- Identifiers must start with a letter, a currency character ($), or a connecting character such as the underscore ( _ ). Identifiers cannot start with a number!
- After the first character, identifiers can contain any combination of letters, currency characters, connecting characters, or numbers.
- In practice, there is no limit to the number of characters an identifier can contain.
- You can't use a Java keyword as an identifier. Below table lists all of the Java keywords including one new one for 5.0, enum.
- Identifiers in Java are case-sensitive; foo and FOO are two different identifiers.
int _a;
int $c;
int ______2_w;
int _$;
int this_is_a_very_detailed_name_for_an_identifier;
The following are illegal:
int :b;
int -d;
int e#;
int .f;
int 7g;
Complete List of Java Keywords (assert added in 1.4, enum added in 1.5)
| abstract | boolean | break | byte | case | catch |
| char | class | const | continue | default | do |
| double | else | extends | final | finally | float |
| for | goto | if | implements | import | instanceof |
| int | interface | long | native | new | package |
| private | protected | public | return | short | static |
| strictfp | super | switch | synchronized | this | throw |
| throws | transient | try | void | volatile | while |
| assert | enum |
