Java String内部表示 [英] Java String internal representation

问题描述

我知道Java for String的内部表示是UTF-16。什么是java字符串表示？

另外，我知道在UTF-16字符串中，每个'character'用一个或两个16位代码单元编码。

但是，当我调试以下java代码

  String hello =Hello; 
  

变量hello是一个5字节的数组0x48，0x101，0x108，0x108，0x111
是Hello的ASCII。

如何做？

解决方案

的一个迷你java进程与这个代码：

  class Hi {
 public static void main（String args []） {
 String hello =Hello; 
 try {
 Thread.sleep（60_000）; 
} catch（InterruptedException e）{
 e.printStackTrace（）; 
} 
 
} 
} 
  

Ubuntu上的一个 gcore 内存转储。 （usign jps 获取 pid 并将其传递给gcore）

如果在使用Hexeditor的转储中找到这个： 48 65 6C 6C 6F ，则内存中的某个位置是ASCII。

但也是 48 00 65 00 6C 00 6C 这是 UTF-16 表示 String

I understand that the internal representation of Java for String is UTF-16. What is java string representation?

Also, I know that in a UTF-16 String, each 'character' is encoded with one or two 16-bit code units.

However, when I debug the following java code

String hello = "Hello";

the variable hello is an array of 5 bytes 0x48, 0x101, 0x108, 0x108, 0x111 which is ASCII for "Hello".

How can this be?

解决方案

I took a gcore dump of a mini java process with this code:

 class Hi {
    public static void main(String args[]) {
        String hello = "Hello";
        try {
            Thread.sleep(60_000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

And did a gcore memory dump on Ubuntu. (usign jps to get the pid and passed that to gcore)

If found this: 48 65 6C 6C 6F in the dump using a Hexeditor, so it is somewhere in the memory as ASCII.

But also 48 00 65 00 6C 00 6C which is part of the UTF-16 representation of the String

这篇关于Java String内部表示的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！