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Java标识符

[英]java identifiers

原文 2010-06-30 07:16:44 8 2 java

Everywhere is said that a Java identifier can start with all characters (but not digits) including $ and _ 到处都说Java标识符可以以包括$和_所有字符（但不能是数字）开头。

but I noticed that methods like isJavaIdentifierStart returns true also for other chars like § , £ , € etc 但是我注意到像isJavaIdentifierStart这样的方法对于§ ， £ ， €等其他字符也返回true

Is however correct starting an identifier with there characters? 但是，以那里的字符开头的标识符正确吗？

2 个解决方案

If isJavaIdentifierStart returns true for it, then by definition , it's a valid Java identifier starting character, because that's how the specification defines it : 如果isJavaIdentifierStart返回true，那么根据定义 ，它是一个有效的Java标识符起始字符，因为这是规范对其进行定义的方式：

Identifier: 标识符：
IdentifierChars but not a Keyword or BooleanLiteral or NullLiteral IdentifierChars，但不是关键字，BooleanLiteral或NullLiteral
IdentifierChars: IdentifierChars：
JavaLetter JavaLetter
IdentifierChars JavaLetterOrDigit 标识符字符JavaLetterOrDigit
JavaLetter: JavaLetter：
any Unicode character that is a Java letter (see below) 任何Java字母的Unicode字符（请参见下文）
JavaLetterOrDigit: JavaLetterOrDigit：
any Unicode character that is a Java letter-or-digit (see below) Java字母或数字的任何Unicode字符（请参见下文）
... ...
A "Java letter" is a character for which the method Character.isJavaIdentifierStart(int) returns true . “ Java字母”是一个字符，其Character.isJavaIdentifierStart(int)方法返回true 。

The method means what it says. 该方法说明了它的意思。

It returns false for § , because it's not a letter, Character.getType('§') is not Character.LETTER_NUMBER , it's not a currency symbol, and it's not a connecting punctuation character. 它为§返回false，因为它不是字母， Character.getType('§')不是Character.LETTER_NUMBER ，不是货币符号，也不是连接标点符号。

It is true for the two currency symbols, because that is a specific criterion. 这是两个货币符号的对，因为这是一个特定的标准。