Any name injava program is called as identifiers. It may be a variable name, a method name, a class etc.
public Static void main(String args)
NOTE:ALL THE RED WORDS ARE IDENTIFIERS.
RULES & REGULATIONS FOR DECLARING AN IDENTIFIER:
1.The following allowed characters can be taken to declare as identifiers.
2. To declare an identifier the first character shouldnot be digit.
Exa: 1234sum (invalid)
3.Reserved words never consider as identifiers
Exa: int x=10; (valid)
Int if =10; (invalid)
4.All inbuilt class & interfaces can be considered as identifier, but it is not recommended because the readability of the code reduce.
System.out.println(String) ; // 10
Here String is a valid identifier but not recomnded.
Here Runnable(an inbuilt interface) is a valid identifier, but not recommended.
5. There is no length limit of identifier.
Exa: int xxxxxxxxxxxyyyyyxz=10;