java - java中变量的命名限制

Question

为什么 Java 变量名中不允许使用特殊字符($、_ 除外)？

Answer 1

事实并非如此——许多特殊字符实际上对标识符有效。它被定义为 in the JLS #3.8 :

An identifier is an unlimited-length sequence of Java letters and Java digits, the first of which must be a Java letter.
[...]
A "Java letter" is a character for which the method Character.isJavaIdentifierStart(int) returns true.
A "Java letter-or-digit" is a character for which the method Character.isJavaIdentifierPart(int) returns true.

例如，这是一个有效的变量名:

String sçèêûá¢é£¥ = "bc";

您可以使用这个简单的代码查看所有有效字符:

public static void main(String args[]) {
    for (int i = 0; i < Character.MAX_VALUE; i++) {
        if (Character.isJavaIdentifierPart(i)) {
            System.out.println("i = " + i + ": " + (char) i);
        }
    }
}

ps:很好的例子on @PeterLawrey's blog