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zhuhjay 22e48d9558 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
2025-11-01 13:36:00 +08:00

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<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" aria-current="page" class="active 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" 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（一）</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>
  
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</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（一）</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>2022/5/23</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-lambda表达式"><a href="#_1-lambda表达式" class="header-anchor">#</a> 1 Lambda表达式</h2> <h3 id="_1-1-lambda标准格式"><a href="#_1-1-lambda标准格式" class="header-anchor">#</a> 1.1 Lambda标准格式</h3> <ul><li>Lambda省去面向对象的条条框框, Lambda的标准格式格式由3个部分组成</li> <li>格式说明:
<ul><li><code>(...args)</code>: 参数列表</li> <li><code>-&gt;</code>: 分隔或连接参数与方法体的标识符</li> <li><code>{...;}</code>: 方法体, 主要的代码逻辑</li></ul></li> <li>eg:</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">class</span> <span class="token class-name">Demo</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">new</span> <span class="token class-name">Thread</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-&gt;</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">&quot;线程启动&quot;</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">start</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></div></div><h3 id="_1-2-lambda初体验"><a href="#_1-2-lambda初体验" class="header-anchor">#</a> 1.2 Lambda初体验</h3> <h4 id="无参无返回值"><a href="#无参无返回值" class="header-anchor">#</a> 无参无返回值</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">Demo1</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 function">fishDo</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-&gt;</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">&quot;小鱼在欢乐的游着...&quot;</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">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">fishDo</span><span class="token punctuation">(</span><span class="token class-name">Fish</span> fish<span class="token punctuation">)</span><span class="token punctuation">{</span>
fish<span class="token punctuation">.</span><span class="token function">swim</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">/**
* 定义一个接口, 并且该接口只有一个需要实现的方法
**/</span>
<span class="token keyword">interface</span> <span class="token class-name">Fish</span><span class="token punctuation">{</span>
<span class="token keyword">void</span> <span class="token function">swim</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></div></div><h4 id="有参有返回值"><a href="#有参有返回值" class="header-anchor">#</a> 有参有返回值</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">Demo1</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 function">catEat</span><span class="token punctuation">(</span>foodName <span class="token operator">-&gt;</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">&quot;小猫在吃&quot;</span> <span class="token operator">+</span> foodName<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token number">3</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 keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">catEat</span><span class="token punctuation">(</span><span class="token class-name">Cat</span> cat<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">&quot;小猫吃了&quot;</span> <span class="token operator">+</span> cat<span class="token punctuation">.</span><span class="token function">eat</span><span class="token punctuation">(</span><span class="token string">&quot;🐟&quot;</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">&quot;分钟&quot;</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">/**
* 定义一个接口, 并且该接口只有一个需要实现的方法
**/</span>
<span class="token keyword">interface</span> <span class="token class-name">Cat</span><span class="token punctuation">{</span>
<span class="token keyword">int</span> <span class="token function">eat</span><span class="token punctuation">(</span><span class="token class-name">String</span> foodName<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="小结"><a href="#小结" class="header-anchor">#</a> 小结</h4> <p>以后我们调用方法时,看到参数是接口就可以考虑使用Lambda表达式,Lambda表达式相当于是对接口中抽象方法的重写</p> <h3 id="_1-3-lambda实现原理"><a href="#_1-3-lambda实现原理" class="header-anchor">#</a> 1.3 Lambda实现原理</h3> <p>现有以下类</p> <ul><li><p>接口类</p> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">interface</span> <span class="token class-name">Swimable</span> <span class="token punctuation">{</span>
<span class="token keyword">void</span> <span class="token function">swimming</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></div></div></li> <li><p>main入口</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">SwimImplDemo</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 function">goSwimming</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Swimable</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token annotation punctuation">@Override</span>
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">swimming</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">&quot;去匿名内部类游泳了&quot;</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 keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">goSwimming</span><span class="token punctuation">(</span><span class="token class-name">Swimable</span> swim<span class="token punctuation">)</span><span class="token punctuation">{</span>
swim<span class="token punctuation">.</span><span class="token function">swimming</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></li> <li><p>将以上的main方法进行执行后, 会编译生成以下字节码文件</p> <ul><li><img src="/java8/%E5%8C%BF%E5%90%8D%E5%86%85%E9%83%A8%E7%B1%BB%E7%94%9F%E6%88%90%E7%9A%84%E5%AD%97%E8%8A%82%E7%A0%81.png" alt=""></li></ul></li> <li><p>将内部类的字节码文件通过 [XJad] 进行反编译</p> <ul><li>匿名内部类在编译后会形成一个新的类.$</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token comment">// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.</span>
<span class="token comment">// Jad home page: http://kpdus.tripod.com/jad.html</span>
<span class="token comment">// Decompiler options: packimports(3) fieldsfirst ansi space</span>
<span class="token comment">// Source File Name: SwimImplDemo.java</span>
<span class="token keyword">package</span> <span class="token namespace">com<span class="token punctuation">.</span>zhuhjay<span class="token punctuation">.</span>lambda</span><span class="token punctuation">;</span>
<span class="token keyword">import</span> <span class="token import"><span class="token namespace">java<span class="token punctuation">.</span>io<span class="token punctuation">.</span></span><span class="token class-name">PrintStream</span></span><span class="token punctuation">;</span>
<span class="token comment">// Referenced classes of package com.zhuhjay.lambda:</span>
<span class="token comment">// Swimable, SwimImplDemo</span>
<span class="token keyword">static</span> <span class="token keyword">class</span> <span class="token class-name">SwimImplDemo</span>$<span class="token number">1</span> <span class="token keyword">implements</span> <span class="token class-name">Swimable</span><span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">swimming</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">&quot;去匿名内部类游泳了&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token class-name">SwimImplDemo</span>$<span class="token function">1</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></div></div></li> <li><p>main入口改为使用Lambda表达式</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">SwimImplDemo</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 function">goSwimming</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-&gt;</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">&quot;去Lambda游泳了&quot;</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 keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">goSwimming</span><span class="token punctuation">(</span><span class="token class-name">Swimable</span> swim<span class="token punctuation">)</span><span class="token punctuation">{</span>
swim<span class="token punctuation">.</span><span class="token function">swimming</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></div></div></li> <li><p>将以上的main方法进行执行后, 不会生成多余的字节码文件</p> <ul><li>使用 [XJad] 反编译工具会失败</li> <li>使用JDK工具来对Lambda表达式的字节码进行反汇编</li></ul> <div class="language-text line-numbers-mode"><pre class="language-text"><code>javap -c -p 文件名.class
-c：表示对代码进行反汇编 -p：显示所有类和成员
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br></div></div></li> <li><p>对Lambda表达式的字节码文件进行反汇编</p> <div class="language-S line-numbers-mode"><pre class="language-text"><code>public class com.zhuhjay.lambda.SwimImplDemo {
public com.zhuhjay.lambda.SwimImplDemo();
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object.&quot;&lt;init&gt;&quot;:()V
4: return
public static void main(java.lang.String[]);
Code:
0: invokedynamic #2, 0 // InvokeDynamic #0:swimming:()Lcom/zhuhjay/lambda/Swimable;
5: invokestatic #3 // Method goSwimming:(Lcom/zhuhjay/lambda/Swimable;)V
8: return
private static void goSwimming(com.zhuhjay.lambda.Swimable);
Code:
0: aload_0
1: invokeinterface #4, 1 // InterfaceMethod com/zhuhjay/lambda/Swimable.swimming:()V
6: return
private static void lambda$main$0();
Code:
0: getstatic #5 // Field java/lang/System.out:Ljava/io/PrintStream;
3: ldc #6 // String 去Lambda游泳了
5: invokevirtual #7 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
8: return
}
</code></pre> <div class="line-numbers-wrapper"><span class="line-number">1</span><br><span class="line-number">2</span><br><span class="line-number">3</span><br><span class="line-number">4</span><br><span class="line-number">5</span><br><span class="line-number">6</span><br><span class="line-number">7</span><br><span class="line-number">8</span><br><span class="line-number">9</span><br><span class="line-number">10</span><br><span class="line-number">11</span><br><span class="line-number">12</span><br><span class="line-number">13</span><br><span class="line-number">14</span><br><span class="line-number">15</span><br><span class="line-number">16</span><br><span class="line-number">17</span><br><span class="line-number">18</span><br><span class="line-number">19</span><br><span class="line-number">20</span><br><span class="line-number">21</span><br><span class="line-number">22</span><br><span class="line-number">23</span><br><span class="line-number">24</span><br><span class="line-number">25</span><br><span class="line-number">26</span><br></div></div><ul><li><p>通过与源代码的比较后, 发现多了静态方法<code>lambda$main$0</code></p></li> <li><p>得出: Lambda表达式会在类中新生成一个私有的静态方法, 命名为<code>lambda$方法名$序列</code></p></li> <li><p>通过断点调试Lambda也可以从调用栈中发现该静态方法的生成(当然不会显式的在源码中出现)</p></li> <li><p>验证在Lambda表达式运行中会生成一个内部类</p> <ul><li><p>命令格式: <code>java -Djdk.internal.lambda.dumpProxyClasses 要运行的包名.类名</code></p></li> <li><p>执行(需要退出包运行该命令): <code>java -Djdk.internal.lambda.dumpProxyClasses com.zhuhjay.lambda.SwimImplDemo</code></p> <ul><li><img src="/java8/%E8%8E%B7%E5%BE%97%E8%BF%90%E8%A1%8C%E6%97%B6Lambda%E5%86%85%E9%83%A8%E7%B1%BB.png" alt=""></li> <li>查看反编译结果</li></ul> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token keyword">final</span> <span class="token keyword">class</span> <span class="token class-name">SwimImplDemo</span>$$<span class="token class-name">Lambda</span>$<span class="token number">1</span>
<span class="token keyword">implements</span> <span class="token class-name">Swimable</span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">swimming</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token class-name">SwimImplDemo</span><span class="token punctuation">.</span>lambda$main$<span class="token function">0</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">private</span> <span class="token class-name">SwimImplDemo</span>$$<span class="token class-name">Lambda</span>$<span class="token function">1</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></div></div></li></ul></li></ul></li> <li><p>对以上结论来推断Lambda生成的字节码文件</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">SwimImplDemo</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 comment">// 也是相当于Lambda生成了一个匿名内部类, 来调用Lambda生成的静态方法</span>
<span class="token function">goSwimming</span><span class="token punctuation">(</span><span class="token keyword">new</span> <span class="token class-name">Swimable</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">void</span> <span class="token function">swimming</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token class-name">SwimImplDemo</span><span class="token punctuation">.</span>lambda$main$<span class="token function">0</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment">/** Lambda生成的私有静态方法 **/</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> lambda$main$<span class="token function">0</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">&quot;去Lambda游泳了&quot;</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">goSwimming</span><span class="token punctuation">(</span><span class="token class-name">Swimable</span> swim<span class="token punctuation">)</span><span class="token punctuation">{</span>
swim<span class="token punctuation">.</span><span class="token function">swimming</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><ul><li>小结
<ul><li>匿名内部类在编译的时候会一个class文件</li> <li>Lambda在程序运行的时候形成一个类
<ol><li>在类中新增一个方法,这个方法的方法体就是Lambda表达式中的代码</li> <li>还会形成一个匿名内部类, 实现接口, 重写抽象方法</li> <li>在接口的重写方法中会调用新生成的方法.</li></ol></li></ul></li></ul> <h3 id="_1-4-lambda省略格式"><a href="#_1-4-lambda省略格式" class="header-anchor">#</a> 1.4 Lambda省略格式</h3> <p>在Lambda标准格式的基础上，使用省略写法的规则为：</p> <ol><li>小括号内参数的类型可以省略</li> <li>如果小括号内有且仅有一个参数，则小括号可以省略</li> <li>如果大括号内有且仅有一个语句，可以同时省略大括号、return关键字及语句分号</li></ol> <h3 id="_1-5-lambda前提条件"><a href="#_1-5-lambda前提条件" class="header-anchor">#</a> 1.5 Lambda前提条件</h3> <p>Lambda的语法非常简洁，但是Lambda表达式不是随便使用的，使用时有几个条件要特别注意：</p> <ol><li>方法的参数或局部变量类型必须为接口才能使用Lambda</li> <li>接口中有且仅有一个抽象方法(@FunctionalInterface用来检测接口是否为函数式接口)</li></ol> <h3 id="_1-6-lambda和匿名内部类对比"><a href="#_1-6-lambda和匿名内部类对比" class="header-anchor">#</a> 1.6 Lambda和匿名内部类对比</h3> <ol><li>所需的类型不一样</li></ol> <ul><li>匿名内部类,需要的类型可以是类,抽象类,接口</li> <li>Lambda表达式,需要的类型必须是接口</li></ul> <ol start="2"><li>抽象方法的数量不一样</li></ol> <ul><li>匿名内部类所需的接口中抽象方法的数量随意</li> <li>Lambda表达式所需的接口只能有一个抽象方法</li></ul> <ol start="3"><li>实现原理不同</li></ol> <ul><li>匿名内部类是在编译后会形成class</li> <li>Lambda表达式是在程序运行的时候动态生成class</li></ul> <h2 id="_2-jdk8接口增强"><a href="#_2-jdk8接口增强" class="header-anchor">#</a> 2 JDK8接口增强</h2> <h3 id="_2-1-增强介绍"><a href="#_2-1-增强介绍" class="header-anchor">#</a> 2.1 增强介绍</h3> <ul><li><p>JDK8以前的接口:</p> <div class="language-text line-numbers-mode"><pre class="language-text"><code>interface 接口名 {
静态常量;
抽象方法;
}
</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></div></div></li> <li><p>JDK8的接口:</p> <div class="language-text line-numbers-mode"><pre class="language-text"><code>interface 接口名 {
静态常量;
抽象方法;
默认方法;
静态方法;
}
</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></div></div></li></ul> <h3 id="_2-2-接口默认方法和静态方法的区别"><a href="#_2-2-接口默认方法和静态方法的区别" class="header-anchor">#</a> 2.2 接口默认方法和静态方法的区别</h3> <ol><li>默认方法通过实例调用，静态方法通过接口名调用。</li> <li>默认方法可以被继承，实现类可以直接使用接口默认方法，也可以重写接口默认方法。</li> <li>静态方法不能被继承，实现类不能重写接口静态方法，只能使用接口名调用。</li></ol> <h2 id="_3-常用内置函数式接口"><a href="#_3-常用内置函数式接口" class="header-anchor">#</a> 3 常用内置函数式接口</h2> <h3 id="_3-1-内置函数式接口的由来"><a href="#_3-1-内置函数式接口的由来" class="header-anchor">#</a> 3.1 内置函数式接口的由来</h3> <p>我们知道使用Lambda表达式的前提是需要有函数式接口。而Lambda使用时不关心接口名，抽象方法名，只关心抽象方法的参数列表和返回值类型。因此为了让我们使用Lambda方便，JDK提供了大量常用的函数式接口。</p> <h3 id="_3-2-常用函数式接口的介绍"><a href="#_3-2-常用函数式接口的介绍" class="header-anchor">#</a> 3.2 常用函数式接口的介绍</h3> <p>它们主要在<code>java.util.function</code>包中。下面是最常用的几个接口。</p> <h4 id="supplier-生产者"><a href="#supplier-生产者" class="header-anchor">#</a> Supplier:生产者</h4> <p><code>java.util.function.Supplier&lt;T&gt;</code>接口，它意味着&quot;供给&quot;, 对应的Lambda表达式需要&quot;对外提供&quot;一个符合泛型类型的对象数据。</p> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token annotation punctuation">@FunctionalInterface</span>
<span class="token keyword">public</span> <span class="token keyword">interface</span> <span class="token class-name">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">abstract</span> <span class="token class-name">T</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>
</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></div></div><h4 id="consumer-消费者"><a href="#consumer-消费者" class="header-anchor">#</a> Consumer:消费者</h4> <p><code>java.util.function.Consumer&lt;T&gt;</code>接口则正好相反，它不是生产一个数据，而是消费一个数据，其数据类型由泛型参数决定。</p> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token annotation punctuation">@FunctionalInterface</span>
<span class="token keyword">public</span> <span class="token keyword">interface</span> <span class="token class-name">Consumer</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">abstract</span> <span class="token keyword">void</span> <span class="token function">accept</span><span class="token punctuation">(</span><span class="token class-name">T</span> t<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">/** 该方法使得两个Consumer先后调用 c1.andThen(c2).accept(t) **/</span>
<span class="token keyword">default</span> <span class="token class-name">Consumer</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token function">andThen</span><span class="token punctuation">(</span><span class="token class-name">Consumer</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token operator">?</span> <span class="token keyword">super</span> <span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> after<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token class-name">Objects</span><span class="token punctuation">.</span><span class="token function">requireNonNull</span><span class="token punctuation">(</span>after<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token class-name">T</span> t<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token punctuation">{</span> <span class="token function">accept</span><span class="token punctuation">(</span>t<span class="token punctuation">)</span><span class="token punctuation">;</span> after<span class="token punctuation">.</span><span class="token function">accept</span><span class="token punctuation">(</span>t<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></div></div><ul><li>默认方法: andThen
<ul><li>如果一个方法的参数和返回值全都是 Consumer 类型，那么就可以实现效果：消费一个数据的时候，首先做一个操作，然后再做一个操作，实现组合。而这个方法就是 Consumer 接口中的default方法 andThen</li> <li>要想实现组合，需要两个或多个Lambda表达式即可，而 andThen 的语义正是&quot;一步接一步&quot;操作</li></ul></li></ul> <h4 id="function-类型转换"><a href="#function-类型转换" class="header-anchor">#</a> Function:类型转换</h4> <p><code>java.util.function.Function&lt;T,R&gt;</code>接口用来根据一个类型的数据得到另一个类型的数据，前者称为前置条件，后者称为后置条件。有参数有返回值。</p> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token annotation punctuation">@FunctionalInterface</span>
<span class="token keyword">public</span> <span class="token keyword">interface</span> <span class="token class-name">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">,</span> <span class="token class-name">R</span><span class="token punctuation">&gt;</span></span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">abstract</span> <span class="token class-name">R</span> <span class="token function">apply</span><span class="token punctuation">(</span><span class="token class-name">T</span> t<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">default</span> <span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">V</span><span class="token punctuation">&gt;</span></span> <span class="token class-name">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">V</span><span class="token punctuation">,</span> <span class="token class-name">R</span><span class="token punctuation">&gt;</span></span> <span class="token function">compose</span><span class="token punctuation">(</span><span class="token class-name">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token operator">?</span> <span class="token keyword">super</span> <span class="token class-name">V</span><span class="token punctuation">,</span> <span class="token operator">?</span> <span class="token keyword">extends</span> <span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> before<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token class-name">Objects</span><span class="token punctuation">.</span><span class="token function">requireNonNull</span><span class="token punctuation">(</span>before<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token class-name">V</span> v<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token function">apply</span><span class="token punctuation">(</span>before<span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</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></div></div><ul><li>默认方法: andThen
<ul><li>Function 接口中有一个默认的 andThen 方法，用来进行组合操作</li> <li>该方法同样用于&quot;先做什么，再做什么&quot;的场景，和 Consumer 中的 andThen 差不多</li></ul></li></ul> <h4 id="predicate-判断"><a href="#predicate-判断" class="header-anchor">#</a> Predicate:判断</h4> <p>有时候我们需要对某种类型的数据进行判断，从而得到一个boolean值结果。这时可以使用<code>java.util.function.Predicate&lt;T&gt;</code>接口。</p> <div class="language-java line-numbers-mode"><pre class="language-java"><code><span class="token annotation punctuation">@FunctionalInterface</span>
<span class="token keyword">public</span> <span class="token keyword">interface</span> <span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token punctuation">{</span>
<span class="token keyword">public</span> <span class="token keyword">abstract</span> <span class="token keyword">boolean</span> <span class="token function">test</span><span class="token punctuation">(</span><span class="token class-name">T</span> t<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">/** &amp;&amp; **/</span>
<span class="token keyword">default</span> <span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token function">and</span><span class="token punctuation">(</span><span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token operator">?</span> <span class="token keyword">super</span> <span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> other<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token class-name">Objects</span><span class="token punctuation">.</span><span class="token function">requireNonNull</span><span class="token punctuation">(</span>other<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span>t<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token function">test</span><span class="token punctuation">(</span>t<span class="token punctuation">)</span> <span class="token operator">&amp;&amp;</span> other<span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>t<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment">/** ! **/</span>
<span class="token keyword">default</span> <span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token function">negate</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span>t<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token operator">!</span><span class="token function">test</span><span class="token punctuation">(</span>t<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment">/** || **/</span>
<span class="token keyword">default</span> <span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token function">or</span><span class="token punctuation">(</span><span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token operator">?</span> <span class="token keyword">super</span> <span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> other<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token class-name">Objects</span><span class="token punctuation">.</span><span class="token function">requireNonNull</span><span class="token punctuation">(</span>other<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span>t<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token function">test</span><span class="token punctuation">(</span>t<span class="token punctuation">)</span> <span class="token operator">||</span> other<span class="token punctuation">.</span><span class="token function">test</span><span class="token punctuation">(</span>t<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">static</span> <span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token class-name">Predicate</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">T</span><span class="token punctuation">&gt;</span></span> <span class="token function">isEqual</span><span class="token punctuation">(</span><span class="token class-name">Object</span> targetRef<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> <span class="token punctuation">(</span><span class="token keyword">null</span> <span class="token operator">==</span> targetRef<span class="token punctuation">)</span>
<span class="token operator">?</span> <span class="token class-name">Objects</span><span class="token operator">::</span><span class="token function">isNull</span>
<span class="token operator">:</span> object <span class="token operator">-&gt;</span> targetRef<span class="token punctuation">.</span><span class="token function">equals</span><span class="token punctuation">(</span>object<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><ul><li><p>默认方法: and</p> <ul><li>既然是条件判断，就会存在与、或、非三种常见的逻辑关系。其中将两个 Predicate 条件使用&quot;与&quot;逻辑连接起来实现&quot;并且&quot;的效果时，可以使用default方法 and</li></ul></li> <li><p>默认方法: or</p> <ul><li>与 and 的&quot;与&quot;类似，默认方法 or 实现逻辑关系中的&quot;或&quot;</li></ul></li> <li><p>默认方法: negate</p> <ul><li>&quot;与&quot;、&quot;或&quot;已经了解了，剩下的&quot;非&quot;（取反）也会简单。它是执行了test方法之后，对结果boolean值进行&quot;!&quot;取反而已。一定要在 test 方法调用之前调用 negate 方法</li></ul></li></ul> <h2 id="_4-方法引用"><a href="#_4-方法引用" class="header-anchor">#</a> 4 方法引用</h2> <p>方法引用的注意事项</p> <ol><li>被引用的方法，参数要和接口中抽象方法的参数一样</li> <li>当接口抽象方法有返回值时，被引用的方法也必须有返回值</li></ol> <h3 id="_4-1-方法引用简化lambda"><a href="#_4-1-方法引用简化lambda" class="header-anchor">#</a> 4.1 方法引用简化Lambda</h3> <p>使用Lambda表达式求一个数组的和</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">Demo2</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 comment">// 将数组进行求和</span>
<span class="token function">printSum</span><span class="token punctuation">(</span><span class="token punctuation">(</span>arr<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token punctuation">{</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> arr<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 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">&quot;sum = &quot;</span> <span class="token operator">+</span> sum<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">// 使用已有的方法进行方法引用(让已实现的方法复用)</span>
<span class="token comment">// 类名::静态方法</span>
<span class="token function">printSum</span><span class="token punctuation">(</span><span class="token class-name">Demo2</span><span class="token operator">::</span><span class="token function">getSum</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment">/** 已有的求和方法 **/</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">getSum</span><span class="token punctuation">(</span><span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span> arr<span class="token punctuation">)</span><span class="token punctuation">{</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> arr<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 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">&quot;sum = &quot;</span> <span class="token operator">+</span> sum<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token comment">/** 使用消费者函数式接口 **/</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token keyword">void</span> <span class="token function">printSum</span><span class="token punctuation">(</span><span class="token class-name">Consumer</span><span class="token operator">&lt;</span><span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token operator">&gt;</span> consumer<span class="token punctuation">)</span><span class="token punctuation">{</span>
<span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span> arr <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token punctuation">{</span><span class="token number">11</span><span class="token punctuation">,</span> <span class="token number">22</span><span class="token punctuation">,</span> <span class="token number">33</span><span class="token punctuation">,</span> <span class="token number">44</span><span class="token punctuation">}</span><span class="token punctuation">;</span>
consumer<span class="token punctuation">.</span><span class="token function">accept</span><span class="token punctuation">(</span>arr<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></div></div><h3 id="_4-2-方法引用格式"><a href="#_4-2-方法引用格式" class="header-anchor">#</a> 4.2 方法引用格式</h3> <ul><li>符号表示: <code>::</code></li> <li>符号说明: 双冒号为方法引用运算符，而它所在的表达式被称为方法引用。</li> <li>应用场景: 如果Lambda所要实现的方案 , 已经有其他方法存在相同方案，那么则可以使用方法引用</li></ul> <h3 id="_4-3-常见引用方式"><a href="#_4-3-常见引用方式" class="header-anchor">#</a> 4.3 常见引用方式</h3> <p>方法引用在JDK 8中使用方式相当灵活，有以下几种形式：</p> <ol><li><code>instanceName::methodName</code> 对象::方法名</li> <li><code>ClassName::staticMethodName</code> 类名::静态方法</li> <li><code>ClassName::methodName</code> 类名::普通方法</li> <li><code>ClassName::new</code> 类名::new 调用的构造器</li> <li><code>TypeName[]::new</code> String[]::new 调用数组的构造器</li></ol> <h4 id="对象-成员方法"><a href="#对象-成员方法" class="header-anchor">#</a> 对象::成员方法</h4> <p>这是最常见的一种用法。如果一个类中已经存在了一个成员方法，则可以通过对象名引用成员方法，代码为：</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">MethodRefDemo</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">Date</span> now <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Date</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment">// 使用Lambda表达式获取当前时间</span>
<span class="token class-name">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">Long</span><span class="token punctuation">&gt;</span></span> su1 <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-&gt;</span> now<span class="token punctuation">.</span><span class="token function">getTime</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>su1<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">// 使用方法引用获取当前时间</span>
<span class="token class-name">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">Long</span><span class="token punctuation">&gt;</span></span> su2 <span class="token operator">=</span> now<span class="token operator">::</span><span class="token function">getTime</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>su2<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></div></div><h4 id="类名-静态方法"><a href="#类名-静态方法" class="header-anchor">#</a> 类名::静态方法</h4> <p>由于在<code>java.lang.System</code>类中已经存在了静态方法 currentTimeMillis，所以当我们需要通过Lambda来调用该方法时,可以使用方法引用, 写法是：</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">MethodRefDemo</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">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">Long</span><span class="token punctuation">&gt;</span></span> su3 <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-&gt;</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 comment">// 等同于, 调用该类的静态方法</span>
<span class="token class-name">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">Long</span><span class="token punctuation">&gt;</span></span> su4 <span class="token operator">=</span> <span class="token class-name">System</span><span class="token operator">::</span><span class="token function">currentTimeMillis</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></div></div><h4 id="类名-引用实例方法"><a href="#类名-引用实例方法" class="header-anchor">#</a> 类名::引用实例方法</h4> <p>Java面向对象中，类名只能调用静态方法，类名引用实例方法是有前提的，实际上是拿第一个参数作为方法的调用者。</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">MethodRefDemo</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">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">,</span> <span class="token class-name">Integer</span><span class="token punctuation">&gt;</span></span> f1 <span class="token operator">=</span> <span class="token punctuation">(</span>str<span class="token punctuation">)</span> <span class="token operator">-&gt;</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 punctuation">;</span>
<span class="token comment">// 等同于, 将参数作为调用者去调用方法, 然后接收对应数据类型的返回值</span>
<span class="token class-name">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">,</span> <span class="token class-name">Integer</span><span class="token punctuation">&gt;</span></span> f2 <span class="token operator">=</span> <span class="token class-name">String</span><span class="token operator">::</span><span class="token function">length</span><span class="token punctuation">;</span>
<span class="token class-name">BiFunction</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">,</span> <span class="token class-name">Integer</span><span class="token punctuation">,</span> <span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> f3 <span class="token operator">=</span> <span class="token class-name">String</span><span class="token operator">::</span><span class="token function">substring</span><span class="token punctuation">;</span>
<span class="token comment">// 等同于, 将第一个参数作为调用者, 第二个参数作为参数, 然后接收对应数据类型的返回值</span>
<span class="token class-name">BiFunction</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">,</span> <span class="token class-name">Integer</span><span class="token punctuation">,</span> <span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> f4 <span class="token operator">=</span> <span class="token punctuation">(</span>str<span class="token punctuation">,</span> index<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> str<span class="token punctuation">.</span><span class="token function">substring</span><span class="token punctuation">(</span>index<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></div></div><h4 id="类名-new"><a href="#类名-new" class="header-anchor">#</a> 类名::new</h4> <p>由于构造器的名称与类名完全一样。所以构造器引用使用<code>类名称::new</code>的格式表示</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">MethodRefDemo</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 comment">// 使用无参构造器实例一个String类</span>
<span class="token class-name">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> s1 <span class="token operator">=</span> <span class="token class-name">String</span><span class="token operator">::</span><span class="token keyword">new</span><span class="token punctuation">;</span>
<span class="token comment">// 等同于</span>
<span class="token class-name">Supplier</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> s2 <span class="token operator">=</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
s1<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 comment">// 把具体地调用体现在了接口上</span>
<span class="token comment">// 使用一个参数的构造器实例一个String类</span>
<span class="token class-name">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">,</span> <span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> s3 <span class="token operator">=</span> <span class="token class-name">String</span><span class="token operator">::</span><span class="token keyword">new</span><span class="token punctuation">;</span>
<span class="token comment">// 等同于</span>
<span class="token class-name">Function</span><span class="token generics"><span class="token punctuation">&lt;</span><span class="token class-name">String</span><span class="token punctuation">,</span> <span class="token class-name">String</span><span class="token punctuation">&gt;</span></span> s4 <span class="token operator">=</span> <span class="token punctuation">(</span>str<span class="token punctuation">)</span> <span class="token operator">-&gt;</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span><span class="token punctuation">;</span>
s3<span class="token punctuation">.</span><span class="token function">apply</span><span class="token punctuation">(</span><span class="token string">&quot;张三&quot;</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="数组-new"><a href="#数组-new" class="header-anchor">#</a> 数组::new</h4> <p>数组也是 Object 的子类对象，所以同样具有构造器，只是语法稍有不同</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">MethodRefDemo</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">Function</span><span class="token operator">&lt;</span><span class="token class-name">Integer</span><span class="token punctuation">,</span> <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token operator">&gt;</span> f <span class="token operator">=</span> length <span class="token operator">-&gt;</span> <span class="token keyword">new</span> <span class="token keyword">int</span><span class="token punctuation">[</span>length<span class="token punctuation">]</span><span class="token punctuation">;</span>
<span class="token comment">// 等同于</span>
<span class="token class-name">Function</span><span class="token operator">&lt;</span><span class="token class-name">Integer</span><span class="token punctuation">,</span> <span class="token keyword">int</span><span class="token punctuation">[</span><span class="token punctuation">]</span><span class="token operator">&gt;</span> ff <span class="token operator">=</span> <span class="token keyword">int</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 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></div></div><h4 id="小结-2"><a href="#小结-2" class="header-anchor">#</a> 小结</h4> <p>方法引用是对Lambda表达式符合特定情况下的一种缩写，它使得我们的Lambda表达式更加的精简，也可以理解为Lambda表达式的缩写形式, 不过要注意的是方法引用只能&quot;引用&quot;已经存在的方法!</p></div></section> <footer class="page-edit"><!----> <!----></footer> <div class="page-nav"><p class="inner"><!----> <span class="next"><a href="/blogs/java/java8/java8-2.html">
JDK8 特性（二）
</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/java8-1.html#_1-lambda表达式" class="sidebar-link reco-side-_1-lambda表达式" data-v-b57cc07c>1 Lambda表达式</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_1-1-lambda标准格式" class="sidebar-link reco-side-_1-1-lambda标准格式" data-v-b57cc07c>1.1 Lambda标准格式</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_1-2-lambda初体验" class="sidebar-link reco-side-_1-2-lambda初体验" data-v-b57cc07c>1.2 Lambda初体验</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_1-3-lambda实现原理" class="sidebar-link reco-side-_1-3-lambda实现原理" data-v-b57cc07c>1.3 Lambda实现原理</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_1-4-lambda省略格式" class="sidebar-link reco-side-_1-4-lambda省略格式" data-v-b57cc07c>1.4 Lambda省略格式</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_1-5-lambda前提条件" class="sidebar-link reco-side-_1-5-lambda前提条件" data-v-b57cc07c>1.5 Lambda前提条件</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_1-6-lambda和匿名内部类对比" class="sidebar-link reco-side-_1-6-lambda和匿名内部类对比" data-v-b57cc07c>1.6 Lambda和匿名内部类对比</a></li><li class="level-2" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_2-jdk8接口增强" class="sidebar-link reco-side-_2-jdk8接口增强" data-v-b57cc07c>2 JDK8接口增强</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_2-1-增强介绍" class="sidebar-link reco-side-_2-1-增强介绍" data-v-b57cc07c>2.1 增强介绍</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_2-2-接口默认方法和静态方法的区别" class="sidebar-link reco-side-_2-2-接口默认方法和静态方法的区别" data-v-b57cc07c>2.2 接口默认方法和静态方法的区别</a></li><li class="level-2" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_3-常用内置函数式接口" class="sidebar-link reco-side-_3-常用内置函数式接口" data-v-b57cc07c>3 常用内置函数式接口</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_3-1-内置函数式接口的由来" class="sidebar-link reco-side-_3-1-内置函数式接口的由来" data-v-b57cc07c>3.1 内置函数式接口的由来</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_3-2-常用函数式接口的介绍" class="sidebar-link reco-side-_3-2-常用函数式接口的介绍" data-v-b57cc07c>3.2 常用函数式接口的介绍</a></li><li class="level-2" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_4-方法引用" class="sidebar-link reco-side-_4-方法引用" data-v-b57cc07c>4 方法引用</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_4-1-方法引用简化lambda" class="sidebar-link reco-side-_4-1-方法引用简化lambda" data-v-b57cc07c>4.1 方法引用简化Lambda</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_4-2-方法引用格式" class="sidebar-link reco-side-_4-2-方法引用格式" data-v-b57cc07c>4.2 方法引用格式</a></li><li class="level-3" data-v-b57cc07c><a href="/blogs/java/java8/java8-1.html#_4-3-常见引用方式" class="sidebar-link reco-side-_4-3-常见引用方式" data-v-b57cc07c>4.3 常见引用方式</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 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