1  import java.awt.Graphics;

  2  import java.awt.Graphics2D;

  3  import java.awt.Rectangle;

  4  import javax.swing.JComponent;

  5  

  6  /**

  7     This component displays a rectangle that can be moved. 

  8  */

  9  public class RectangleComponent extends JComponent

 10  {  

 11     private static final int BOX_X = 100;

 12     private static final int BOX_Y = 100;

 13     private static final int BOX_WIDTH = 20;

 14     private static final int BOX_HEIGHT = 30;

 15  

 16     private Rectangle box;

 17  

 18     public RectangleComponent()

 19     {  

 20        // The rectangle that the paintComponent method draws 

 21        box = new Rectangle(BOX_X, BOX_Y, BOX_WIDTH, BOX_HEIGHT);         

 22     }

 23  

 24     public void paintComponent(Graphics g)

 25     {  

 26        Graphics2D g2 = (Graphics2D) g;

 27        g2.draw(box);

 28     }

 29  

 30     /**

 31        Moves the rectangle by a given amount. 

 32        @param dx the amount to move in the x-direction 

 33        @param dy the amount to move in the y-direction 

 34     */

 35     public void moveRectangleBy(int dx, int dy)

 36     {

 37        box.translate(dx, dy);

 38        repaint();      

 39     }

 40  }