Java 字符大小是 8 位还是 16 位？
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Char size 8 bit or 16 bit?
提问by user3198603
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html, char size is 16 bit i.e 2 byte. somehow i recalled its 8 bit i.e 1 byte. To clear my doubt, i created a text file with single character "a" and saved it. Then i inspected the size of file , its 1 byte i.e 8 bit. I am confused whats the size of character ? If its 2 byte , why file size is 1 byte and if it is 1 byte why link says 2 bytes?
http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html，字符大小为 16 位，即 2 字节。不知何故，我想起了它的 8 位，即 1 个字节。为了消除我的疑问，我创建了一个带有单个字符“a”的文本文件并保存了它。然后我检查了文件的大小，它是 1 个字节，即 8 位。我很困惑字符的大小是多少？如果是 2 字节，为什么文件大小是 1 字节，如果是 1 字节，为什么链接说是 2 字节？
采纳答案by Jon Skeet
A charin Java is a UTF-16code unit. It's not necessarily a complete Unicode character, but it's effectively an unsigned 16-bit integer.
charJava 中的A是一个UTF-16代码单元。它不一定是一个完整的 Unicode 字符，但它实际上是一个无符号的 16 位整数。
When you write text to a file (or in some other way convert it into a sequence of bytes), then the data will depend on which encodingyou use. For example, if you use ASCII or ISO-8859-1 then you're very limited as to which characters you can write, but each character will only be a byte. If you use UTF-16, then each Java charwill be converted into exactly two bytes - but some Unicode characters may take four bytes (those represented by two Java charvalues).
当您将文本写入文件（或以其他方式将其转换为字节序列）时，数据将取决于您使用的编码。例如，如果您使用 ASCII 或 ISO-8859-1，那么您可以写入的字符非常有限，但每个字符只能是一个字节。如果您使用 UTF-16，那么每个 Javachar将被转换为恰好两个字节 - 但某些 Unicode 字符可能需要四个字节（由两个 Javachar值表示的那些）。
If you use UTF-8, then the length of even a single Java charin the encoded form will depend on the value.
如果您使用UTF-8，那么即使是char编码形式的单个 Java 的长度也将取决于该值。
回答by vogomatix
Note that text files really have a format/ character set associated with them. Text files will normally be saved in UTF-8 format which is 8 bits per character unless the character is "special".
请注意，文本文件确实具有与之关联的格式/字符集。文本文件通常以 UTF-8 格式保存，即每个字符 8 位，除非字符是“特殊”字符。
回答by Ali Gajani
A char in Java is 2 bytes large (as the valid value range suggests). But it doesn't necessarily mean that every representation of a character is 2 bytes long. For instance, many encodings would only reserve 1 byte for every character (or use 1 byte for the most frequent characters).If the platform default encoding is a 1-byte encoding such as ISO-8859-1 or a variable-length encoding such as UTF-8, it can easily convert that 1 byte to a single character.
Java 中的字符大小为 2 个字节（如有效值范围所示）。但这并不一定意味着字符的每个表示都是 2 个字节长。例如，许多编码只会为每个字符保留 1 个字节（或为最频繁的字符使用 1 个字节）。如果平台默认编码是 1 字节编码，例如 ISO-8859-1 或可变长度编码，例如作为 UTF-8，它可以轻松地将 1 个字节转换为单个字符。
回答by snr
There is a contemporary way to learn its size. Just print with BYTES.
有一种现代的方式来了解它的大小。只需打印BYTES.
System.out.println(Character.BYTES);
It results in 2
它导致 2
