Naming restrictions of variables in java

Question

Why are special characters (except `$`, `_`) not allowed in Java variable names?

Accepted Answer

This is not the case - many special characters are actually valid for identifiers. It is defined 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.

For example, this is a valid variable name:

```
String sçèêûá¢é£¥ = "bc";
```

You can see all the valid characters with this simple code:

```
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: nice examples on @PeterLawrey's blog

Naming restrictions of variables in java

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