An identifier in Java can denote a variable or method or class name or package or an interface. An identifier allows the Programmer to refer the value from a different part of the program.
int magoes = 10;
Whenever, 10 is required in the code, the programmer can use the identifier mangoes.
Java comes with clear cut rules to name an identifier. Java follows the same rules of C/C++.
Rules of Identifiers Java
- Should be single word. That is spaces are not allowed.
Example: mangoprice is valid but mango price is not valid.
- Should start with a letter (alphabet) or underscore or $ symbol.
Example: price, _price and $price are valid identifiers.
- Should not be a keyword of Java as keyword carries special meaning to the compiler.
Example: class or void etc.
- Should not start with a digit but digit can be in the middle or at the end.
Example: 5mangoescost is not valid and mango5cost and mangocost5 are valid.
- Length of an identifier in Java can be of 65,535 characters and all are significant.
- Identifiers are case-sensitive. That is both mango and Mango are treated differently.
- Can contain all uppercase letters or lowercase letters or a mixture.
Note: Always choose the identifier a meaningful word. Suppose you would like to store the number of mangoes in the code, write as
int numberOfMangoes = 10;
The above statement can also be written as
int x = 10;
The problem in the above statement is x should be remembered for the number of mangoes which may be tedious if variables are many.
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