Using Final

class A{
    final void show(){
        System.out.println("This method cant override");
    }
}
class B extends A{
    /***********
     * This is an Error
        void show(){
            System.out.println("Error");
        }
     *********/
}
public class Main{
    public static void main(String args[]){
        A supob = new A();
        B subob = new B();
        supob.show();
    }
}