// An example to illustrate polymorphism.
public class Shapes extends Applet
{
    private Shape shape;
    private Circle circle;
    private Rectangle rectangle;

    public void init ()
    {
        shape = new Shape (Color.blue, 50, 100);
        circle = new Circle (Color.red,100, 100, 30);
        rectangle = new Rectangle (Color.green, 200, 100, 60, 40);
    } // method init

    public void paint (Graphics g)
    {
        shape.drawShape (g);
        shape = circle;
        shape.drawShape (g);
        shape = rectangle;
        shape.drawShape (g);
    } // method paint
} // public class Shapes extends Applet

class Shape
{
    protected Color color;
    protected int x, y;

    Shape (Color c, int xVal, int yVal)
    {
        color = c;
        x = xVal;
        y = yVal;
    } // method shape

    public void drawShape (Graphics g)
    {
        g.setColor (color);
        g.drawString ("Shape", x, y);
    } // method drawShape
} // class Shape

class Circle extends Shape
{
    private int radius;

    Circle (Color c, int x, int y, int r)
    {
        super (c, x, y);
        radius = r;
    } // method Circle

    public void drawShape (Graphics g)
    {
        g.setColor (color);
        g.fillOval (x, y, 2*radius, 2*radius);
    } // method drawShape
} // class Circle

class Rectangle extends Shape
{
    private int width, height;

    Rectangle (Color c, int x, int y, int w, int h)
    {
        super (c, x, y);
        width = w;
        height = h;
    } // method Rectangle

    public void drawShape (Graphics g)
    {
        g.setColor (color);
        g.fillRect (x, y, width, height);
    } // method drawShape
} // class Rectangle