BouncingBall.java

/** 
 * Lab 2: BouncingBall.java
 * Extends SmartEllipse, adding the ability to "bounce."
 */
public class BouncingBall extends SmartEllipse implements Mover {
    private int _changeX, _changeY; // attributes
    private int _moveLen = 5;
    private javax.swing.JPanel _panel; // peer object (and container)
    private javax.swing.Timer _timer;

    public BouncingBall (java.awt.Color aColor, int anInterval, 
                         javax.swing.JPanel aPanel){
        // Instantiate the JPanel
        super(aColor);
        // Initialize the change in each direction per timer tick
        _changeX = _moveLen;
        _changeY = _moveLen;
        // Save the peer which is the panel on which the block appears
        _panel = aPanel;
        // Instantiate the timer for the block
        _timer = new MoveTimer(anInterval, this);
        // Start the timer
        _timer.start();
}

    public void move() {
        int nextX = (int)this.getX() + _changeX;
        int nextY = (int)this.getY() +  _changeY;
        if (nextX <= this.getMinBoundX()) {
            _changeX *= -1;
            nextX = this.getMinBoundX();
        }
        else if (nextX >= this.getMaxBoundX()) {
            _changeX *= -1;
            nextX = this.getMaxBoundX();
        }
        if (nextY <= this.getMinBoundY()) {
            _changeY *= -1;
        nextY  = this.getMinBoundY();
        }
        else if (nextY > this.getMaxBoundY()){
            _changeY *= -1;
            nextY = this.getMaxBoundY();
        }
        this.setLocation(nextX, nextY);
        _panel.repaint();
    }
    public int getMinBoundX() {
        return (int) _panel.getX();
    }
    public int getMinBoundY() {
        return (int) _panel.getY();
    }
    public int getMaxBoundX() {
        return (int) (_panel.getX() + _panel.getWidth() - this.getWidth());
    }
    public int getMaxBoundY() {
        return (int) (_panel.getY() + _panel.getHeight() 
        - this.getHeight());
    }
    public void setMoveLength(int value)
    {
        _moveLen = value;
        if(_changeX >=0) 
            _changeX = value;
        else
            _changeX = value * -1;
        if(_changeY >=0)
            _changeY = value;
        else
            _changeY = value * -1;
   }
   public java.awt.Color getColor()
   {
       return super.getFillColor();
   }
}