// JDK 1.1

import java.awt.*;
import java.awt.event.*;

public class BouncingBall3a extends java.applet.Applet implements Runnable {

  protected BouncingBallCanvas canvas; 
  protected Panel controlPanel; 
  
  protected static final int START = 1; 
  protected static final int STOP = 2;
    
  Thread bouncingThread;
  int delay = 400;    

  protected class StartStopButtonHandler implements ActionListener {
  
    private int cmd = 0; 
    
    public StartStopButtonHandler(int cmd) {
      this.cmd = cmd;     
    }
     
    public void actionPerformed(ActionEvent event) { 
      switch (cmd) {
      case START:
        start(); 
        break; 
      case STOP:
        stop();
        break; 
      }          
    }
  }
  
  protected class ColorChoiceHandler implements ItemListener {
    public void itemStateChanged(ItemEvent event)  {    
      Choice choice = (Choice) event.getSource();  
      if (choice != null) {
        if ("red".equals(event.getItem())) {
          canvas.setColor(Color.red); 
        } else if ("green".equals(event.getItem())) {
          canvas.setColor(Color.green); 
        } else if ("blue".equals(event.getItem())) {
          canvas.setColor(Color.blue); 
        } 
      }
    }
  }
  
  public BouncingBall3a() {
    setLayout(new BorderLayout());
    canvas = new BouncingBallCanvas(); 
    add("Center", canvas); 

    controlPanel = new Panel(); 
    controlPanel.setLayout(new GridLayout(1,0));     
    Button startButton = new Button("start");
    controlPanel.add(startButton);
    Button stopButton = new Button("stop");
    controlPanel.add(stopButton);
    Choice choice = new Choice();
    choice.addItem("red");
    choice.addItem("green");
    choice.addItem("blue");
    controlPanel.add(choice); 
    add("South", controlPanel); 

    startButton.addActionListener(new StartStopButtonHandler(START)); 
    stopButton.addActionListener(new StartStopButtonHandler(STOP)); 

    choice.addItemListener(new ColorChoiceHandler()); 
  }

  public void init() {
    String att = getParameter("delay");
    if (att != null) 
      delay = Integer.parseInt(att);
    doLayout();
    canvas.init();
  }

  public void start() {
    if (bouncingThread == null) {
      bouncingThread = new Thread(this);
      bouncingThread.start();
    }
  }
  
  public void stop() {
    if (bouncingThread != null) {
      bouncingThread = null; 
    }
  }
  
  public void run() {
    while (Thread.currentThread() == bouncingThread) {
      try { 
        Thread.currentThread().sleep(delay); 
      }                                            
      catch (InterruptedException e){}
      canvas.repaint();
    }
  }
      
}