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<meta name="keywords" content="Java,字符串,String,intern,string intern,java intern,java string intern,String.intern"><meta property="og:url" content="https://tobebetterjavaer.com/string/intern.html"><meta property="og:site_name" content="Java程序员进阶之路"><meta property="og:title" content="Java 字符串优化：详解 String.intern() 方法"><meta property="og:description" content="本文详细解析了 Java 中 String.intern() 方法的工作原理和应用场景。了解 String.intern() 如何优化字符串处理性能，减少内存开销，并探讨其在实际开发中的使用技巧。深入了解字符串常量池和 String.intern() 方法之间的关联，以更好地应用于 Java 编程。"><meta property="og:type" content="article"><meta property="og:locale" content="zh-CN"><meta property="og:updated_time" content="2023-04-24T02:39:04.000Z"><meta property="article:tag" content="数组&字符串"><meta property="article:modified_time" content="2023-04-24T02:39:04.000Z"><script type="application/ld+json">{"@context":"https://schema.org","@type":"Article","headline":"Java 字符串优化：详解 String.intern() 方法","image":[""],"dateModified":"2023-04-24T02:39:04.000Z","author":[]}</script><meta name="robots" content="all"><meta name="author" content="沉默王二"><meta http-equiv="Cache-Control" content="no-cache, no-store, must-revalidate"><meta http-equiv="Pragma" content="no-cache"><meta http-equiv="Expires" content="0"><meta name="apple-mobile-web-app-capable" content="yes"><script>
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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 aria-current="page" href="/string/intern.html" class="router-link-active router-link-exact-active nav-link active sidebar-link sidebar-page active" 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 href="/string/split.html" class="nav-link sidebar-link sidebar-page" 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><!---->Java 字符串优化：详解 String.intern() 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 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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 2103 字</span><meta property="wordCount" content="2103"></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="_4-7-详解-string-intern-方法" tabindex="-1"><a class="header-anchor" href="#_4-7-详解-string-intern-方法" aria-hidden="true">#</a> 4.7 详解 String.intern() 方法</h1><p>“哥，你发给我的那篇文章我看了，结果直接把我给看得不想学 Java 了！”三妹气冲冲地说。</p><p>“哪一篇啊？”看着三妹面色沉重，我关心地问到。</p><p>“就是<a href="https://tech.meituan.com/2014/03/06/in-depth-understanding-string-intern.html" target="_blank" rel="noopener noreferrer">美团技术团队深入解析 <code>String.intern()</code> 那篇<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>啊！”三妹回答。</p><p>“哦，我想起来了，不挺好一篇文章嘛，深入浅出，精品中的精品，看完后你应该对 String 的 intern 方法彻底理解了才对呀。”</p><p>“好是好，但我就是看不懂！”三妹委屈地说，“哥，还是你亲自给我讲讲吧？”</p><p>“好吧，上次学的<a href="https://tobebetterjavaer.com/string/constant-pool.html" target="_blank" rel="noopener noreferrer">字符串常量池<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>你都搞清楚了吧？”</p><p>“嗯。”三妹微微的点了点头。</p><p>要理解美团技术团队的这篇文章，你只需要记住这几点内容：</p><p>第一，使用双引号声明的字符串对象会保存在字符串常量池中。</p><p>第二，使用 new 关键字创建的字符串对象会先从字符串常量池中找，如果没找到就创建一个，然后再在堆中创建字符串对象；如果找到了，就直接在堆中创建字符串对象。</p><p>第三，针对没有使用双引号声明的字符串对象来说，就像下面代码中的 s1 那样：</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> s1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span><span class="token string">"二哥"</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span><span class="token string">"三妹"</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>如果想把 s1 的内容也放入字符串常量池的话，可以调用 <code>intern()</code> 方法来完成。</p><p>不过，需要注意的是，Java 7 的时候，字符串常量池从永久代中移动到了堆中，虽然此时永久代还没有完全被移除。Java 8 的时候，永久代被彻底移除。</p><p>这个变化也直接影响了 <code>String.intern()</code> 方法在执行时的策略，Java 7 之前，执行 <code>String.intern()</code> 方法的时候，不管对象在堆中是否已经创建，字符串常量池中仍然会创建一个内容完全相同的新对象； Java 7 之后呢，由于字符串常量池放在了堆中，执行 <code>String.intern()</code> 方法的时候，如果对象在堆中已经创建了，字符串常量池中就不需要再创建新的对象了，而是直接保存堆中对象的引用，也就节省了一部分的内存空间。</p><p>“还没有理解清楚，二哥”，三妹很苦恼。</p><p>“嗯。。。别怕，三妹，先来猜猜这段代码输出的结果吧。”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> s1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span><span class="token string">"二哥三妹"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">String</span> s2 <span class="token operator">=</span> s1<span class="token punctuation">.</span><span class="token function">intern</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>s1 <span class="token operator">==</span> s2<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></div><p>“哥，这我完全猜不出啊，还是你直接解释吧。”三妹说。</p><p>“好吧。”</p><p>第一行代码，字符串常量池中会先创建一个“二哥三妹”的对象，然后堆中会再创建一个“二哥三妹”的对象，s1 引用的是堆中的对象。</p><p>第二行代码，对 s1 执行 <code>intern()</code> 方法，该方法会从字符串常量池中查找“二哥三妹”这个字符串是否存在，此时是存在的，所以 s2 引用的是字符串常量池中的对象。</p><p>也就意味着 s1 和 s2 的引用地址是不同的，一个来自堆，一个来自字符串常量池，所以输出的结果为 false。</p><p>“来看一下运行结果。”我说。</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>false
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>“我来画幅图，帮助你理解下。”看到三妹惊讶的表情，我耐心地说。</p><figure><img src="https://cdn.tobebetterjavaer.com/tobebetterjavaer/images/string/intern-01.png" alt="" tabindex="0" loading="lazy"><figcaption></figcaption></figure><p>“这下理解了吧？”我问三妹。</p><p>“嗯嗯，一下子就豁然开朗了！”三妹说。</p><p>“好，我们再来看下面这段代码。”</p><div class="language-java line-numbers-mode" data-ext="java"><pre class="language-java"><code><span class="token class-name">String</span> s1 <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span><span class="token string">"二哥"</span><span class="token punctuation">)</span> <span class="token operator">+</span> <span class="token keyword">new</span> <span class="token class-name">String</span><span class="token punctuation">(</span><span class="token string">"三妹"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token class-name">String</span> s2 <span class="token operator">=</span> s1<span class="token punctuation">.</span><span class="token function">intern</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>s1 <span class="token operator">==</span> s2<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></div><p>“难道也输出 false ？”三妹有点不确定。</p><p>“不，这段代码会输出 true。”我否定了三妹的猜测。</p><p>“为啥呀？”三妹迫切地想要知道答案。</p><p>第一行代码，会在字符串常量池中创建两个对象，一个是“二哥”，一个是“三妹”，然后在堆中会创建两个匿名对象“二哥”和“三妹”，最后还有一个“二哥三妹”的对象（稍后会解释），s1 引用的是堆中“二哥三妹”这个对象。</p><p>第二行代码，对 s1 执行 <code>intern()</code> 方法，该方法会从字符串常量池中查找“二哥三妹”这个对象是否存在，此时不存在的，但堆中已经存在了，所以字符串常量池中保存的是堆中这个“二哥三妹”对象的引用，也就是说，s2 和 s1 的引用地址是相同的，所以输出的结果为 true。</p><p>“来看一下运行结果。”我胸有成竹地说。</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>true
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>“我再来画幅图，帮助你理解下。”</p><figure><img src="https://cdn.tobebetterjavaer.com/tobebetterjavaer/images/string/intern-02.png" alt="" tabindex="0" loading="lazy"><figcaption></figcaption></figure><p>“哇，我明白了！”三妹长舒一口气，大有感慨 intern 也没什么难理解的意味，“不过，我有一个疑惑，“二哥三妹”这个对象是什么时候创建的呢？”</p><p>“三妹，不错嘛，能抓住问题的关键。再来解释一下 <code>String s1 = new String("二哥") + new String("三妹")</code> 这行代码。”我对三妹的表现非常开心。</p><ol><li>创建 "二哥" 字符串对象，存储在字符串常量池中。</li><li>创建 "三妹" 字符串对象，存储在字符串常量池中。</li><li>执行 <code>new String("二哥")</code>，在堆上创建一个字符串对象，内容为 "二哥"。</li><li>执行 <code>new String("三妹")</code>，在堆上创建一个字符串对象，内容为 "三妹"。</li><li>执行 <code>new String("二哥") + new String("三妹")</code>，会创建一个 StringBuilder 对象，并将 "二哥" 和 "三妹" 追加到其中，然后调用 StringBuilder 对象的 toString() 方法，将其转换为一个新的字符串对象，内容为 "二哥三妹"。这个新的字符串对象存储在堆上。</li></ol><p>也就是说，当编译器遇到 <code>+</code> 号这个操作符的时候，会将 <code>new String("二哥") + new String("三妹")</code> 这行代码编译为以下代码：</p><div class="language-text line-numbers-mode" data-ext="text"><pre class="language-text"><code>new StringBuilder().append("二哥").append("三妹").toString();
</code></pre><div class="line-numbers" aria-hidden="true"><div class="line-number"></div></div></div><p>实际执行过程如下：</p><ul><li>创建一个 StringBuilder 对象。</li><li>在 StringBuilder 对象上调用 append("二哥")，将 "二哥" 追加到 StringBuilder 中。</li><li>在 StringBuilder 对象上调用 append("三妹")，将 "三妹" 追加到 StringBuilder 中。</li><li>在 StringBuilder 对象上调用 toString() 方法，将 StringBuilder 转换为一个新的字符串对象，内容为 "二哥三妹"。</li></ul><p>关于 <a href="https://tobebetterjavaer.com/string/builder-buffer.html" target="_blank" rel="noopener noreferrer">StringBuilder<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>，我们随后会详细地讲到。今天先了解到这。</p><p>不过需要注意的是，尽管 intern 可以确保所有具有相同内容的字符串共享相同的内存空间，但也不要烂用 intern，因为任何的缓存池都是有大小限制的，不能无缘无故就占用了相对稀缺的缓存空间，导致其他字符串没有坑位可占。</p><p>另外，字符串常量池本质上是一个固定大小的 StringTable，如果放进去的字符串过多，就会造成严重的哈希冲突，从而导致链表变长，链表变长也就意味着字符串常量池的性能会大幅下降，因为要一个一个找是需要花费时间的。</p><p>“好了，三妹，关于 String 的 intern 就讲到这吧，这次理解了吧？”我问。</p><p>“哥，你真棒！”</p><p>看到三妹一点一滴的进步，我也感到由衷的开心。</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 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