public class Bird { private static final int GRAVITY = 20; private static final int JUMP_SPEED = 7; private final Rectangle _rect; private double _speed; public Bird(Manager man) { _rect = new Rectangle(20, 20, 20, 20, "cyan", true); man.addDrawable(_rect); } public void update(double elapsed) { _speed += GRAVITY * elapsed * 1e-3d; _rect.setPos(_rect.getX(), _rect.getY() + _speed); } public void jump() { _speed = -JUMP_SPEED; } public Rectangle getRect() { return _rect; } }