That is what we called as Virtual Method Invocation or Late Binding
Let us look at an example.
public interface Vegetarian{}
public class Animal{}
public class Deer extends Animal implements Vegetarian{}
Now, the Deer class is considered to be polymorphic since this has multiple inheritance. Following are true for the above example:
A Deer IS-A Animal
A Deer IS-A Vegetarian
A Deer IS-A Deer
A Deer IS-A Object
When we apply the reference variable facts to a Deer object reference, the following declarations are legal:
Deer d = new Deer();
Animal a = d;
Vegetarian v = d;
Object o = d
All the reference variables d,a,v,o refer to the same Deer object in the heap.
