Using identifiers
Identifiers are used for class names, method names, and variable names.
An identifier may be any sequence of uppercase and lowercase letters, numbers, or the underscore and dollar-sign characters.
Identifiers must not begin with a number.
Java Identifiers are case-sensitive.
The following code illustrates some examples of valid identifiers:
public class Main {
public static void main(String[] argv) {
int ATEST, count, i1, $Atest, this_is_a_test;
}
}
The following code shows invalid variable names include:
public class Main {
public static void main(String[] argv){
int 2count, h-l, a/b,
}
}
If you try to compile this code, you will get the following error message:
Exception in thread "main" java.lang.Error: Unresolved compilation problems:
Syntax error on token "2", delete this token
Syntax error on token "h", = expected after this token
Syntax error on token ",", . expected
Syntax error on token ",", ; expected
at Main.main(Main.java:3)