Question

CODE:1

class Ajay {
    private void display() {
        System.out.println("Ajay");
    }
    public static void main(String ...strings ){
        Ajay r=new Ravi();
        r.display();
    }
}

class Ravi extends Ajay{
    public void display() {
        System.out.println("ravi");
    }
}

CODE:2

class Ravi {
    private void display() {
        System.out.println("ravi");
        }
    }

public class Ajay extends Ravi{
    public void display() {
        System.out.println("ajay");
    }
    public static void main(String ...strings ){
    Ravi r=new Ajay();
        r.display();
    }
}

I have a doubt in the above two codes.
CODE 1 executes without any error while CODE 2 throws an error like The method is not visible.
What is the reason for this error??

Answer 1

In your second example you try to call a method display() on a variable of type Ravi. Ravi has no method display() that’s accessible from this location (i.e. inside Ajay).

In your first example, however you call the private display() method of Ajay from within Ajay. Note that calling private methods does not use runtime polymorphism! The exact code to be called is decided at compile-time!