static public void main(String args[])
{
    Rectangle r = new Rectangle();
    Shape s;

    r.setPosition(1, 2);
    r.setDimensions(50, 50);
    s = r;
    s.setPosition(10, 20);
    System.out.println(r);
    System.out.println(s);
    r = (Rectangle)s;
}