如何将字符转换为字符串? [英] How to convert a char to a String?

问题描述

我有一个 char，我需要一个 String.我如何从一种转换到另一种?

I have a char and I need a String. How do I convert from one to the other?

推荐答案

您可以使用 Character.toString(char).请注意，此方法仅返回对 String.valueOf(char)，同样有效.

You can use Character.toString(char). Note that this method simply returns a call to String.valueOf(char), which also works.

正如其他人所指出的，字符串连接也可以作为一种快捷方式:

As others have noted, string concatenation works as a shortcut as well:

String s = "" + 's';

但这可以归结为:

String s = new StringBuilder().append("").append('s').toString();

效率较低，因为 StringBuilder 由 char[] 支持(由 StringBuilder() 到 16)，仅用于由结果 String 防御性复制该数组.

which is less efficient because the StringBuilder is backed by a char[] (over-allocated by StringBuilder() to 16), only for that array to be defensively copied by the resulting String.

String.valueOf(char) 通过将 char 包装在一个单元素数组中并将其传递给包私有构造函数 String(char[], boolean)，避免了数组复制.

String.valueOf(char) "gets in the back door" by wrapping the char in a single-element array and passing it to the package private constructor String(char[], boolean), which avoids the array copy.

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