Aliens!

The following is some code designed by J. Hacker for a video game. There is an Alien class to represent a monster and an AlienPack class that represents a band of aliens and how much damage they can inflict:

public class Alien { public static final int SNAKE_ALIEN = 0; public static final int OGRE_ALIEN = 1; public static final int MARSHMALLOW_MAN_ALIEN = 2; public int type; // Stores one of the three above types public int health; // 0=dead, 100=full strength public String name; public Alien(int type, int health, String name) { this.type = type; this.health = health; this.name = name; } } // end class Alien

public class AlienPack { private Alien[] aliens; public AlienPack(int numAliens) { aliens = new Alien[numAliens]; } public void addAlien(Alien newAlien, int index) { aliens[index] = newAlien; } public Alien[] getAliens() { return aliens; } public int calculateDamage() { int damage = 0; for (int i = 0; i < aliens.length; i++) { if (aliens[i].type == Alien.SNAKE_ALIEN) { damage += 10;// Snake does 10 damage } else { if (aliens[i].type == Alien.OGRE_ALIEN) { damage += 6;// Ogre does 6 damage } else { if (aliens[i].type == Alien.MARSHMALLOW_MAN_ALIEN) { damage += 1; // Marshmallow Man does 1 damage } } } } return damage; } } // end class AlienPack

This code is not very object oriented and does not support information hiding in the Alien class.

Rewrite the code so that inheritance is used to represent the different types of aliens instead of the type parameter. This should result in deletion of the type parameter.

Also rewrite the Alien class to hide the instance variables and create a getDamage method for each derived class that returns the amount of damage the alien inflicts.

Finally, rewrite the calculateDamage method to use getDamage and write a main method that tests the code.