Question

How to access print method of class A in main method? Difference between objects a and b created in main method?

  abstract class A {
        void print() {
            System.out.println("A");
        }
    }

    class B extends A {
        void print() {
        System.out.println("B");
        }
    }



    public class test {
        public static void main(String[] args) {
            B b = new B();
            A a = new B();
            b.print();
            a.print();
        }

    }

Answer 1

In both cases, overriden print() in class B will be invoked.

Case 1: B b = new B();

this case is straightforward. you create B object with B reference.

Case2: A a = new B();

Here, you are creating B object with A reference. this is called polymorphicaly creating an object or coding to an interface. as you have overridden print() in class B, during run-time overloaded method of class B will be invoked.

Other option:

create a method in class B which would invoke print method of class A using super keyword.

   class B extends A {
        public void someOtherMethod(){
            super.print();
         }
    }
   from main:
      B  b = new B();
      b.someOthermethod();