/**
 * Class representing a generic loud toy. 
 * Exists only to serve as a superclass.
 */
public class LoudToy
{
    private int volume;

    public LoudToy(int volume)
    {
        this.volume = volume;
    }

    public void makeNoise()
    {
        // This should be overridden in subclasses.
        System.out.println("Generic noise.");
    }

    public int getVolume()
    {
        return volume;
    }

}


/**
 * A rechargable toy robot.
 */
public class ToyRobot extends LoudToy
{
    private int chargeLevel;

    public ToyRobot()
    {
        super(10);
        chargeLevel = 5;
    }

    public void makeNoise()
    {
        System.out.println("Beep Beep!");
    }

    public void recharge()
    {
        chargeLevel = 10;
        System.out.println("Charged up!");
    }

}



/**
 * A toy sheep that says "Baaa."
 */
public class ToySheep extends LoudToy
{

    public ToySheep()
    {
        super(3);
    }

    public void makeNoise()
    {
        System.out.println("Baaa.");
    }

}


/**
 *  Utility methods to help us play with toys.
 */
public class PlayUtils
{
    public static void playWithLoudToy(LoudToy toy)
    {
        System.out.println("This is a fun loud toy!");
        toy.makeNoise();
    }

    public static void playWithLoudToy(ToyRobot robot)
    {
        System.out.println("This is a fun robot!");
        robot.makeNoise();
    }

}


public class ToyDriver
{

    public static void main(String args[])
    {
        overloadedMethodExample();
    }

    public static void nonPolymorphism()
    {
        ToyRobot robot;
        robot = new ToyRobot();
        robot.makeNoise();
        robot.recharge();
    }

    public static void polymorphismAndDynamicBinding()
    {
        LoudToy toy;
        toy = new ToySheep();
        toy.makeNoise();
        toy = new ToyRobot();
        toy.makeNoise();
        // toy.recharge(); // Won't compile, even though toy contains a ToyRobot.
    }

    public static void castingExample()
    {
        LoudToy toy;
        toy = new ToyRobot();
        toy.makeNoise();

        // This cast is OK. toy does contain a ToyRobot.
        ToyRobot robot = (ToyRobot) toy;
        robot.recharge();
    }

    public static void badCastingExample()
    {
        LoudToy toy;
        toy = new ToySheep();
        toy.makeNoise();

        // Compiles, but will cause a run-time error.
        ToyRobot robot = (ToyRobot) toy;
        robot.recharge();
    }
    
    
    public static void overloadedMethodExample()
    {
        LoudToy toy;
        ToyRobot robot;
        
        robot = new ToyRobot();
        toy = robot;
        
        // The superclass version will be called...
        PlayUtils.playWithLoudToy(toy);
        
        // The subclass version will be called...
        PlayUtils.playWithLoudToy(robot);

        ToySheep sheep;
        sheep = new ToySheep();
        
        // The superclass version will be called, because
        // there is no method defined for this subclass.
        PlayUtils.playWithLoudToy(sheep);
        
    }

}