当我们遍历拼接字符串的时候，最后会多出一个我们添加的字符(比如逗号)
可使用如下三种方法去掉最后多余的符号
<code class="language-java hljs has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background: transparent;">String str[] = { <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"3"</span>, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"4"</span> };StringBuffer buf = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> StringBuffer();<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i < str.length; i++) { buf.append(str[i]).append(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">","</span>);}<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (buf.length() > <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>) { <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//方法一 : substring</span> System.out.println(buf.substring(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, buf.length()-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>)); <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//方法二 ：replace</span> System.out.println(buf.replace(buf.length() - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, buf.length(), <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span>)); <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//方法三： deleteCharAt</span> System.out.println(buf.deleteCharAt(buf.length()-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>));}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;"></li></ul>
