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4 分钟 读完 (大约 573 个字)
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<h1 class="title is-size-3 is-size-4-mobile has-text-weight-normal">
一起学java之String简介
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<h6 id="基本概念"><a href="#基本概念" class="headerlink" title="基本概念"></a>基本概念</h6><p>1.String是一个类型,用来存储一串字符的,本质上是一个char类型的数组 </p>
<p>2.String类在java.lang包中,lang包已经默认导入,我们不需要再用import导入了 </p>
<p>3.定义及赋初始值 </p>
<a id="more"></a>
<figure class="highlight plain hljs"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line">String 变量名 = "初始值"; </span><br><span class="line"></span><br><span class="line">String 变量名 = new String("初始值");</span><br></pre></td></tr></table></figure>
<ul>
<li>第二种方法不常用,推荐使用第一种 </li>
</ul>
<p>4.字符串可以进行”+”运算,作用是连接两个字符串,也可以将字符串与基本类型的变量进行”+”运算,系统会自动将基本类型的变量转换成字符串进行连接操作 </p>
<p>5.内存中的字符串,字符串的intern()方法,字符串比较 </p>
<p>6.注意:</p>
<ul>
<li>内存中的字符串,注意代码中没有new的字符串字面常量会在编译时编译进字符串池中 </li>
<li>intern()方法,返回字符串在字符串池中的位置,或者向字符串池中注册 </li>
<li>对于引用类型,==比较地址是否相同,equals()比较内容是否相同 </li>
</ul>
<h6 id="一些操作"><a href="#一些操作" class="headerlink" title="一些操作"></a>一些操作</h6><p>1.常用的方法</p>
<table>
<thead>
<tr>
<th>方法名称</th>
<th>返回类型</th>
<th>作用</th>
</tr>
</thead>
<tbody><tr>
<td>length()</td>
<td>int</td>
<td>获取字符串长度</td>
</tr>
<tr>
<td>charAt(int)</td>
<td>char</td>
<td>获取字符串中的一个字符</td>
</tr>
<tr>
<td>indexOf(String)</td>
<td>int</td>
<td>返回传入字符串在原字符串中第一次出现的位置</td>
</tr>
<tr>
<td>startWith(String)</td>
<td>boolean</td>
<td>判断原字符串是否以传入字符串开始</td>
</tr>
<tr>
<td>endsWith(String)</td>
<td>boolean</td>
<td>判断原字符串是否以传入字符串结束</td>
</tr>
<tr>
<td>toUpperCase()</td>
<td>String</td>
<td>变大写</td>
</tr>
<tr>
<td>substring()</td>
<td>String</td>
<td>截取字符串</td>
</tr>
<tr>
<td>trim()</td>
<td>String</td>
<td>去前后空格</td>
</tr>
<tr>
<td>split()</td>
<td>String[]</td>
<td>原字符串按特定字符串分割成一个字符串数组</td>
</tr>
<tr>
<td>…</td>
<td>…</td>
<td>…</td>
</tr>
</tbody></table>
<h6 id="字符串与基本数据类型的转换"><a href="#字符串与基本数据类型的转换" class="headerlink" title="字符串与基本数据类型的转换"></a>字符串与基本数据类型的转换</h6><p>1.基本类型装换为字符串,用一个空字符串”” 与基本类型的变量相加 </p>
<p>2.基本类型转换为字符串,使用String的ValueOf方法 </p>
<p>3.字符串转换为基本类型,使用各类型的包装类,char使用字符串的charAt()方法 </p>
<table>
<thead>
<tr>
<th>基本类型</th>
<th>包装类型</th>
<th>转化方法</th>
</tr>
</thead>
<tbody><tr>
<td>int</td>
<td>Interger</td>
<td>parseInt();</td>
</tr>
<tr>
<td>byte</td>
<td>Byte</td>
<td>parseByte();</td>
</tr>
<tr>
<td>short</td>
<td>Short</td>
<td>parseShort();</td>
</tr>
<tr>
<td>long</td>
<td>Long</td>
<td>parseLong();</td>
</tr>
<tr>
<td>float</td>
<td>Float</td>
<td>parseFloat();</td>
</tr>
<tr>
<td>double</td>
<td>Double</td>
<td>parseDouble();</td>
</tr>
<tr>
<td>boolean</td>
<td>Boolean</td>
<td>parseBoolean();</td>
</tr>
</tbody></table>
<h6 id="StringBuffer和StringBuilder"><a href="#StringBuffer和StringBuilder" class="headerlink" title="StringBuffer和StringBuilder"></a>StringBuffer和StringBuilder</h6><p>1.StringBuffe在对字符串操作时效率要远高于String </p>
<p>2.StringBuffer与StringBuilder用法相似,但StringBuffer线程安全,推荐使用 </p>
<p>3.StringBuffer的insert();append();delete()方法 </p>
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<li><strong>本文标题：</strong><a href="https://blog.visutech.cn/56445.html">一起学java之String简介</a></li>
<li><strong>本文作者：</strong><a href="https://blog.visutech.cn">程振奇 | smallodd</a></li>
<li><strong>本文链接：</strong><a href="https://blog.visutech.cn/56445.html">https://blog.visutech.cn/56445.html</a></li>
<li><strong>发布时间：</strong>2013-07-10</li>
<li><strong>版权声明：</strong>本博客所有文章除特别声明外，均采用 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/deed.zh" rel="external nofollow" target="_blank">CC BY-NC-SA 4.0</a> 许可协议。转载请注明出处！
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