// ButtonFun Demo

import java.applet.Applet;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
   This applet lets the user move a rectangle by clicking
   on buttons labeled "Left", "Right", "Up", and "Down".
*/
public class ButtonFun extends Applet
{  
   private Rectangle box;
   private static final int BOX_X = 100;
   private static final int BOX_Y = 100;
   private static final int BOX_WIDTH = 20;
   private static final int BOX_HEIGHT = 30;
   
   public ButtonFun()
   {  
      // the rectangle that the paint method draws
      box = new Rectangle(BOX_X, BOX_Y, BOX_WIDTH, BOX_HEIGHT);

      // the panel for holding the user interface components
      JPanel panel = new JPanel();

      panel.add(makeButton("Left", -BOX_WIDTH, 0));
      panel.add(makeButton("Right", BOX_WIDTH, 0));
      panel.add(makeButton("Up", 0, -BOX_HEIGHT));
      panel.add(makeButton("Down", 0, BOX_HEIGHT));

      // the frame for holding the component panel
      JFrame frame = new JFrame();
      frame.setContentPane(panel);
      frame.pack();
      frame.show();
   }

   public void paint(Graphics g)
   {  
      Graphics2D g2 = (Graphics2D)g;
      g2.draw(box);
   }

   /**
      Makes a button that moves the box.
      @param label the label to show on the button
      @param dx the amount by which to move the box in x-direction
      when the button is clicked
      @param dy the amount by which to move the box in y-direction
      when the button is clicked
      @return the button
   */
   public JButton makeButton(String label, final int dx, final int dy)
   {
      JButton button = new JButton(label);

      class ButtonListener implements ActionListener
      {
         public void actionPerformed(ActionEvent event)
         {
            box.translate(dx, dy);
            repaint();
         }
      };

      ButtonListener listener = new ButtonListener();
      button.addActionListener(listener);
      return button;
   }

}