AnimalTest.java Questions

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Program listing

// ARRAYS, INHERITANCE AND POLYMORPHISM TUTORIAL
// Copyright (C) 1998-2016 Davin Pearson
// Website: http://davin.50webs.com/java-tutorials

class AnimalTest
{
   private static void chatter(Animal[] a)
   {
      for (int i=0; i<a.length; i++)
      {
         a[i].talk();
      }
   }

   /*
    *
    * The main method is the point of entry into the program...
    *
    */
   public static void main(String[] args)
   {
      Animal[] farm = { new Dog(), new Cow(), new Kiwi() };

      Animal[] ark = { new Dog(), new Dog(), new Cow(), new Cow(),
                       new Kiwi(), new Kiwi() };

      Cow[] herd    = { new Cow(), new Cow(), new Cow() };

      chatter(farm);

      chatter(ark);

      chatter(herd);
   }
}

class Animal
{
   public boolean hasWings()
   {
      return false;
   }

   public boolean canFly()
   {
      return false;
   }

   public void talk()
   {
   }
}

class Dog extends Animal
{
   public void talk()
   {
      System.out.println("Woof woof!");
   }
}

// QUESTIONS:
//
// (1) Write the class Cow which extends class Animal.  Override all
// necessary methods.
//
// HINT: Look at how class Dog inherits from class Animal and
// follow the pattern.
// 
// (2) Write the class Bird which extends class Animal.  Override all
// necessary methods.
//
// (3) Write the class Kiwi which extends class Bird.  Override all
// necessary methods.
// 
// (4) Run the AnimalTest class to make sure that all the methods
// work correctly.
//
// (5) Rewrite the chatter method so that it never calls the
// talk methods and instead uses a series of "if" statements
// and the "instanceof" operator to test the run-time type
// of each object in the array "a".
//