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class="title">二、Java基础</span><span class="arrow down"></span></button><ul class="sidebar-links"><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.1 Java概述及环境配置</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.2 Java语法基础</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable active"><!----><span class="title">2.3 数组&字符串</span><span class="arrow down"></span></button><ul class="sidebar-links"><li><!--[--><a href="/array/array.html" class="nav-link sidebar-link sidebar-page" aria-label="掌握Java数组"><!---->掌握Java数组<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/array/double-array.html" class="nav-link sidebar-link sidebar-page" aria-label="掌握Java二维数组"><!---->掌握Java二维数组<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/array/print.html" class="nav-link sidebar-link sidebar-page" aria-label="打印Java数组"><!---->打印Java数组<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/string-source.html" class="nav-link sidebar-link sidebar-page" aria-label="解读String类源码"><!---->解读String类源码<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/immutable.html" class="nav-link sidebar-link sidebar-page" aria-label="String为什么不可变"><!---->String为什么不可变<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/constant-pool.html" class="nav-link sidebar-link sidebar-page" aria-label="深入理解Java字符串常量池"><!---->深入理解Java字符串常量池<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/intern.html" class="nav-link sidebar-link sidebar-page" aria-label="详解 String.intern 方法"><!---->详解 String.intern 方法<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/builder-buffer.html" class="nav-link sidebar-link sidebar-page" aria-label="StringBuilder和StringBuffer"><!---->StringBuilder和StringBuffer<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/equals.html" class="nav-link sidebar-link sidebar-page" aria-label="String相等判断"><!---->String相等判断<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a href="/string/join.html" class="nav-link sidebar-link sidebar-page" aria-label="String拼接"><!---->String拼接<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li><li><!--[--><a aria-current="page" href="/string/split.html" class="router-link-active router-link-exact-active nav-link active sidebar-link sidebar-page active" aria-label="String拆分"><!---->String拆分<!----></a><ul class="sidebar-sub-headers"></ul><!--]--></li></ul></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.4 面向对象编程</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.5 集合框架（容器）</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.6 Java IO</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.7 异常处理</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.8 常用工具类</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.9 Java新特性</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.10 网络编程</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.11 NIO</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.12 Java重要知识点</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.13 并发编程</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">2.14 JVM</span><span class="arrow end"></span></button><!----></section></li></ul></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">三、Java进阶</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">四、数据库</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">五、计算机基础</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">六、求职面试</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">七、学习建议</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">八、知识库搭建</span><span class="arrow end"></span></button><!----></section></li><li><section class="sidebar-group"><button class="sidebar-heading clickable"><!----><span class="title">九、联系作者</span><span class="arrow end"></span></button><!----></section></li></ul><!--[--><!----><!--]--></aside><!--[--><main class="page" id="main-content"><!--[--><!----><nav class="breadcrumb disable"></nav><div class="page-title"><h1><!---->如何在Java中拆分字符串：详解String类的split()方法</h1><div class="page-info"><span class="page-author-info" aria-label="作者🖊" data-balloon-pos="down"><svg xmlns="http://www.w3.org/2000/svg" class="icon author-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="author icon"><path d="M649.6 633.6c86.4-48 147.2-144 147.2-249.6 0-160-128-288-288-288s-288 128-288 288c0 108.8 57.6 201.6 147.2 249.6-121.6 48-214.4 153.6-240 288-3.2 9.6 0 19.2 6.4 25.6 3.2 9.6 12.8 12.8 22.4 12.8h704c9.6 0 19.2-3.2 25.6-12.8 6.4-6.4 9.6-16 6.4-25.6-25.6-134.4-121.6-240-243.2-288z"></path></svg><span><a class="page-author-item" href="/about-the-author/" target="_blank" rel="noopener noreferrer">沉默王二</a></span><span property="author" content="沉默王二"></span></span><!----><span class="page-date-info" aria-label="写作日期📅" data-balloon-pos="down"><svg xmlns="http://www.w3.org/2000/svg" class="icon calendar-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="calendar icon"><path d="M716.4 110.137c0-18.753-14.72-33.473-33.472-33.473-18.753 0-33.473 14.72-33.473 33.473v33.473h66.993v-33.473zm-334.87 0c0-18.753-14.72-33.473-33.473-33.473s-33.52 14.72-33.52 33.473v33.473h66.993v-33.473zm468.81 33.52H716.4v100.465c0 18.753-14.72 33.473-33.472 33.473a33.145 33.145 0 01-33.473-33.473V143.657H381.53v100.465c0 18.753-14.72 33.473-33.473 33.473a33.145 33.145 0 01-33.473-33.473V143.657H180.6A134.314 134.314 0 0046.66 277.595v535.756A134.314 134.314 0 00180.6 947.289h669.74a134.36 134.36 0 00133.94-133.938V277.595a134.314 134.314 0 00-133.94-133.938zm33.473 267.877H147.126a33.145 33.145 0 01-33.473-33.473c0-18.752 14.72-33.473 33.473-33.473h736.687c18.752 0 33.472 14.72 33.472 33.473a33.145 33.145 0 01-33.472 33.473z"></path></svg><span><!----></span><meta property="datePublished" content="2021-07-13T07:01:13.000Z"></span><span class="page-category-info" aria-label="分类🌈" data-balloon-pos="down"><svg xmlns="http://www.w3.org/2000/svg" class="icon category-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="category icon"><path d="M148.41 106.992h282.176c22.263 0 40.31 18.048 40.31 40.31V429.48c0 22.263-18.047 40.31-40.31 40.31H148.41c-22.263 0-40.311-18.047-40.311-40.31V147.302c0-22.263 18.048-40.31 40.311-40.31zM147.556 553.478H429.73c22.263 0 40.311 18.048 40.311 40.31v282.176c0 22.263-18.048 40.312-40.31 40.312H147.555c-22.263 0-40.311-18.049-40.311-40.312V593.79c0-22.263 18.048-40.311 40.31-40.311zM593.927 106.992h282.176c22.263 0 40.31 18.048 40.31 40.31V429.48c0 22.263-18.047 40.31-40.31 40.31H593.927c-22.263 0-40.311-18.047-40.311-40.31V147.302c0-22.263 18.048-40.31 40.31-40.31zM730.22 920.502H623.926c-40.925 0-74.22-33.388-74.22-74.425V623.992c0-41.038 33.387-74.424 74.425-74.424h222.085c41.038 0 74.424 33.226 74.424 74.067v114.233c0 10.244-8.304 18.548-18.547 18.548s-18.548-8.304-18.548-18.548V623.635c0-20.388-16.746-36.974-37.33-36.974H624.13c-20.585 0-37.331 16.747-37.331 37.33v222.086c0 20.585 16.654 37.331 37.126 37.331H730.22c10.243 0 18.547 8.304 18.547 18.547 0 10.244-8.304 18.547-18.547 18.547z"></path></svg><span class="page-category-item category0 clickable" role="navigation">Java核心</span><meta property="articleSection" content="Java核心"></span><span class="page-tag-info" aria-label="标签🏷" data-balloon-pos="down"><svg xmlns="http://www.w3.org/2000/svg" class="icon tag-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="tag icon"><path d="M939.902 458.563L910.17 144.567c-1.507-16.272-14.465-29.13-30.737-30.737L565.438 84.098h-.402c-3.215 0-5.726 1.005-7.634 2.913l-470.39 470.39a10.004 10.004 0 000 14.164l365.423 365.424c1.909 1.908 4.42 2.913 7.132 2.913s5.223-1.005 7.132-2.913l470.39-470.39c2.01-2.11 3.014-5.023 2.813-8.036zm-240.067-72.121c-35.458 0-64.286-28.828-64.286-64.286s28.828-64.285 64.286-64.285 64.286 28.828 64.286 64.285-28.829 64.286-64.286 64.286z"></path></svg><span class="page-tag-item tag5 clickable" role="navigation">数组&字符串</span><meta property="keywords" content="数组&字符串"></span><span class="page-word-info" aria-label="字数🔠" data-balloon-pos="down"><svg xmlns="http://www.w3.org/2000/svg" class="icon word-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="word icon"><path d="M518.217 432.64V73.143A73.143 73.143 0 01603.43 1.097a512 512 0 01419.474 419.474 73.143 73.143 0 01-72.046 85.212H591.36a73.143 73.143 0 01-73.143-73.143z"></path><path d="M493.714 566.857h340.297a73.143 73.143 0 0173.143 85.577A457.143 457.143 0 11371.566 117.76a73.143 73.143 0 0185.577 73.143v339.383a36.571 36.571 0 0036.571 36.571z"></path></svg><span>约 2138 字</span><meta property="wordCount" content="2138"></span><span class="page-reading-time-info" aria-label="阅读时间⌛" data-balloon-pos="down"><svg xmlns="http://www.w3.org/2000/svg" class="icon timer-icon" viewBox="0 0 1024 1024" fill="currentColor" aria-label="timer icon"><path d="M799.387 122.15c4.402-2.978 7.38-7.897 7.38-13.463v-1.165c0-8.933-7.38-16.312-16.312-16.312H256.33c-8.933 0-16.311 7.38-16.311 16.312v1.165c0 5.825 2.977 10.874 7.637 13.592 4.143 194.44 97.22 354.963 220.201 392.763-122.204 37.542-214.893 196.511-220.2 389.397-4.661 5.049-7.638 11.651-7.638 19.03v5.825h566.49v-5.825c0-7.379-2.849-13.981-7.509-18.9-5.049-193.016-97.867-351.985-220.2-389.527 123.24-37.67 216.446-198.453 220.588-392.892zM531.16 450.445v352.632c117.674 1.553 211.787 40.778 211.787 88.676H304.097c0-48.286 95.149-87.382 213.728-88.676V450.445c-93.077-3.107-167.901-81.297-167.901-177.093 0-8.803 6.99-15.793 15.793-15.793 8.803 0 15.794 6.99 15.794 15.793 0 80.261 63.69 145.635 142.01 145.635s142.011-65.374 142.011-145.635c0-8.803 6.99-15.793 15.794-15.793s15.793 6.99 15.793 15.793c0 95.019-73.789 172.82-165.96 177.093z"></path></svg><span>大约 7 分钟</span><meta property="timeRequired" content="PT7M"></span></div><hr></div><!----><!----><div class="theme-hope-content"><h1 id="_4-11-string拆分" tabindex="-1"><a class="header-anchor" href="#_4-11-string拆分" aria-hidden="true">#</a> 4.11 String拆分</h1><p>“哥，我感觉字符串拆分没什么可讲的呀，直接上 String 类的 <code>split()</code> 方法不就可以了！”三妹毫不客气地说。</p><p>“假如你真的这么觉得，那可要注意了，事情远没这么简单。”我微笑着说。</p><p>假如现在有这样一串字符序列“沉默王二，一枚有趣的程序员”，需要按照中文逗号“，”进行拆分，这意味着第一串字符序列为逗号前面的“沉默王二”，第二串字符序列为逗号后面的“一枚有趣的程序员”。</p><p>“这不等于没说吗？哥！”还没等我说，三妹就打断了我。</p><p>“别着急嘛，等哥说完。”我依然保持着微笑继续说，“在拆分之前，要先进行检查，判断一下这串字符是否包含逗号，否则应该抛出异常。”</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">Test</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">String</span> cmower <span class="token operator">=</span> <span class="token string">"沉默王二，一枚有趣的程序员"</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>cmower<span class="token punctuation">.</span><span class="token function">contains</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">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"，"</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">"第一部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">+</span><span class="token string">" 第二部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">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 keyword">else</span> <span class="token punctuation">{</span>
<span class="token keyword">throw</span> <span class="token keyword">new</span> <span class="token class-name">IllegalArgumentException</span><span class="token punctuation">(</span><span class="token string">"当前字符串没有包含逗号"</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" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>“三妹你看，这段代码挺严谨的吧？”我说，“来看一下程序的输出结果。”</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>第一部分：沉默王二 第二部分：一枚有趣的程序员
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>“的确和预期完全一致。”三妹说。</p><p>“这是建立在字符串是确定的情况下，最重要的是分隔符是确定的。否则，麻烦就来了。”我说，“大约有 12 种英文特殊符号，如果直接拿这些特殊符号替换上面代码中的分隔符（中文逗号），这段程序在运行的时候就会出现以下提到的错误。”</p><ul><li>反斜杠 <code>\</code>（ArrayIndexOutOfBoundsException）</li><li>插入符号 <code>^</code>（同上）</li><li>美元符号 <code>$</code>（同上）</li><li>逗点 <code>.</code>（同上）</li><li>竖线 <code>|</code>（正常，没有出错）</li><li>问号 <code>?</code>（PatternSyntaxException）</li><li>星号 <code>*</code>（同上）</li><li>加号 <code>+</code>（同上）</li><li>左小括号或者右小括号 <code>()</code>（同上）</li><li>左方括号或者右方括号 <code>[]</code>（同上）</li><li>左大括号或者右大括号 <code>{}</code>（同上）</li></ul><p>“那遇到这些特殊符号该怎么办呢？”三妹问。</p><p>“用正则表达式。”我说，“正则表达式是一组由字母和符号组成的特殊文本，它可以用来从文本中找出满足你想要的格式的句子。”</p><p>我在 GitHub 上找打了一个开源的正则表达式学习文档，非常详细。一开始写正则表达式的时候难免会感觉到非常生疏，你可以查看一下这份文档。记不住没关系，遇到就查。</p><blockquote><p><a href="https://github.com/cdoco/learn-regex-zh" target="_blank" rel="noopener noreferrer">https://github.com/cdoco/learn-regex-zh<span><svg class="external-link-icon" 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"><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="external-link-icon-sr-only">open in new window</span></span></a></p></blockquote><p>除了这份文档，还有一份：</p><blockquote><p><a href="https://github.com/cdoco/common-regex" target="_blank" rel="noopener noreferrer">https://github.com/cdoco/common-regex<span><svg class="external-link-icon" 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"><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="external-link-icon-sr-only">open in new window</span></span></a></p></blockquote><p>作者收集了一些在平时项目开发中经常用到的正则表达式，可以直接拿来用。</p><p>“哥，你真周到。”三妹笑着说。</p><p>“好了，来用英文逗点 <code>.</code> 替换一下分隔符。”我说。</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> cmower <span class="token operator">=</span> <span class="token string">"沉默王二.一枚有趣的程序员"</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>cmower<span class="token punctuation">.</span><span class="token function">contains</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">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"\\."</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">"第一部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">+</span><span class="token string">" 第二部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">1</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" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>由于英文逗点属于特殊符号，所以在使用 <code>split()</code> 方法的时候，就需要使用正则表达式 <code>\\.</code> 而不能直接使用 <code>.</code>。</p><p>“为什么用两个反斜杠呢？”三妹问。</p><p>“因为反斜杠本身就是一个特殊字符，需要用反斜杠来转义。”我说。</p><p>当然了，你也可以使用 <code>[]</code> 来包裹住英文逗点“.”，<code>[]</code> 也是一个正则表达式，用来匹配方括号中包含的任意字符。</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code>cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"[.]"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>除此之外， 还可以使用 Pattern 类的 <code>quote()</code> 方法来包裹英文逗点“.”，该方法会返回一个使用 <code>\Q\E</code> 包裹的字符串。</p><figure><img src="https://cdn.tobebetterjavaer.com/tobebetterjavaer/images/string/split-01.png" alt="" tabindex="0" loading="lazy"><figcaption></figcaption></figure><p>来看示例：</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token class-name">Pattern</span><span class="token punctuation">.</span><span class="token function">quote</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>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>当 <code>split()</code> 方法的参数是正则表达式的时候，方法最终会执行下面这行代码：</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token keyword">return</span> <span class="token class-name">Pattern</span><span class="token punctuation">.</span><span class="token function">compile</span><span class="token punctuation">(</span>regex<span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">,</span> limit<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>也就意味着，拆分字符串有了新的选择，可以不使用 String 类的 <code>split()</code> 方法，直接用下面的方式。</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">TestPatternSplit</span> <span class="token punctuation">{</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token class-name">Pattern</span> twopart <span class="token operator">=</span> <span class="token class-name">Pattern</span><span class="token punctuation">.</span><span class="token function">compile</span><span class="token punctuation">(</span><span class="token string">"\\."</span><span class="token punctuation">)</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">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> twopart<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"沉默王二.一枚有趣的程序员"</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">"第一部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">+</span><span class="token string">" 第二部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">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" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>“为什么要把 Pattern 表达式声明称 static 的呢？”三妹问。</p><p>“由于模式是确定的，通过 static 的预编译功能可以提高程序的效率。”我说，“除此之外，还可以使用 Pattern 配合 Matcher 类进行字符串拆分，这样做的好处是可以对要拆分的字符串进行一些严格的限制，来看这段示例代码。”</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token keyword">public</span> <span class="token keyword">class</span> <span class="token class-name">TestPatternMatch</span> <span class="token punctuation">{</span>
<span class="token doc-comment comment">/**
* 使用预编译功能，提高效率
*/</span>
<span class="token keyword">private</span> <span class="token keyword">static</span> <span class="token class-name">Pattern</span> twopart <span class="token operator">=</span> <span class="token class-name">Pattern</span><span class="token punctuation">.</span><span class="token function">compile</span><span class="token punctuation">(</span><span class="token string">"(.+)\\.(.+)"</span><span class="token punctuation">)</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">checkString</span><span class="token punctuation">(</span><span class="token string">"沉默王二.一枚有趣的程序员"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">checkString</span><span class="token punctuation">(</span><span class="token string">"沉默王二."</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token function">checkString</span><span class="token punctuation">(</span><span class="token string">".一枚有趣的程序员"</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">checkString</span><span class="token punctuation">(</span><span class="token class-name">String</span> str<span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token class-name">Matcher</span> m <span class="token operator">=</span> twopart<span class="token punctuation">.</span><span class="token function">matcher</span><span class="token punctuation">(</span>str<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>m<span class="token punctuation">.</span><span class="token function">matches</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">"第一部分："</span> <span class="token operator">+</span> m<span class="token punctuation">.</span><span class="token function">group</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token string">" 第二部分："</span> <span class="token operator">+</span> m<span class="token punctuation">.</span><span class="token function">group</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 punctuation">;</span>
<span class="token punctuation">}</span> <span class="token keyword">else</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">"不匹配"</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" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>正则表达式 <code>(.+)\\.(.+)</code> 的意思是，不仅要把字符串按照英文标点的方式拆成两部分，并且英文逗点的前后要有内容。</p><p>来看一下程序的输出结果：</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code>第一部分：沉默王二 第二部分：一枚有趣的程序员
不匹配
不匹配
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>不过，使用 Matcher 来匹配一些简单的字符串时相对比较沉重一些，使用 String 类的 <code>split()</code> 仍然是首选，因为该方法还有其他一些牛逼的功能。比如说，如果你想把分隔符包裹在拆分后的字符串的第一部分，可以这样做：</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> cmower <span class="token operator">=</span> <span class="token string">"沉默王二，一枚有趣的程序员"</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>cmower<span class="token punctuation">.</span><span class="token function">contains</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">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"(?<=，)"</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">"第一部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">+</span><span class="token string">" 第二部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">1</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" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>程序输出的结果如下所示：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>第一部分：沉默王二， 第二部分：一枚有趣的程序员
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>可以看到分隔符“，”包裹在了第一部分，如果希望包裹在第二部分，可以这样做：</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"(?=，)"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>“<code>?<=</code> 和 <code>?=</code> 是什么东东啊？”三妹好奇地问。</p><p>“它其实是正则表达式中的断言模式。”我说，“你有时间的话，可以看看前面我推荐的两份开源文档。”</p><figure><img src="https://cdn.tobebetterjavaer.com/tobebetterjavaer/images/string/split-02.png" alt="" tabindex="0" loading="lazy"><figcaption></figcaption></figure><p>“<code>split()</code> 方法可以传递 2 个参数，第一个为分隔符，第二个为拆分的字符串个数。”我说。</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> cmower <span class="token operator">=</span> <span class="token string">"沉默王二，一枚有趣的程序员，宠爱他"</span><span class="token punctuation">;</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>cmower<span class="token punctuation">.</span><span class="token function">contains</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">String</span> <span class="token punctuation">[</span><span class="token punctuation">]</span> parts <span class="token operator">=</span> cmower<span class="token punctuation">.</span><span class="token function">split</span><span class="token punctuation">(</span><span class="token string">"，"</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 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">"第一部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">0</span><span class="token punctuation">]</span> <span class="token operator">+</span><span class="token string">" 第二部分："</span> <span class="token operator">+</span> parts<span class="token punctuation">[</span><span class="token number">1</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" aria-hidden="true"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>进入 debug 模式的话，可以看到以下内容：</p><figure><img src="https://cdn.tobebetterjavaer.com/tobebetterjavaer/images/string/split-03.png" alt="" tabindex="0" loading="lazy"><figcaption></figcaption></figure><p>也就是说，传递 2 个参数的时候，会直接调用 <code>substring()</code> 进行截取，第二个分隔符后的就不再拆分了。</p><p>来看一下程序输出的结果：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>第一部分：沉默王二 第二部分：一枚有趣的程序员，宠爱他
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>“没想到啊，这个字符串拆分还挺讲究的呀！”三妹感慨地说。</p><p>“是的，其实字符串拆分在实际的工作当中还是挺经常用的。前端经常会按照规则传递一长串字符序列到后端，后端就需要按照规则把字符串拆分再做处理。”我说。</p><p>“嗯，我把今天的内容温习下，二哥，你休息会。”三妹说。</p><hr><p>GitHub 上标星 7600+ 的开源知识库《<a href="https://github.com/itwanger/toBeBetterJavaer" target="_blank" rel="noopener noreferrer">二哥的 Java 进阶之路<span><svg class="external-link-icon" 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"><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="external-link-icon-sr-only">open in new window</span></span></a>》第一版 PDF 终于来了！包括Java基础语法、数组&字符串、OOP、集合框架、Java IO、异常处理、Java 新特性、网络编程、NIO、并发编程、JVM等等，共计 32 万余字，可以说是通俗易懂、风趣幽默……详情戳：<a href="https://tobebetterjavaer.com/overview/" target="_blank" rel="noopener noreferrer">太赞了，GitHub 上标星 7600+ 的 Java 教程<span><svg class="external-link-icon" 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"><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="external-link-icon-sr-only">open in new window</span></span></a></p><p>微信搜 <strong>沉默王二</strong> 或扫描下方二维码关注二哥的原创公众号沉默王二，回复 <strong>222</strong> 即可免费领取。</p><figure><img src="https://cdn.tobebetterjavaer.com/tobebetterjavaer/images/gongzhonghao.png" alt="" tabindex="0" loading="lazy"><figcaption></figcaption></figure></div><!----><footer 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