language fundamentals
Identifiers:- A name in java program is called identifier it may be class name, method name, variable name and label name.
Example:-
Class Test
{
public static void main(String args[])
{
int x=10;
}
}
- Test:- class name.
- Main:- method name.
- String:- predefined class name.
- args:- variable name.
- X:- variable name.
Rules for defining Java Identifiers:- There are certain rules for defining a valid java identifier. These rules must be followed; otherwise we get compile-time error. These rules are also valid for other languages like C,C++.
- The only allowed characters for identifiers are all alphanumeric characters ([A-Z],[a-z],[0-9]), ‘$‘(dollar sign) and ‘_‘ (underscore).For example “daisy@” is not a valid java identifier as it contain ‘@’ special character.
- Identifiers should not start with digits([0-9]). For example “123daisy” is a not a valid java identifier.
- Java identifiers are case-sensitive.
- There is no limit on the length of the identifier but it is advisable to use an optimum length of 4 – 15 letters only.
- Reserved Words can’t be used as an identifier. For example “int while = 20;” is an invalid statement as while is a reserved word.