CMPUT 114 - INTRODUCTION TO COMPUTING SCIENCE

Sample Code

Last updated on: Sunday January 21st 2001

/*

	C. Jones, Winter 2001

	Very simple example of polymorphism - declared type of anAnimal is Animal, but

	anAnimal can be bound to an instance of its subclass, Dog.

	Also, the displayMe() method is overridden in the subclass.

	Note: which version of displayMe() is invoked after anAnimal

	has been bound to an instance of the Dog class? 

*/





public class Example2 {



	public static void main(String args[]) {

		Animal anAnimal = new Animal();

		anAnimal.displayMe();

		anAnimal = new Dog();

		anAnimal.displayMe();

	}

}



public class Animal {

	protected  String name;

	protected  int legs;

	

	public Animal(){

		this.name = "Animal";

		this.legs = 0;

	}

	

	public Animal(String name, int legs){

		this.name = name;

		this.legs = legs;

	}

	

	public void displayMe(){

	// print my details on screen

		System.out.println(this.name + ", " + this.legs);

	}

}



public class Dog extends Animal {

	private static String noise = "Woof!";

	

	public Dog(){

		super("Dog", 4);

	}

	

	public void displayMe(){

	// print my details on screen

		System.out.println(this.name + ", " + this.legs + ", " + Dog.noise);

	}

}

		Department of Computing Science University of Alberta