一、可变参数
- 可变参数顾名思义就是,编写一个函数的时候,可以传入一个或者多个参数
- 实际原理:根据传入的参数类型以及个数,创建一个数组,用于存储这些数据,在函数中调用的时候,也可以使用数组的形式调用,下面我们举个例子
<span class="hljs-keyword">package</span> com.newJava;<br><br><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">D152_VariableParameters</span> </span>{<br> <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span><span class="hljs-params">(String[] args)</span> </span>{<br>  System.out.println(<span class="hljs-string">"打印出了"</span>);<br>  printString();<br>  printString(<span class="hljs-string">"jsidofs"</span>,<span class="hljs-string">" josdfjs"</span>);<br> }<br> <br> <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">printString</span><span class="hljs-params">(String... strings)</span> </span>{<br>  <span class="hljs-keyword">if</span> (strings != <span class="hljs-keyword">null</span>) {<br>   <span class="hljs-keyword">int</span> size = strings.length;<br>   <span class="hljs-keyword">for</span> (<span class="hljs-keyword">int</span> i=<span class="hljs-number">0</span>; i<size; i++) {<br>    System.out.println(strings[i]);<br>   }<br>  } <span class="hljs-keyword">else</span> {<br>   System.out.println(<span class="hljs-string">"空参数也是可以的"</span>);<br>  }<br>  System.out.println(<span class="hljs-string">"空数组"</span>);<br> }<br>}<br><br></size; i++) {
- 从上面的实验上来看,即使我们没有传入任何数据,函数依然会被调用,但是传入的是一个空的数组,但不是一个null
- 一些规则:尽量不使用这种写法,如果要使用的话,需要把可变参数放到参数列表的最后面,不能放到中间或者前面。在进行重载函数的编写完之后,调用的时候要明确传入参数的类型,不要引起混淆,比如
<span class="hljs-keyword">package</span> com.newJava;<br><br><span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">D152_2_ConfuseMethodAndInvoke</span> </span>{<br> <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">print</span><span class="hljs-params">(String... a)</span> </span>{<br>  System.out.println(a[<span class="hljs-number">0</span>]);<br> }<br> <br> <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">print</span><span class="hljs-params">(<span class="hljs-keyword">int</span>... b)</span> </span>{<br>  System.out.println(b[<span class="hljs-number">1</span>]);<br> }<br> <br> <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">main</span><span class="hljs-params">(String[] args)</span> </span>{<br>  <span class="hljs-keyword">try</span> {<br>   print(<span class="hljs-keyword">null</span>);<br>  } <span class="hljs-keyword">catch</span> (Exception e) {<br>   e.printStackTrace();<br>  } <span class="hljs-keyword">finally</span> {<br>   print(<span class="hljs-string">"jdisf"</span>, <span class="hljs-string">"jdisfod"</span>);<br>  }<br> }<br>}
- 这样重载函数会引起编译器的混乱,不知道该如何重载函数。
二、多线程状态图
三、源码:
- github路径:https://github.com/ruigege66/Java/blob/master/newJava/src/com/newJava/
- CSDN:https://blog.csdn.net/weixin_44630050
- 博客园:https://www.cnblogs.com/ruigege0000/
Original: https://www.cnblogs.com/ruigege0000/p/15713534.html
Author: 心悦君兮君不知-睿
Title: Java连载153-可变参数、多线程状态图
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