%E5%BC%8F%E6%80%9D%E6%83%B31.png" alt=""></p> <p>Stream API能让我们快速完成许多复杂的操作，如筛选、切片、映射、查找、去除重复，统计，匹配和归约。</p> <h3 id="_1-3-获取stream流的两种方式"><a href="#_1-3-获取stream流的两种方式" class="header-anchor">#</a> 1.3 获取Stream流的两种方式</h3> <ul><li>方式一
|
||||
<ul><li>Collection集合接口中有默认方法<code>default Stream<E> stream(){...}</code></li> <li>也就是说实现该接口的集合类都可以直接调用stream()方法获取流对象</li></ul></li> <li>方式二
|
||||
<ul><li>Stream中的静态方法<code>static<T> Stream<T> of(T t){...}</code></li> <li>可以调用该方法获取流对象</li></ul></li></ul> <h3 id="_1-4-了解stream流的常用方法和注意事项"><a href="#_1-4-了解stream流的常用方法和注意事项" class="header-anchor">#</a> 1.4 了解Stream流的常用方法和注意事项</h3> <ul><li>Stream常用方法</li></ul> <table><thead><tr><th>方法名</th> <th>方法作用</th> <th>返回值类型</th> <th>方法种类</th></tr></thead> <tbody><tr><td>count</td> <td>统计个数</td> <td>long</td> <td>终结</td></tr> <tr><td>forEach</td> <td>逐一处理</td> <td>void</td> <td>终结</td></tr> <tr><td>filter</td> <td>过滤</td> <td>Stream</td> <td>函数拼接</td></tr> <tr><td>limit</td> <td>取用前几个</td> <td>Stream</td> <td>函数拼接</td></tr> <tr><td>skip</td> <td>跳过前几个</td> <td>Stream</td> <td>函数拼接</td></tr> <tr><td>map</td> <td>映射</td> <td>Stream</td> <td>函数拼接</td></tr> <tr><td>concat</td> <td>组合</td> <td>Stream</td> <td>函数拼接</td></tr></tbody></table> <ul><li><p>终结方法：返回值类型不再是 Stream 类型的方法，不再支持链式调用。</p></li> <li><p>非终结方法：返回值类型仍然是 Stream 类型的方法，支持链式调用。（除了终结方法外，其余方法均为非终结方法。）</p></li> <li><p>Stream注意事项</p> <ol><li>Stream只能操作一次</li> <li>Stream方法返回的是新的流</li> <li>Stream不调用终结方法，中间的操作不会执行</li></ol></li></ul> <h4 id="foreach"><a href="#foreach" class="header-anchor">#</a> forEach</h4> <ul><li>forEach用来遍历流中的数据 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>void forEach(Consumer&lt;? super T> action);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>该方法接收一个 Consumer 接口函数，会将每一个流元素交给该函数进行处理。</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h4 id="count"><a href="#count" class="header-anchor">#</a> count</h4> <ul><li>count方法来统计其中的元素个数 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>long count();
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>该方法返回一个long值代表元素个数。基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">count</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">count</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h4 id="filter"><a href="#filter" class="header-anchor">#</a> filter</h4> <ul><li>filter用于过滤数据，返回符合过滤条件的数据 -> 非终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Stream&lt;T> filter(Predicate&lt;? super T> predicate);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li><p><img src="/java8/filter.png" alt=""></p></li> <li><p>该接口接收一个 Predicate 函数式接口参数(可以是一个Lambda或方法引用)作为筛选条件。</p></li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">filter</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 计算名字长度为3的人数</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>name <span class="token operator">-></span> name<span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">count</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h4 id="limit"><a href="#limit" class="header-anchor">#</a> limit</h4> <ul><li>limit 方法可以对流进行截取，只取用前n个 -> 非终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Stream&lt;T> limit(long maxSize);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>参数是一个long型，如果集合当前长度大于参数则进行截取。否则不进行操作</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">limit</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">limit</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h4 id="skip"><a href="#skip" class="header-anchor">#</a> skip</h4> <ul><li>如果希望跳过前几个元素，可以使用 skip 方法获取一个截取之后的新流 -> 非终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Stream&lt;T> skip(long n);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>如果流的当前长度大于n，则跳过前n个; 否则将会得到一个长度为0的空流。</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">skip</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">skip</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br></div></div><h4 id="map"><a href="#map" class="header-anchor">#</a> map</h4> <ul><li>如果需要将流中的元素映射到另一个流中，可以使用 map 方法 -> 非终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>&lt;R> Stream&lt;R> map(Function&lt;? super T, ? extends R> mapper);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>该接口需要一个 Function 函数式接口参数，可以将当前流中的T类型数据转换为另一种R类型的流</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">map</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 类型增强</span>
|
||||
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>name <span class="token operator">-></span> <span class="token string">"name: "</span> <span class="token operator">+</span> name<span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div><h4 id="sorted"><a href="#sorted" class="header-anchor">#</a> sorted</h4> <ul><li>如果需要将数据排序，可以使用 sorted 方法。 -> 非终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Stream&lt;T> sorted(); // 根据元素的自然顺序排序
|
||||
Stream&lt;T> sorted(Comparator&lt;? super T> comparator); // 自定义比较器排序
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><ul><li>该方法可以有两种不同地排序实现</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">sorted</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 默认自然序</span>
|
||||
<span class="token punctuation">.</span><span class="token function">sorted</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 执行比较器进行排序</span>
|
||||
<span class="token punctuation">.</span><span class="token function">sorted</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">(</span>o1<span class="token punctuation">,</span> o2<span class="token punctuation">)</span> <span class="token operator">-></span> o1<span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> o2<span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br></div></div><h4 id="distinct"><a href="#distinct" class="header-anchor">#</a> distinct</h4> <ul><li>如果需要去除重复数据，可以使用 distinct 方法 -> 非终结方法
|
||||
<ul><li>自定义类型是根据对象的 hashCode 和 equals 来去除重复元素的</li></ul></li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Stream&lt;T> distinct();
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">distinct</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span><span class="token string">"迪丽热巴"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span><span class="token string">"张无忌"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">distinct</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div><h4 id="match"><a href="#match" class="header-anchor">#</a> match</h4> <ul><li>如果需要判断数据是否匹配指定的条件，可以使用 Match 相关方法 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>boolean anyMatch(Predicate&lt;? super T> predicate);
|
||||
boolean allMatch(Predicate&lt;? super T> predicate);
|
||||
boolean noneMatch(Predicate&lt;? super T> predicate);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br></div></div><ul><li>基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">match</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// allMatch 所有元素都需要满足</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">allMatch</span><span class="token punctuation">(</span>name <span class="token operator">-></span> name<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"张"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// anyMatch 如果有元素满足即可</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">anyMatch</span><span class="token punctuation">(</span>name <span class="token operator">-></span> name<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"张"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// noneMatch 所有元素都不满足</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">noneMatch</span><span class="token punctuation">(</span>name <span class="token operator">-></span> name<span class="token punctuation">.</span><span class="token function">contains</span><span class="token punctuation">(</span><span class="token string">"男"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br></div></div><h4 id="find"><a href="#find" class="header-anchor">#</a> find</h4> <ul><li>如果需要找到某些数据，可以使用 find 相关方法 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Optional&lt;T> findFirst();
|
||||
Optional&lt;T> findAny();
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><ul><li>基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> list<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">before</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>list<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"周芷若"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"赵敏"</span><span class="token punctuation">,</span> <span class="token string">"张强"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">find</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 都是获取第一个元素</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> optional <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">findAny</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> optional1 <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">findFirst</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>optional<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>optional1<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div><h4 id="max-min"><a href="#max-min" class="header-anchor">#</a> max && min</h4> <ul><li>如果需要获取最大和最小值，可以使用 max 和 min 方法 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Optional&lt;T> max(Comparator&lt;? super T> comparator);
|
||||
Optional&lt;T> min(Comparator&lt;? super T> comparator);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><ul><li>基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">min_max</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 传入一个比较器, 排序完后获取最后一个</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> max <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">max</span><span class="token punctuation">(</span><span class="token punctuation">(</span>o1<span class="token punctuation">,</span> o2<span class="token punctuation">)</span> <span class="token operator">-></span> o1 <span class="token operator">-</span> o2<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>max<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 传入一个比较器, 排序完后获取第一个</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> min <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">7</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">min</span><span class="token punctuation">(</span><span class="token punctuation">(</span>o1<span class="token punctuation">,</span> o2<span class="token punctuation">)</span> <span class="token operator">-></span> o1 <span class="token operator">-</span> o2<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>min<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br></div></div><h4 id="reduce"><a href="#reduce" class="header-anchor">#</a> reduce</h4> <ul><li>如果需要将所有数据归纳得到一个数据，可以使用 reduce 方法 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>T reduce(T identity, BinaryOperator&lt;T> accumulator);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">reduce</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">Integer</span> reduce <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">9</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// T identity: 默认值</span>
|
||||
<span class="token comment">// BinaryOperator<T> accumulator: 对数据的处理方式</span>
|
||||
<span class="token comment">// 获取最大值, 初始值为0</span>
|
||||
<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token class-name">Integer</span><span class="token operator">::</span><span class="token function">max</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>reduce<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
reduce <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token number">4</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">9</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// T identity: 默认值</span>
|
||||
<span class="token comment">// BinaryOperator<T> accumulator: 对数据的处理方式</span>
|
||||
<span class="token comment">// 获取加和结果, 初始值为0</span>
|
||||
<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token class-name">Integer</span><span class="token operator">::</span><span class="token function">sum</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>reduce<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br></div></div><p><img src="/java8/reduce%E6%89%A7%E8%A1%8C%E6%B5%81%E7%A8%8B.png" alt=""></p> <h4 id="map-reduce结合"><a href="#map-reduce结合" class="header-anchor">#</a> map && reduce结合</h4> <ul><li>使用案例</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">reduceAndMap</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 获取最大年龄</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> maxAge <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">,</span> <span class="token number">20</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"王五"</span><span class="token punctuation">,</span> <span class="token number">17</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小红"</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小明"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getAge</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token class-name">Integer</span><span class="token operator">::</span><span class="token function">max</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>maxAge<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 获取年龄总和</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> totalAge <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"王五"</span><span class="token punctuation">,</span> <span class="token number">17</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小红"</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小明"</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getAge</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token class-name">Integer</span><span class="token operator">::</span><span class="token function">sum</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>totalAge<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br></div></div><h4 id="maptoint"><a href="#maptoint" class="header-anchor">#</a> mapToInt</h4> <ul><li>如果需要将Stream中的Integer类型数据转成int类型，可以使用 mapToInt 方法 -> 终结方法</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>IntStream mapToInt(ToIntFunction&lt;? super T> mapper);
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li><p><img src="/java8/filter.png" alt=""></p></li> <li><p>该接口需要一个 Function 函数式接口参数，可以将当前流中的T类型数据转换为另一种R类型的流</p></li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">mapToInt</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// Integer占用的内存比int多, 在Stream流中会自动拆箱装箱</span>
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> stream <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">2</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">// 将Integer类型转换为int类型, 可以节省空间</span>
|
||||
<span class="token class-name">IntStream</span> intStream <span class="token operator">=</span> stream
|
||||
<span class="token punctuation">.</span><span class="token function">mapToInt</span><span class="token punctuation">(</span><span class="token class-name">Integer</span><span class="token operator">::</span><span class="token function">intValue</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br></div></div><h4 id="concat"><a href="#concat" class="header-anchor">#</a> concat</h4> <ul><li>如果有两个流，希望合并成为一个流，那么可以使用 Stream 接口的静态方法 concat -> 终结方法
|
||||
<ul><li>这是一个静态方法，与 <code>java.lang.String</code> 当中的 concat 方法是不同的</li></ul></li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>static &lt;T> Stream&lt;T> concat(Stream&lt;? extends T> a, Stream&lt;? extends T> b){...}
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br></div></div><ul><li>基本使用</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">concat</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> streamA <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> streamB <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">// 将以上流合并, 合并的流就不能够继续操作了</span>
|
||||
<span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>streamA<span class="token punctuation">,</span> streamB<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br></div></div><h3 id="_1-5-stream综合案例"><a href="#_1-5-stream综合案例" class="header-anchor">#</a> 1.5 Stream综合案例</h3> <ul><li>现在有两个 ArrayList 集合存储队伍当中的多个成员姓名，要求使用Stream实现若干操作步骤：
|
||||
<ol><li>第一个队伍只要名字为3个字的成员姓名；</li> <li>第一个队伍筛选之后只要前3个人；</li> <li>第二个队伍只要姓张的成员姓名；</li> <li>第二个队伍筛选之后不要前2个人；</li> <li>将两个队伍合并为一个队伍；</li> <li>根据姓名创建 Person 对象；</li> <li>打印整个队伍的Person对象信息。</li></ol></li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamCaseDemo</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> one <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> two <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>one<span class="token punctuation">,</span> <span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token string">"宋远桥"</span><span class="token punctuation">,</span> <span class="token string">"苏星河"</span><span class="token punctuation">,</span> <span class="token string">"老子"</span><span class="token punctuation">,</span> <span class="token string">"庄子"</span><span class="token punctuation">,</span> <span class="token string">"孙子"</span><span class="token punctuation">,</span> <span class="token string">"洪七公"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">addAll</span><span class="token punctuation">(</span>two<span class="token punctuation">,</span> <span class="token string">"古力娜扎"</span><span class="token punctuation">,</span> <span class="token string">"张无忌"</span><span class="token punctuation">,</span> <span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token string">"赵丽颖"</span><span class="token punctuation">,</span> <span class="token string">"张二狗"</span><span class="token punctuation">,</span> <span class="token string">"张天爱"</span><span class="token punctuation">,</span> <span class="token string">"张三"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> streamOne <span class="token operator">=</span> one<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 1. 第一个队伍只要名字为3个字的成员姓名</span>
|
||||
<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>name <span class="token operator">-></span> name<span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">==</span> <span class="token number">3</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 2. 第一个队伍筛选之后只要前3个人</span>
|
||||
<span class="token punctuation">.</span><span class="token function">limit</span><span class="token punctuation">(</span><span class="token number">3</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> streamTwo <span class="token operator">=</span> two<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 3. 第二个队伍只要姓张的成员姓名</span>
|
||||
<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>name <span class="token operator">-></span> name<span class="token punctuation">.</span><span class="token function">startsWith</span><span class="token punctuation">(</span><span class="token string">"张"</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 4. 第二个队伍筛选之后不要前2个人</span>
|
||||
<span class="token punctuation">.</span><span class="token function">skip</span><span class="token punctuation">(</span><span class="token number">2</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">// 5. 将两个队伍合并为一个队伍</span>
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">String</span><span class="token punctuation">></span></span> stream <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">concat</span><span class="token punctuation">(</span>streamOne<span class="token punctuation">,</span> streamTwo<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">// 6. 根据姓名创建 Person 对象</span>
|
||||
stream<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token keyword">new</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 7. 打印整个队伍的Person对象信息</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br></div></div><h3 id="_1-6-收集stream流中的结果"><a href="#_1-6-收集stream流中的结果" class="header-anchor">#</a> 1.6 收集Stream流中的结果</h3> <ul><li>对流操作完成之后，如果需要将流的结果保存到数组或集合中，可以收集流中的数据</li></ul> <h4 id="收集结果到集合中"><a href="#收集结果到集合中" class="header-anchor">#</a> 收集结果到集合中</h4> <ul><li>Stream流提供 collect 方法，其参数需要一个<code>java.util.stream.Collector<T,A, R></code>接口对象来指定收集到哪种集合中。<code>java.util.stream.Collectors</code>类提供一些方法，可以作为Collector`接口的实例：
|
||||
<ul><li><code>public static <T> Collector<T, ?, List<T>> toList()</code>: 转换为 List 集合</li> <li><code>public static <T> Collector<T, ?, Set<T>> toSet()</code>: 转换为 Set 集合</li> <li><code>public static <T, C extends Collection<T>> Collector<T, ?, C> toCollection(Supplier<C> collectionFactory)</code>: 收集到指定的集合中</li></ul></li></ul> <h4 id="收集结果到数组中"><a href="#收集结果到数组中" class="header-anchor">#</a> 收集结果到数组中</h4> <ul><li>Stream提供 toArray 方法来将结果放到一个数组中</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>Object[] toArray(); // 返回Object数组
|
||||
&lt;A> A[] toArray(IntFunction&lt;A[]> generator); // 返回指定数组
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div><h4 id="对流中数据进行聚合计算"><a href="#对流中数据进行聚合计算" class="header-anchor">#</a> 对流中数据进行聚合计算</h4> <ul><li>当我们使用Stream流处理数据后，可以像数据库的聚合函数一样对某个字段进行操作。比如获取最大值，获取最小值，求总和，平均值，统计数量。</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamCollectTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">aggregation</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> personList <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"王五"</span><span class="token punctuation">,</span> <span class="token number">17</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小红"</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小明"</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">toList</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 获取最大值</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> optional <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">maxBy</span><span class="token punctuation">(</span><span class="token punctuation">(</span>o1<span class="token punctuation">,</span> o2<span class="token punctuation">)</span> <span class="token operator">-></span> o1<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> o2<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"最大值: "</span> <span class="token operator">+</span> optional<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 获取最小值</span>
|
||||
<span class="token class-name">Optional</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> optionalMin <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">minBy</span><span class="token punctuation">(</span><span class="token punctuation">(</span>o1<span class="token punctuation">,</span> o2<span class="token punctuation">)</span> <span class="token operator">-></span> o1<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> o2<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"最小值: "</span> <span class="token operator">+</span> optionalMin<span class="token punctuation">.</span><span class="token function">get</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 求总和</span>
|
||||
<span class="token class-name">Integer</span> totalAge <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">summingInt</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getAge</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"总和: "</span> <span class="token operator">+</span> totalAge<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 平均值</span>
|
||||
<span class="token class-name">Double</span> avg <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">averagingInt</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getAge</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"平均值: "</span> <span class="token operator">+</span> avg<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 统计数量</span>
|
||||
<span class="token class-name">Long</span> count <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">counting</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"总共: "</span> <span class="token operator">+</span> count<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 以上方法聚合</span>
|
||||
<span class="token class-name">IntSummaryStatistics</span> summaryStatistics <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">summarizingInt</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getAge</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"上面所有方法的聚合: "</span> <span class="token operator">+</span> summaryStatistics<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br></div></div><h4 id="对流中数据进行分组"><a href="#对流中数据进行分组" class="header-anchor">#</a> 对流中数据进行分组</h4> <ul><li>当我们使用Stream流处理数据后，可以根据某个属性将数据分组</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamCollectTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">group</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> personList <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"王五"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小红"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小明"</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">toList</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">// 通过年龄来进行分组</span>
|
||||
personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">groupingBy</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getAge</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 分组结果为键值对</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span>key<span class="token punctuation">,</span> value<span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>key <span class="token operator">+</span> <span class="token string">"::"</span> <span class="token operator">+</span> value<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 将年龄大于19的分为一组, 小于19分为一组</span>
|
||||
personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">groupingBy</span><span class="token punctuation">(</span>s <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">if</span><span class="token punctuation">(</span>s<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">return</span> <span class="token string">">=19"</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">return</span> <span class="token string">"<19"</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 分组结果为键值对, 键为groupingBy返回的数据</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span>k<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>k <span class="token operator">+</span> <span class="token string">"::"</span> <span class="token operator">+</span> v<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br></div></div><h4 id="对流中数据进行多级分组"><a href="#对流中数据进行多级分组" class="header-anchor">#</a> 对流中数据进行多级分组</h4> <ul><li>还可以对数据进行多级分组：</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamCollectTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">multiGroup</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> personList <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三丰"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"迪丽热巴"</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"古力娜扎"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"迪迦奥特曼"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"宇宙无敌法外狂徒张三"</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">toList</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 先根据年龄分组, 每组中再根据名字的长度分组</span>
|
||||
personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span>
|
||||
<span class="token comment">// 根据年龄分组</span>
|
||||
<span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">groupingBy</span><span class="token punctuation">(</span>p <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">if</span><span class="token punctuation">(</span>p<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">return</span> <span class="token string">"大于19"</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">return</span> <span class="token string">"小于等于19"</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">,</span>
|
||||
<span class="token comment">// 根据名字长度分组</span>
|
||||
<span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">groupingBy</span><span class="token punctuation">(</span>p <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">if</span><span class="token punctuation">(</span>p<span class="token punctuation">.</span><span class="token function">getName</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">length</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">4</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">return</span> <span class="token string">"较长的名字"</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">return</span> <span class="token string">"较短的名字"</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">)</span>
|
||||
<span class="token comment">// 结果的类型为: Map<String, Map<String, Person>></span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span>oneK<span class="token punctuation">,</span> oneV<span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"年龄"</span> <span class="token operator">+</span> oneK<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
oneV<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span>twoK<span class="token punctuation">,</span> twoV<span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"\t"</span> <span class="token operator">+</span> twoK <span class="token operator">+</span> <span class="token string">"::"</span> <span class="token operator">+</span> twoV<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">/*
|
||||
result -> {
|
||||
年龄小于等于19
|
||||
较长的名字::[Person{name='迪迦奥特曼', age=18}]
|
||||
较短的名字::[Person{name='张三丰', age=18}, Person{name='古力娜扎', age=18}]
|
||||
年龄大于19
|
||||
较长的名字::[Person{name='宇宙无敌法外狂徒张三', age=21}]
|
||||
较短的名字::[Person{name='迪丽热巴', age=22}]
|
||||
}
|
||||
*/</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br></div></div><h4 id="对流中数据进行分区"><a href="#对流中数据进行分区" class="header-anchor">#</a> 对流中数据进行分区</h4> <ul><li><code>Collectors.partitioningBy</code>会根据值是否为true，把集合分割为两个列表，一个true列表，一个false列表</li> <li><img src="/java8/%E6%B5%81%E6%95%B0%E6%8D%AE%E5%88%86%E5%8C%BA.png" alt=""></li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamCollectTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">partition</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> personList <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"王五"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小红"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小明"</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">toList</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 将结果分为, true和false两个分区</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">partitioningBy</span><span class="token punctuation">(</span>p <span class="token operator">-></span> p<span class="token punctuation">.</span><span class="token function">getAge</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">></span> <span class="token number">19</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token punctuation">(</span>k<span class="token punctuation">,</span> v<span class="token punctuation">)</span> <span class="token operator">-></span> <span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>k <span class="token operator">+</span> <span class="token string">"::"</span> <span class="token operator">+</span> v<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br></div></div><h4 id="对流中数据进行拼接"><a href="#对流中数据进行拼接" class="header-anchor">#</a> 对流中数据进行拼接</h4> <ul><li><code>Collectors.joining</code>会根据指定的连接符，将所有元素连接成一个字符串</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamCollectTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Person</span><span class="token punctuation">></span></span> personList <span class="token operator">=</span> <span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"张三"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"李四"</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"王五"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小红"</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
|
||||
<span class="token keyword">new</span> <span class="token class-name">Person</span><span class="token punctuation">(</span><span class="token string">"小明"</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">)</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">toList</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 根据一个字符拼接</span>
|
||||
<span class="token class-name">String</span> names <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getName</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">joining</span><span class="token punctuation">(</span><span class="token string">"-"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>names<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 根据三个字符拼接</span>
|
||||
names <span class="token operator">=</span> personList<span class="token punctuation">.</span><span class="token function">stream</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span><span class="token class-name">Person</span><span class="token operator">::</span><span class="token function">getName</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 参数说明: 分隔符, 前缀, 后缀</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">joining</span><span class="token punctuation">(</span><span class="token string">","</span><span class="token punctuation">,</span> <span class="token string">"{"</span><span class="token punctuation">,</span> <span class="token string">"}"</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span>names<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br></div></div></div></section> <footer class="page-edit"><!----> <!----></footer> <div class="page-nav"><p class="inner"><span class="prev"><a href="/blogs/java/java8/java8-1.html" class="prev">
|
||||
JDK8 特性（一）
|
||||
</a></span> <span class="next"><a href="/blogs/java/java8/java8-3.html">
|
||||
JDK8 特性（三）
|
||||
</a></span></p></div> <div class="comments-wrapper"><!----></div></main></div> <!----></div> <ul class="sub-sidebar sub-sidebar-wrapper" style="width:12rem;" data-v-b57cc07c data-v-7dd95ae2><li class="level-2" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-stream流" class="sidebar-link reco-side-_1-stream流" data-v-b57cc07c>1 Stream流</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-1-集合处理数据的弊端" class="sidebar-link reco-side-_1-1-集合处理数据的弊端" data-v-b57cc07c>1.1 集合处理数据的弊端</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-2-stream流式思想概述" class="sidebar-link reco-side-_1-2-stream流式思想概述" data-v-b57cc07c>1.2 Stream流式思想概述</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-3-获取stream流的两种方式" class="sidebar-link reco-side-_1-3-获取stream流的两种方式" data-v-b57cc07c>1.3 获取Stream流的两种方式</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-4-了解stream流的常用方法和注意事项" class="sidebar-link reco-side-_1-4-了解stream流的常用方法和注意事项" data-v-b57cc07c>1.4 了解Stream流的常用方法和注意事项</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-5-stream综合案例" class="sidebar-link reco-side-_1-5-stream综合案例" data-v-b57cc07c>1.5 Stream综合案例</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-2.html#_1-6-收集stream流中的结果" class="sidebar-link reco-side-_1-6-收集stream流中的结果" data-v-b57cc07c>1.6 收集Stream流中的结果</a></li></ul></div></div></div><div class="global-ui"><div class="back-to-ceiling" style="right:1rem;bottom:6rem;width:2.5rem;height:2.5rem;border-radius:.25rem;line-height:2.5rem;display:none;" data-v-c6073ba8 data-v-c6073ba8><svg t="1574745035067" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="5404" class="icon" data-v-c6073ba8><path d="M526.60727968 10.90185116a27.675 27.675 0 0 0-29.21455937 0c-131.36607665 82.28402758-218.69155461 228.01873535-218.69155402 394.07834331a462.20625001 462.20625001 0 0 0 5.36959153 69.94390903c1.00431239 6.55289093-0.34802892 13.13561351-3.76865779 18.80351572-32.63518765 54.11355614-51.75690182 118.55860487-51.7569018 187.94566865a371.06718723 371.06718723 0 0 0 11.50484808 91.98906777c6.53300375 25.50556257 41.68394495 28.14064038 52.69160883 4.22606766 17.37162448-37.73630017 42.14135425-72.50938081 72.80769204-103.21549295 2.18761121 3.04276886 4.15646224 6.24463696 6.40373557 9.22774369a1871.4375 1871.4375 0 0 0 140.04691725 5.34970492 1866.36093723 1866.36093723 0 0 0 140.04691723-5.34970492c2.24727335-2.98310674 4.21612437-6.18497483 6.3937923-9.2178004 30.66633723 30.70611158 55.4360664 65.4791928 72.80769147 103.21549355 11.00766384 23.91457269 46.15860503 21.27949489 52.69160879-4.22606768a371.15156223 371.15156223 0 0 0 11.514792-91.99901164c0-69.36717486-19.13165746-133.82216804-51.75690182-187.92578088-3.42062944-5.66790279-4.76302748-12.26056868-3.76865837-18.80351632a462.20625001 462.20625001 0 0 0 5.36959269-69.943909c-0.00994388-166.08943902-87.32547796-311.81420293-218.6915546-394.09823051zM605.93803103 357.87693858a93.93749974 93.93749974 0 1 1-187.89594924 6.1e-7 93.93749974 93.93749974 0 0 1 187.89594924-6.1e-7z" p-id="5405" data-v-c6073ba8></path><path d="M429.50777625 765.63860547C429.50777625 803.39355007 466.44236686 1000.39046097 512.00932183 1000.39046097c45.56695499 0 82.4922232-197.00623328 82.5015456-234.7518555 0-37.75494459-36.9345906-68.35043303-82.4922232-68.34111062-45.57627738-0.00932239-82.52019037 30.59548842-82.51086798 68.34111062z" p-id="5406" data-v-c6073ba8></path></svg></div></div></div>
|
||||
<script src="/assets/js/app.049e1b5b.js" defer></script><script src="/assets/js/3.ff0e945d.js" defer></script><script src="/assets/js/1.1ced4111.js" defer></script><script src="/assets/js/15.bd05cf61.js" defer></script>
|
||||
</body>
|
||||
</html>
|
||||
230
public/blogs/java/java8/java8-3.html
Normal file
230
public/blogs/java/java8/java8-3.html
Normal file
@@ -0,0 +1,230 @@
|
||||
<!DOCTYPE html>
|
||||
<html lang="zh-CN">
|
||||
<head>
|
||||
<meta charset="utf-8">
|
||||
<meta name="viewport" content="width=device-width,initial-scale=1">
|
||||
<title>JDK8 特性（三） | ZhuHJay Blog</title>
|
||||
<meta name="generator" content="VuePress 1.9.7">
|
||||
<link rel="icon" href="/favicon.ico">
|
||||
<meta name="description" content="my blog">
|
||||
<meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=no">
|
||||
|
||||
<link rel="preload" href="/assets/css/0.styles.93f9cd2e.css" as="style"><link rel="preload" href="/assets/js/app.049e1b5b.js" as="script"><link rel="preload" href="/assets/js/3.ff0e945d.js" as="script"><link rel="preload" href="/assets/js/1.1ced4111.js" as="script"><link rel="preload" href="/assets/js/16.346083d6.js" as="script"><link rel="prefetch" href="/assets/js/10.21e2f029.js"><link rel="prefetch" href="/assets/js/11.18770288.js"><link rel="prefetch" href="/assets/js/12.588a1dd8.js"><link rel="prefetch" href="/assets/js/13.e66c15d0.js"><link rel="prefetch" href="/assets/js/14.141a3334.js"><link rel="prefetch" href="/assets/js/15.bd05cf61.js"><link rel="prefetch" href="/assets/js/17.382f52f1.js"><link rel="prefetch" href="/assets/js/18.a55369bc.js"><link rel="prefetch" href="/assets/js/19.a2a264ee.js"><link rel="prefetch" href="/assets/js/20.c6871f96.js"><link rel="prefetch" href="/assets/js/21.2956f057.js"><link rel="prefetch" href="/assets/js/4.581595e5.js"><link rel="prefetch" href="/assets/js/5.55d6cfd7.js"><link rel="prefetch" href="/assets/js/6.9619dc5e.js"><link rel="prefetch" href="/assets/js/7.d2b7a379.js"><link rel="prefetch" href="/assets/js/8.9f502ca9.js"><link rel="prefetch" href="/assets/js/9.ec0bd674.js">
|
||||
<link rel="stylesheet" href="/assets/css/0.styles.93f9cd2e.css">
|
||||
</head>
|
||||
<body>
|
||||
<div id="app" data-server-rendered="true"><div class="theme-container" data-v-7dd95ae2><div data-v-7dd95ae2><div class="password-shadow password-wrapper-out" style="display:none;" data-v-59e6cb88 data-v-7dd95ae2 data-v-7dd95ae2><h3 class="title" data-v-59e6cb88>ZhuHJay Blog</h3> <p class="description" data-v-59e6cb88>my blog</p> <label id="box" class="inputBox" data-v-59e6cb88><input type="password" value="" data-v-59e6cb88> <span data-v-59e6cb88>Konck! Knock!</span> <button data-v-59e6cb88>OK</button></label> <div class="footer" data-v-59e6cb88><span data-v-59e6cb88><i class="iconfont reco-theme" data-v-59e6cb88></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-59e6cb88>vuePress-theme-reco</a></span> <span data-v-59e6cb88><i class="iconfont reco-copyright" data-v-59e6cb88></i> <a data-v-59e6cb88><span data-v-59e6cb88>ZhuHJay</span>
|
||||
|
||||
<span data-v-59e6cb88>2021 - </span>
|
||||
2025
|
||||
</a></span></div></div> <div class="hide" data-v-7dd95ae2><header class="navbar" data-v-7dd95ae2><div class="sidebar-button"><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" role="img" viewBox="0 0 448 512" class="icon"><path fill="currentColor" d="M436 124H12c-6.627 0-12-5.373-12-12V80c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12zm0 160H12c-6.627 0-12-5.373-12-12v-32c0-6.627 5.373-12 12-12h424c6.627 0 12 5.373 12 12v32c0 6.627-5.373 12-12 12z"></path></svg></div> <a href="/" class="home-link router-link-active"><img src="/logo.png" alt="ZhuHJay Blog" class="logo"> <span class="site-name">ZhuHJay Blog</span></a> <div class="links"><div class="color-picker"><a class="color-button"><i class="iconfont reco-color"></i></a> <div class="color-picker-menu" style="display:none;"><div class="mode-options"><h4 class="title">Choose mode</h4> <ul class="color-mode-options"><li class="dark">dark</li><li class="auto active">auto</li><li class="light">light</li></ul></div></div></div> <div class="search-box"><i class="iconfont reco-search"></i> <input aria-label="Search" autocomplete="off" spellcheck="false" value=""> <!----></div> <nav class="nav-links can-hide"><div class="nav-item"><a href="/" class="nav-link"><i class="iconfont reco-home"></i>
|
||||
首页
|
||||
</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title"><i class="iconfont reco-category"></i>
|
||||
分类
|
||||
</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/categories/Java/" class="nav-link"><i class="undefined"></i>
|
||||
Java
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/NoSQL/" class="nav-link"><i class="undefined"></i>
|
||||
NoSQL
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/JavaScript/" class="nav-link"><i class="undefined"></i>
|
||||
JavaScript
|
||||
</a></li></ul></div></div><div class="nav-item"><a href="/tag/" class="nav-link"><i class="iconfont reco-tag"></i>
|
||||
标签
|
||||
</a></div><div class="nav-item"><a href="https://gitee.com/ZhuHJay" target="_blank" rel="noopener noreferrer" class="nav-link external"><i class="iconfont reco-mayun"></i>
|
||||
码云
|
||||
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav></div></header> <div class="sidebar-mask" data-v-7dd95ae2></div> <aside class="sidebar" data-v-7dd95ae2><div class="personal-info-wrapper" data-v-1fad0c41 data-v-7dd95ae2><img src="/avatar.png" alt="author-avatar" class="personal-img" data-v-1fad0c41> <h3 class="name" data-v-1fad0c41>
|
||||
ZhuHJay
|
||||
</h3> <div class="num" data-v-1fad0c41><div data-v-1fad0c41><h3 data-v-1fad0c41>11</h3> <h6 data-v-1fad0c41>文章</h6></div> <div data-v-1fad0c41><h3 data-v-1fad0c41>5</h3> <h6 data-v-1fad0c41>标签</h6></div></div> <ul class="social-links" data-v-1fad0c41></ul> <hr data-v-1fad0c41></div> <nav class="nav-links"><div class="nav-item"><a href="/" class="nav-link"><i class="iconfont reco-home"></i>
|
||||
首页
|
||||
</a></div><div class="nav-item"><div class="dropdown-wrapper"><a class="dropdown-title"><span class="title"><i class="iconfont reco-category"></i>
|
||||
分类
|
||||
</span> <span class="arrow right"></span></a> <ul class="nav-dropdown" style="display:none;"><li class="dropdown-item"><!----> <a href="/categories/Java/" class="nav-link"><i class="undefined"></i>
|
||||
Java
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/NoSQL/" class="nav-link"><i class="undefined"></i>
|
||||
NoSQL
|
||||
</a></li><li class="dropdown-item"><!----> <a href="/categories/JavaScript/" class="nav-link"><i class="undefined"></i>
|
||||
JavaScript
|
||||
</a></li></ul></div></div><div class="nav-item"><a href="/tag/" class="nav-link"><i class="iconfont reco-tag"></i>
|
||||
标签
|
||||
</a></div><div class="nav-item"><a href="https://gitee.com/ZhuHJay" target="_blank" rel="noopener noreferrer" class="nav-link external"><i class="iconfont reco-mayun"></i>
|
||||
码云
|
||||
<span><svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" focusable="false" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg> <span class="sr-only">(opens new window)</span></span></a></div> <!----></nav> <ul class="sidebar-links"><li><a href="/blogs/java/java8/java8-1.html" class="sidebar-link">JDK8 特性（一）</a></li><li><a href="/blogs/java/java8/java8-2.html" class="sidebar-link">JDK8 特性（二）</a></li><li><a href="/blogs/java/java8/java8-3.html" aria-current="page" class="active sidebar-link">JDK8 特性（三）</a></li><li><a href="/blogs/java/java8/java8-4.html" class="sidebar-link">JDK8 特性（四）</a></li></ul> </aside> <div class="password-shadow password-wrapper-in" style="display:none;" data-v-59e6cb88 data-v-7dd95ae2><h3 class="title" data-v-59e6cb88>JDK8 特性（三）</h3> <!----> <label id="box" class="inputBox" data-v-59e6cb88><input type="password" value="" data-v-59e6cb88> <span data-v-59e6cb88>Konck! Knock!</span> <button data-v-59e6cb88>OK</button></label> <div class="footer" data-v-59e6cb88><span data-v-59e6cb88><i class="iconfont reco-theme" data-v-59e6cb88></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-59e6cb88>vuePress-theme-reco</a></span> <span data-v-59e6cb88><i class="iconfont reco-copyright" data-v-59e6cb88></i> <a data-v-59e6cb88><span data-v-59e6cb88>ZhuHJay</span>
|
||||
|
||||
<span data-v-59e6cb88>2021 - </span>
|
||||
2025
|
||||
</a></span></div></div> <div data-v-7dd95ae2><div data-v-7dd95ae2><main class="page"><section style="display:;"><div class="page-title"><h1 class="title">JDK8 特性（三）</h1> <div data-v-8a445198><i class="iconfont reco-account" data-v-8a445198><span data-v-8a445198>ZhuHJay</span></i> <i class="iconfont reco-date" data-v-8a445198><span data-v-8a445198>2022/5/25</span></i> <!----> <i class="tags iconfont reco-tag" data-v-8a445198><span class="tag-item" data-v-8a445198>JDK8</span></i></div></div> <div class="theme-reco-content content__default"><h2 id="_1-stream流-续"><a href="#_1-stream流-续" class="header-anchor">#</a> 1 Stream流-续</h2> <h3 id="_1-7-并行的stream流"><a href="#_1-7-并行的stream流" class="header-anchor">#</a> 1.7 并行的Stream流</h3> <ul><li><p>串行的Stream流</p> <ul><li>目前我们使用的Stream流是串行的，就是在一个线程上执行。</li></ul></li> <li><p>并行的Stream流</p> <ul><li>parallelStream其实就是一个并行执行的流。它通过默认的ForkJoinPool，可能提高多线程任务的速度。</li></ul></li></ul> <h4 id="获取并行stream流的两种方式"><a href="#获取并行stream流的两种方式" class="header-anchor">#</a> 获取并行Stream流的两种方式</h4> <ol><li>直接获取并行的流</li></ol> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamParallelTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token comment">// 直接获取并行的流 </span>
|
||||
<span class="token class-name">Stream</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> stream <span class="token operator">=</span> list<span class="token punctuation">.</span><span class="token function">parallelStream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br></div></div><ol start="2"><li>将串行流转成并行流</li></ol> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamParallelTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">serialToParallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">Stream</span><span class="token punctuation">.</span><span class="token function">of</span><span class="token punctuation">(</span><span class="token number">9</span><span class="token punctuation">,</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">34</span><span class="token punctuation">,</span> <span class="token number">5</span><span class="token punctuation">,</span> <span class="token number">3</span><span class="token punctuation">,</span> <span class="token number">21</span><span class="token punctuation">,</span> <span class="token number">56</span><span class="token punctuation">,</span> <span class="token number">9</span><span class="token punctuation">)</span>
|
||||
<span class="token comment">// 转成并行流</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">filter</span><span class="token punctuation">(</span>i <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token class-name">Thread</span><span class="token punctuation">.</span><span class="token function">currentThread</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">"::"</span> <span class="token operator">+</span> i<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">return</span> i <span class="token operator">></span> <span class="token number">50</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token operator">::</span><span class="token function">println</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br></div></div><h4 id="串行和并行效率的比较"><a href="#串行和并行效率的比较" class="header-anchor">#</a> 串行和并行效率的比较</h4> <ul><li>使用for循环，串行Stream流，并行Stream流来对10亿个数字求和。看消耗的时间。</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamParallelTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token keyword">int</span> <span class="token constant">TIMES</span> <span class="token operator">=</span> <span class="token number">1000000000</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">long</span> start<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token annotation punctuation">@Before</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">init</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
start <span class="token operator">=</span> <span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">useFor</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 消耗时间: 339ms</span>
|
||||
<span class="token keyword">int</span> sum <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">int</span> i <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span> i <span class="token operator"><</span> <span class="token constant">TIMES</span><span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
sum <span class="token operator">+=</span> i<span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">useSerialStream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 获取足够长度的串行流进行加和</span>
|
||||
<span class="token comment">// 消耗时间: 631ms</span>
|
||||
<span class="token class-name">LongStream</span><span class="token punctuation">.</span><span class="token function">rangeClosed</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token constant">TIMES</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token class-name">Long</span><span class="token operator">::</span><span class="token function">sum</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">useParallelStream</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token comment">// 获取足够长度的并行流进行加和</span>
|
||||
<span class="token comment">// 消耗时间: 317ms</span>
|
||||
<span class="token class-name">LongStream</span><span class="token punctuation">.</span><span class="token function">rangeClosed</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token constant">TIMES</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">reduce</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token class-name">Long</span><span class="token operator">::</span><span class="token function">sum</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@After</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">destroy</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"消耗时间: "</span> <span class="token operator">+</span>
|
||||
<span class="token punctuation">(</span><span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> start<span class="token punctuation">)</span> <span class="token operator">+</span>
|
||||
<span class="token string">"ms"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br></div></div><ul><li>我们可以看到parallelStream的效率是最高的。</li> <li>Stream并行处理的过程会分而治之，也就是将一个大任务切分成多个小任务，这表示每个任务都是一个操作。</li></ul> <h4 id="parallelstream线程安全问题"><a href="#parallelstream线程安全问题" class="header-anchor">#</a> ParallelStream线程安全问题</h4> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">StreamParallelTest</span> <span class="token punctuation">{</span>
|
||||
<span class="token annotation punctuation">@Test</span>
|
||||
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">parallelStreamNotice</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> list <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ArrayList</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 并行线程不安全</span>
|
||||
<span class="token comment">// list.size() = 947</span>
|
||||
<span class="token class-name">IntStream</span><span class="token punctuation">.</span><span class="token function">range</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>i <span class="token operator">-></span> list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"list.size() = "</span> <span class="token operator">+</span> list<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 解决线程安全问题方案一: 使用同步代码块</span>
|
||||
<span class="token class-name">Object</span> lock <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Object</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">IntStream</span><span class="token punctuation">.</span><span class="token function">range</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>i <span class="token operator">-></span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">synchronized</span> <span class="token punctuation">(</span>lock<span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
list<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"list.size() = "</span> <span class="token operator">+</span> list<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 解决线程安全问题方案二: 使用线程安全的集合</span>
|
||||
<span class="token comment">// 使用 Vector<Integer> 集合</span>
|
||||
<span class="token class-name">Vector</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> v <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Vector</span><span class="token generics"><span class="token punctuation"><</span><span class="token punctuation">></span></span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">IntStream</span><span class="token punctuation">.</span><span class="token function">range</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>i <span class="token operator">-></span> v<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"v.size() = "</span> <span class="token operator">+</span> v<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 解决线程安全问题方案二: 使用线程安全的集合</span>
|
||||
<span class="token comment">// 使用集合工具类提供的线程安全的集合</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> synchronizedList <span class="token operator">=</span> <span class="token class-name">Collections</span><span class="token punctuation">.</span><span class="token function">synchronizedList</span><span class="token punctuation">(</span>list<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">IntStream</span><span class="token punctuation">.</span><span class="token function">range</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">forEach</span><span class="token punctuation">(</span>i <span class="token operator">-></span> synchronizedList<span class="token punctuation">.</span><span class="token function">add</span><span class="token punctuation">(</span>i<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"synchronizedList.size() = "</span> <span class="token operator">+</span> synchronizedList<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 解决线程安全问题方案三: 调用Stream流的collect/toArray</span>
|
||||
<span class="token comment">// 使用Stream流的collect</span>
|
||||
<span class="token class-name">List</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Integer</span><span class="token punctuation">></span></span> collect <span class="token operator">=</span> <span class="token class-name">IntStream</span><span class="token punctuation">.</span><span class="token function">range</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">boxed</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">collect</span><span class="token punctuation">(</span><span class="token class-name">Collectors</span><span class="token punctuation">.</span><span class="token function">toList</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"collect.size() = "</span> <span class="token operator">+</span> collect<span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token comment">// 解决线程安全问题方案三: 调用Stream流的collect/toArray</span>
|
||||
<span class="token comment">// 使用Stream流的toArray</span>
|
||||
<span class="token class-name">Integer</span><span class="token punctuation">[</span><span class="token punctuation">]</span> integers <span class="token operator">=</span> <span class="token class-name">IntStream</span><span class="token punctuation">.</span><span class="token function">range</span><span class="token punctuation">(</span><span class="token number">0</span><span class="token punctuation">,</span> <span class="token number">1000</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">parallel</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">boxed</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
|
||||
<span class="token punctuation">.</span><span class="token function">toArray</span><span class="token punctuation">(</span><span class="token class-name">Integer</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token operator">::</span><span class="token keyword">new</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"integers.length = "</span> <span class="token operator">+</span> integers<span class="token punctuation">.</span>length<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br><span class="line-number">50</span><br><span class="line-number">51</span><br><span class="line-number">52</span><br><span class="line-number">53</span><br><span class="line-number">54</span><br><span class="line-number">55</span><br><span class="line-number">56</span><br></div></div><h3 id="_1-8-fork-join框架介绍"><a href="#_1-8-fork-join框架介绍" class="header-anchor">#</a> 1.8 Fork/Join框架介绍</h3> <ul><li>parallelStream使用的是Fork/Join框架。Fork/Join框架自JDK 7引入。Fork/Join框架可以将一个大任务拆分为很多小 任务来异步执行。 Fork/Join框架主要包含三个模块：
|
||||
<ol><li>线程池：ForkJoinPool</li> <li>任务对象：ForkJoinTask</li> <li>执行任务的线程：ForkJoinWorkerThread</li></ol></li></ul> <p><img src="/java8/ForkJoin%E4%B8%80%E8%A7%88.png" alt=""></p> <h4 id="fork-join原理-分治法"><a href="#fork-join原理-分治法" class="header-anchor">#</a> Fork/Join原理-分治法</h4> <ul><li>ForkJoinPool主要用来使用分治法(Divide-and-Conquer Algorithm)来解决问题。典型的应用比如快速排序算法，ForkJoinPool需要使用相对少的线程来处理大量的任务。比如要对1000万个数据进行排序，那么会将这个任务分割成 两个500万的排序任务和一个针对这两组500万数据的合并任务。以此类推，对于500万的数据也会做出同样的分割处理，到最后会设置一个阈值来规定当数据规模到多少时，停止这样的分割处理。比如，当元素的数量小于10时，会停止分割，转而使用插入排序对它们进行排序。那么到最后，所有的任务加起来会有大概2000000+个。问题的关键在于，对于一个任务而言，只有当它所有的子任务完成之后，它才能够被执行。</li></ul> <p><img src="/java8/ForkJoin-%E5%88%86%E6%B2%BB%E6%B3%95.png" alt=""></p> <h4 id="fork-join原理-工作窃取算法"><a href="#fork-join原理-工作窃取算法" class="header-anchor">#</a> Fork/Join原理-工作窃取算法</h4> <ul><li>Fork/Join最核心的地方就是利用了现代硬件设备多核，在一个操作时候会有空闲的cpu，那么如何利用好这个空闲的cpu就成了提高性能的关键，而这里我们要提到的工作窃取（work-stealing）算法就是整个Fork/Join框架的核心理念 Fork/Join工作窃取（work-stealing）算法是指某个线程从其他队列里窃取任务来执行。</li></ul> <p><img src="/java8/ForkJoin-%E5%B7%A5%E4%BD%9C%E7%AA%83%E5%8F%96%E7%AE%97%E6%B3%95.png" alt=""></p> <ul><li><p>那么为什么需要使用工作窃取算法呢？假如我们需要做一个比较大的任务，我们可以把这个任务分割为若干互不依赖的子任务，为了减少线程间的竞争，于是把这些子任务分别放到不同的队列里，并为每个队列创建一个单独的线程来执行队列里的任务，线程和队列一一对应，比如A线程负责处理A队列里的任务。但是有的线程会先把自己队列里的 任务干完，而其他线程对应的队列里还有任务等待处理。干完活的线程与其等着，不如去帮其他线程干活，于是它就去其他线程的队列里窃取一个任务来执行。而在这时它们会访问同一个队列，所以为了减少窃取任务线程和被窃取任 务线程之间的竞争，通常会使用双端队列，被窃取任务线程永远从双端队列的头部拿任务执行，而窃取任务的线程永 远从双端队列的尾部拿任务执行。</p></li> <li><p>工作窃取算法的优点是充分利用线程进行并行计算，并减少了线程间的竞争，其缺点是在某些情况下还是存在竞争，比如双端队列里只有一个任务时。并且消耗了更多的系统资源，比如创建多个线程和多个双端队列。</p></li> <li><p>上文中已经提到了在Java 8引入了自动并行化的概念。它能够让一部分Java代码自动地以并行的方式执行，也就是我们使用了ForkJoinPool的ParallelStream。</p></li> <li><p>对于ForkJoinPool通用线程池的线程数量，通常使用默认值就可以了，即运行时计算机的处理器数量。可以通过设置系统属性：<code>java.util.concurrent.ForkJoinPool.common.parallelism=N</code>（N为线程数量），来调整ForkJoinPool的线程数量，可以尝试调整成不同的参数来观察每次的输出结果。</p></li></ul> <h4 id="fork-join案例"><a href="#fork-join案例" class="header-anchor">#</a> Fork/Join案例</h4> <ul><li>需求：使用Fork/Join计算1-10000的和，当一个任务的计算数量大于3000时拆分任务，数量小于3000时计算。</li></ul> <p><img src="/java8/ForkJoin%E6%A1%88%E4%BE%8B.png" alt=""></p> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">ForkJoinDemo</span> <span class="token punctuation">{</span>
|
||||
|
||||
<span class="token keyword">public</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">main</span><span class="token punctuation">(</span><span class="token class-name">String</span><span class="token punctuation">[</span><span class="token punctuation">]</span> args<span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">long</span> start <span class="token operator">=</span> <span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">ForkJoinPool</span> pool <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">ForkJoinPool</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">SumRecursiveTask</span> task <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">SumRecursiveTask</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">10000L</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">Long</span> result <span class="token operator">=</span> pool<span class="token punctuation">.</span><span class="token function">invoke</span><span class="token punctuation">(</span>task<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"result = "</span> <span class="token operator">+</span> result<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">long</span> end <span class="token operator">=</span> <span class="token class-name">System</span><span class="token punctuation">.</span><span class="token function">currentTimeMillis</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token class-name">System</span><span class="token punctuation">.</span>out<span class="token punctuation">.</span><span class="token function">println</span><span class="token punctuation">(</span><span class="token string">"消耗的时间为: "</span> <span class="token operator">+</span> <span class="token punctuation">(</span>end <span class="token operator">-</span> start<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token keyword">class</span> <span class="token class-name">SumRecursiveTask</span> <span class="token keyword">extends</span> <span class="token class-name">RecursiveTask</span><span class="token generics"><span class="token punctuation"><</span><span class="token class-name">Long</span><span class="token punctuation">></span></span> <span class="token punctuation">{</span>
|
||||
|
||||
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">final</span> <span class="token keyword">long</span> <span class="token constant">THRESHOLD</span> <span class="token operator">=</span> <span class="token number">3000L</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">private</span> <span class="token keyword">final</span> <span class="token keyword">long</span> start<span class="token punctuation">;</span>
|
||||
<span class="token keyword">private</span> <span class="token keyword">final</span> <span class="token keyword">long</span> end<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token keyword">public</span> <span class="token class-name">SumRecursiveTask</span><span class="token punctuation">(</span><span class="token keyword">long</span> start<span class="token punctuation">,</span> <span class="token keyword">long</span> end<span class="token punctuation">)</span><span class="token punctuation">{</span>
|
||||
<span class="token keyword">this</span><span class="token punctuation">.</span>start <span class="token operator">=</span> start<span class="token punctuation">;</span>
|
||||
<span class="token keyword">this</span><span class="token punctuation">.</span>end <span class="token operator">=</span> end<span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
|
||||
<span class="token annotation punctuation">@Override</span>
|
||||
<span class="token keyword">protected</span> <span class="token class-name">Long</span> <span class="token function">compute</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token keyword">long</span> length <span class="token operator">=</span> end <span class="token operator">-</span> start<span class="token punctuation">;</span>
|
||||
|
||||
<span class="token keyword">if</span> <span class="token punctuation">(</span>length <span class="token operator"><=</span> <span class="token constant">THRESHOLD</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
<span class="token comment">// 任务不用再拆分了.可以计算了</span>
|
||||
<span class="token keyword">long</span> sum <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">for</span> <span class="token punctuation">(</span><span class="token keyword">long</span> i <span class="token operator">=</span> start<span class="token punctuation">;</span> i <span class="token operator"><=</span> end<span class="token punctuation">;</span> i<span class="token operator">++</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
|
||||
sum <span class="token operator">+=</span> i<span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token keyword">return</span> sum<span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span> <span class="token keyword">else</span> <span class="token punctuation">{</span>
|
||||
<span class="token comment">// 数量大于预定的数量,任务还需要再拆分</span>
|
||||
<span class="token keyword">long</span> middle <span class="token operator">=</span> <span class="token punctuation">(</span>start <span class="token operator">+</span> end<span class="token punctuation">)</span> <span class="token operator">/</span> <span class="token number">2</span><span class="token punctuation">;</span>
|
||||
|
||||
<span class="token class-name">SumRecursiveTask</span> left <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">SumRecursiveTask</span><span class="token punctuation">(</span>start<span class="token punctuation">,</span> middle<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
left<span class="token punctuation">.</span><span class="token function">fork</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token class-name">SumRecursiveTask</span> right <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">SumRecursiveTask</span><span class="token punctuation">(</span>middle <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> end<span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
right<span class="token punctuation">.</span><span class="token function">fork</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token keyword">return</span> left<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">+</span> right<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
<span class="token punctuation">}</span>
|
||||
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br><span class="line-number">27</span><br><span class="line-number">28</span><br><span class="line-number">29</span><br><span class="line-number">30</span><br><span class="line-number">31</span><br><span class="line-number">32</span><br><span class="line-number">33</span><br><span class="line-number">34</span><br><span class="line-number">35</span><br><span class="line-number">36</span><br><span class="line-number">37</span><br><span class="line-number">38</span><br><span class="line-number">39</span><br><span class="line-number">40</span><br><span class="line-number">41</span><br><span class="line-number">42</span><br><span class="line-number">43</span><br><span class="line-number">44</span><br><span class="line-number">45</span><br><span class="line-number">46</span><br><span class="line-number">47</span><br><span class="line-number">48</span><br><span class="line-number">49</span><br></div></div><h3 id="_1-9-小结"><a href="#_1-9-小结" class="header-anchor">#</a> 1.9 小结</h3> <ol><li>parallelStream是线程不安全的</li> <li>parallelStream适用的场景是CPU密集型的，只是做到别浪费CPU，假如本身电脑CPU的负载很大，那还到处用并行流，那并不能起到作用</li> <li>I/O密集型磁盘I/O、网络I/O都属于I/O操作，这部分操作是较少消耗CPU资源，一般并行流中不适用于I/O密集型的操作，就比如使用并流行进行大批量的消息推送，涉及到了大量I/O，使用并行流反而慢了很多</li> <li>在使用并行流的时候是无法保证元素的顺序的，也就是即使你用了同步集合也只能保证元素都正确但无法保证其中的顺序</li></ol></div></section> <footer class="page-edit"><!----> <!----></footer> <div class="page-nav"><p class="inner"><span class="prev"><a href="/blogs/java/java8/java8-2.html" class="prev">
|
||||
JDK8 特性（二）
|
||||
</a></span> <span class="next"><a href="/blogs/java/java8/java8-4.html">
|
||||
JDK8 特性（四）
|
||||
</a></span></p></div> <div class="comments-wrapper"><!----></div></main></div> <!----></div> <ul class="sub-sidebar sub-sidebar-wrapper" style="width:12rem;" data-v-b57cc07c data-v-7dd95ae2><li class="level-2" data-v-b57cc07c><a href="/blogs/java/java8/java8-3.html#_1-stream流-续" class="sidebar-link reco-side-_1-stream流-续" data-v-b57cc07c>1 Stream流-续</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-3.html#_1-7-并行的stream流" class="sidebar-link reco-side-_1-7-并行的stream流" data-v-b57cc07c>1.7 并行的Stream流</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-3.html#_1-8-fork-join框架介绍" class="sidebar-link reco-side-_1-8-fork-join框架介绍" data-v-b57cc07c>1.8 Fork/Join框架介绍</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-3.html#_1-9-小结" class="sidebar-link reco-side-_1-9-小结" data-v-b57cc07c>1.9 小结</a></li></ul></div></div></div><div class="global-ui"><div class="back-to-ceiling" style="right:1rem;bottom:6rem;width:2.5rem;height:2.5rem;border-radius:.25rem;line-height:2.5rem;display:none;" data-v-c6073ba8 data-v-c6073ba8><svg t="1574745035067" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="5404" class="icon" data-v-c6073ba8><path d="M526.60727968 10.90185116a27.675 27.675 0 0 0-29.21455937 0c-131.36607665 82.28402758-218.69155461 228.01873535-218.69155402 394.07834331a462.20625001 462.20625001 0 0 0 5.36959153 69.94390903c1.00431239 6.55289093-0.34802892 13.13561351-3.76865779 18.80351572-32.63518765 54.11355614-51.75690182 118.55860487-51.7569018 187.94566865a371.06718723 371.06718723 0 0 0 11.50484808 91.98906777c6.53300375 25.50556257 41.68394495 28.14064038 52.69160883 4.22606766 17.37162448-37.73630017 42.14135425-72.50938081 72.80769204-103.21549295 2.18761121 3.04276886 4.15646224 6.24463696 6.40373557 9.22774369a1871.4375 1871.4375 0 0 0 140.04691725 5.34970492 1866.36093723 1866.36093723 0 0 0 140.04691723-5.34970492c2.24727335-2.98310674 4.21612437-6.18497483 6.3937923-9.2178004 30.66633723 30.70611158 55.4360664 65.4791928 72.80769147 103.21549355 11.00766384 23.91457269 46.15860503 21.27949489 52.69160879-4.22606768a371.15156223 371.15156223 0 0 0 11.514792-91.99901164c0-69.36717486-19.13165746-133.82216804-51.75690182-187.92578088-3.42062944-5.66790279-4.76302748-12.26056868-3.76865837-18.80351632a462.20625001 462.20625001 0 0 0 5.36959269-69.943909c-0.00994388-166.08943902-87.32547796-311.81420293-218.6915546-394.09823051zM605.93803103 357.87693858a93.93749974 93.93749974 0 1 1-187.89594924 6.1e-7 93.93749974 93.93749974 0 0 1 187.89594924-6.1e-7z" p-id="5405" data-v-c6073ba8></path><path d="M429.50777625 765.63860547C429.50777625 803.39355007 466.44236686 1000.39046097 512.00932183 1000.39046097c45.56695499 0 82.4922232-197.00623328 82.5015456-234.7518555 0-37.75494459-36.9345906-68.35043303-82.4922232-68.34111062-45.57627738-0.00932239-82.52019037 30.59548842-82.51086798 68.34111062z" p-id="5406" data-v-c6073ba8></path></svg></div></div></div>
|
||||
<script src="/assets/js/app.049e1b5b.js" defer></script><script src="/assets/js/3.ff0e945d.js" defer></script><script src="/assets/js/1.1ced4111.js" defer></script><script src="/assets/js/16.346083d6.js" defer></script>
|
||||
</body>
|
||||
</html>
|
||||
342
public/blogs/java/java8/java8-4.html
Normal file
342
public/blogs/java/java8/java8-4.html
Normal file
File diff suppressed because one or more lines are too long
599
public/blogs/java/jvm/JVM-内存结构.html
Normal file
599
public/blogs/java/jvm/JVM-内存结构.html
Normal file
File diff suppressed because one or more lines are too long
308
public/blogs/java/jvm/JVM-垃圾回收.html
Normal file
308
public/blogs/java/jvm/JVM-垃圾回收.html
Normal file
File diff suppressed because one or more lines are too long
1322
public/blogs/java/jvm/JVM-字节码技术.html
Normal file
1322
public/blogs/java/jvm/JVM-字节码技术.html
Normal file
File diff suppressed because one or more lines are too long
649
public/blogs/java/jvm/JVM-类加载.html
Normal file
649
public/blogs/java/jvm/JVM-类加载.html
Normal file
File diff suppressed because one or more lines are too long
Reference in New Issue
Block a user