package polymorphism; public class TestPolymorphism { public static void main(String[] args) { Animal animal1 = new Animal(); System.out.println(animal1.shout()); // Don't Know! Animal animal2 = new Dog(); // Reference variable type => Animal // Object referred to => Dog // Dog's bark method is called. System.out.println(animal2.shout()); // BOW BOW // Even though dog has a method run,it cannot be // invoked using super class reference variable // animal2.run();//COMPILE ERROR } }