Animal.java
              package pack1;
              
              public abstract class Animal
              
              {
              protected String name;
              protected String sound;
              
              public Animal(String name, String sound)
              
              {
              this.name = name;
              this.sound = sound;
              }
              
              public abstract void makeSound();
              }
              Cat.java
              package pack1;
              
              public class Cat extends Animal {
              
              public Cat(String name) {
              super(name, "Meow!");
              }
              
              @Override
              public void makeSound() {
              System.out.println(name + " says: " + sound);
              }
              }
              Dog.java
              package pack1;
              
              public class Dog extends Animal {
              
              public Dog(String name)
              {
              super(name, "Woof!");
              }
              
              @Override
              public void makeSound() {
              System.out.println(name + " says: " + sound);
              }
              }
              
              Bird.java
              package pack1;
              
              public class Bird extends Animal {
              
              public Bird(String name) {
              super(name, "Chirp!");
              }
              
              @Override
              public void makeSound() {
              System.out.println(name + " says: " + sound);
              }
              }
              Main.java
              package pack1;
              
              public class Main {
              
              public static void main(String[] args) {
              Dog dog = new Dog("Rex");
              dog.makeSound();
              
              Cat cat = new Cat("Kitty");
              cat.makeSound();
              
              Bird bird = new Bird("Tweety");
              bird.makeSound();
              }
              }