Tank.java

/**
 * This class is the parent for
 * the Panzer and Alien classes.
 */
public abstract class Tank {

    /**
     * The unique attribute of each tank.
     */
    public int health;

    /**
     * Class constructor that assigns health.
     */
    protected Tank(int health) {
        this.health = health;
    }

    /**
     * Reduces the health of a tank by five points.
     * 
     * @see PlayerActions.shootBullet()
     */
    public final void decreaseHealthByFive() {
        this.health -= 5;
    }

    /**
     * Reduces the health of a tank to zero points.
     * 
     * @see PlayerActions.activateAtomicBomb()
     */
    public final void decreaseHealthToZero() {
        this.health = 0;
    }

    /**
     * Returns the health integer as a String with
     * at least a width of 2 (padded).
     */
    public final String getPaddedHealth() {
        // % - begin format specifier
        // 0 - variable 'salud' at index 0
        // 2 - width of two (with padding, e.g., 00)
        // d - to integer conversion
        return String.format("%02d", health);
    }
}

/**
 * A children class of Tank
 * whose initial health is 10.
 */
final class PanzerTank extends Tank {

    /**
     * Class constructor that calls the parent class.
     */
    public PanzerTank() {
        super(10);
    }

    /**
     * Formats the health info for
     * the String representation
     * 
     * @return A String with type and health
     */
    public String toString() {
        // % - begin format specifier
        // s - to string conversion
        return String.format("PT-%s", super.getPaddedHealth());
    }
}

/**
 * A children class of Tank
 * whose initial health is 20.
 */
final class AlienTank extends Tank {

    /**
     * Class constructor that calls the parent class.
     */
    public AlienTank() {
        super(20);
    }

    /**
     * Formats the health info into the String representation
     * 
     * @return A String with type and health
     */
    public String toString() {
        // % - begin format specifier
        // s - to string conversion
        return String.format("AT-%s", super.getPaddedHealth());
    }
}