/** Pet.java - example of polymorphism
 *  We're going to declare a variable pet of the Animal class.
 *  But 'pet' will assume different dynamic types depending on which
 *  constructor we use.
 */
public class Pet
{
  public static void main(String [] args)
  {
      Animal pet;

      System.out.printf("animal #1...\n");
      pet = new Bird();
      pet.feed();

      System.out.printf("\nanimal #2...\n");
      pet = new Fish();
      pet.feed();

      // Let's make a Penguin.  Even casting it as a Bird doesn't fool the
      // compiler.  It's still a Penguin!
      System.out.printf("\nanimal #3...\n");
      pet = new Penguin();
      pet = (Bird) pet;
      pet.feed();
  }
}