转换 'ArrayList<String>到 Java 中的 'String[]' [英] Converting &#39;ArrayList&lt;String&gt; to &#39;String[]&#39; in Java

问题描述

如何在 Java 中将 ArrayList 对象转换为 String[] 数组?

How might I convert an ArrayList<String> object to a String[] array in Java?

推荐答案

List<String> list = ..;
String[] array = list.toArray(new String[0]);

例如:

List<String> list = new ArrayList<String>();
//add some stuff
list.add("android");
list.add("apple");
String[] stringArray = list.toArray(new String[0]);

不传递任何参数的toArray() 方法返回Object[].所以你必须传递一个数组作为参数，它将用列表中的数据填充并返回.您也可以传递一个空数组，但您也可以传递一个具有所需大小的数组.

The toArray() method without passing any argument returns Object[]. So you have to pass an array as an argument, which will be filled with the data from the list, and returned. You can pass an empty array as well, but you can also pass an array with the desired size.

重要更新:上面的代码原本使用了new String[list.size()].但是，这篇博文 揭示了由于 JVM 优化，使用 newString[0] 现在更好了.

Important update: Originally the code above used new String[list.size()]. However, this blogpost reveals that due to JVM optimizations, using new String[0] is better now.

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