core java valid identifier

Java Language Fundamental

1.     Identifiers

2.     Reserved words

3.     Data Types

4.     Literals

5.     Arrays

6.     Type Of variables

7.     Var-args method

8.     Main method

9.     Command Line arguments

10. Java coding standards

Identifiers :-  A name in java program called Identifiers .

 It can be class name or variable name or method name or label name.

Ie:-

class Test {

            public static void main (String [] args){

int x=0;

}

}

 // Here Test, main and x is identifiers.

Rule to define Identifiers :-

The Allowed character  in java are :

·        A to Z

·        a to z

·        0 to 9

·        _

·        $

1.If we are using only other character, we will get compiler error.

Ie:

 All#(false)

 098_10(false)

_$_$(true)

2.Identifier can not start with digit and after that character.

Ie :

123total (false)

            Total123(true)

3. Java Identifier are case sensitive

4. Java Identifier do not have length limit , But It’s not recommended to take      more than 15 length.

5. Reserved words can’t be used as identifiers.

6. All predefine Java classes and Interface name we use as Identifiers  even though it is legal but it is not recommended.

Ie:

Class Test {

            int String=10;

            System.out.println(String);

// out put 10

}