什么是Java的内部代表String？修改UTF-8？ UTF-16？

问题描述

一个是：

，它说：

另一个是：

，它说：

修改的UTF-8？还是UTF-16？哪一个是正确的？ Java在内存中使用多少字节？

请让我知道哪一个是正确的，它使用了多少个字节。

解决方案

Java中String和StringBuilder等的表示是UTF-16

序列化字符串默认使用UTF-8。

and it says:

The other is:

and it says:

Modified UTF-8? Or UTF-16? Which one is correct? And how many bytes does Java use for a char in memory?

Please let me know which one is correct and how many bytes it uses.

解决方案

The representation for String and StringBuilder etc in Java is UTF-16

http://java.sun.com/javase/technologies/core/basic/intl/faq.jsp

At the JVM level, if you are using -XX:+UseCompressedStrings (which is default for some updates of Java 6) The actual in-memory representation can be 8-bit, ISO-8859-1 but only for strings which do not need UTF-16 encoding.

http://www.oracle.com/technetwork/java/javase/tech/vmoptions-jsp-140102.html

Serialized Strings use UTF-8 by default.

A char is always two bytes, if you ignore the need for padding in an Object.

Note: a code point (which allows character > 65535) can use one or two characters, i.e. 2 or 4 bytes.

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