Java : Interfaces in Java

package udemy;

public interface InterfaceForClass {

int min_bal=100;

public abstract void Credit();
public abstract void Debit();

}

package udemy;

public class ClassForInterface implements InterfaceForClass{

public void Credit() {

System.out.println("From Credit Method");

}

public void Debit() {

System.out.println("From Debit Method");

}

public void MethodNotinInterface() {

System.out.println("this method does not belong to interface");

}

public static void main(String []args) {

ClassForInterface c1=new ClassForInterface();

c1.Credit();

c1.Debit();

c1.MethodNotinInterface();

System.out.println("@@@@@@@@@@@@Separator@@@@@@@@@@@@@@@@@");

InterfaceForClass i=new ClassForInterface();

i.Credit();

i.Debit();

System.out.println(min_bal); //=>100

min_bal=min_bal+1; // THIS IS NOT POSSIBLE. VARIABLES IN INTERFACE ARE FINAL

i.MethodNotinInterface() //THIS METHOS WILL NOT POP UP

}

}

//Output:

From Credit Method
From Debit Method
this method does not belong to interface
@@@@@@@@@@@@Separator@@@@@@@@@@@@@@@@@@@@@@@

//Below Accessed from InterFace reference
From Credit Method
From Debit Method
100