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 A name in Java program is called identifier,it can be class name or variable name or method name or lable name.

Example.

             

👉 Rules of define indentifiers

1.     The only allowed charaters in Java indentifiers are:
1. A to Z
2. a to z
3. 0 to 9
4. hyphen(-)
5. dollar($)
2. if we are using any other characters we will get completime error.

 public class Main {

  public static void main(String[] args) {

    // Good

    int 455 = 60;

    // OK, but not so easy to understand what m actually is

    int m = 60;

    

    System.out.println(455);

    System.out.println(m);

  }

}

Datatypes in Java 

Array In Java

OUTPUT 

   3. Indentifiers can't start with digit.

            Ex.

                    123abc  - Error

                    abc123 - Ok

  4. Java identifiers is casesensitive 

            Ex.

                    Class Test

                        {

                       int Number  = 10;

                        int Number = 20;

                        int Number = 30;                  

                        }

   5. Reserved words can't be used as identifiers (like a java keyword, such int or boolean).

   6. There is no limit for java indentifiers. But it's not recommanded to take morethan 15 lenght . (>15)

   7. all predefined java class names & interface name we can use as indetifiers. Eventhough it is legel but it is not recommanded.

            

Datatypes in Java 

Array In Java