Overridden Method Demo in Java.

OverriddenMethod.java

/*
 * OverriddenMethod Demo.
 *
 * Method overriding. In a class hierarchy when superclass and subclass have a method with the same name and same signature than the method in subclass then is set to be overriden method.
 * It is the way of representing polymorphism.
 * A superclass reference can refer to its subclass object, but a subclass reference cannot refer to superclass object.
 */

class A {
  void display() {
  System.out.println("From class A");
  }
}

class B extends A { // Subclass of class A.
  void display() { // Overridden method.
  System.out.println("From class B");
  }
}

class C {
  void display() { // Normal method.
  System.out.println("From class C");
  }
}

class OverriddenMethod {
  public static void main(String args[]) {
  A a1 = new A();
  B b1 = new B();
  C c1 = new C();
  a1.display();
  b1.display();
  c1.display();

  A ref = b1;   // Refers to the object of class B.
  ref.display();   // Invokes display from class B.
  ref = a1;  // Refers to the object of class A.
  ref.display();   // Invokes display from class A.

  // ref = c1;  // Error.
  }
}