File: Class.java

/* <applet code=Clock.class height=110 width=200>
   </applet>
 */

import java.awt.*;
import java.util.Date;


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

// Instance variables
    Thread aThread; // Handle for Thread object
    Date date;      // Handle for Date object
    Frame frame;    // Handle for window (Frame object)
    Graphics graphics;  // Handle for drawing graphics

// A class variable to distinguish between Applet
// and the standalone version
    private static boolean isApplet = true;

// Constructor for Clock object, called whenever a
// new object is created

public Clock() {
   if (isApplet) { // Standalone version uses MakeWindow()
       Panel p = new Panel();
       p.add(new Button("Start"));
       p.add(new Button("Stop"));
       add("North", p);
       }
}

// init() is called by the appletviewer when applet is
// first loaded; gets the Applet's Panel's Graphics

public void init() {
    graphics = getGraphics();
    date = new Date();
    }

// paint() is called from run() and by appletviewer

public void paint(Graphics g) {
    g.clearRect(25,25,150,50);
    g.drawString(date.toString(), 25, 60);
    }

// start() is called when applet's panel becomes visible

public void start() {
    if (aThread == null) {
        aThread = new Thread(this);
        aThread.start();
        }
    }

// stop() is called when the appletviewer changes pages

public void stop() {
    if (aThread != null) {
        aThread.stop();
        aThread = null;
        }
    }

// run() gets called when Thread is started, stops
// via stop()

public void run() {
    while (true) {
        date = new Date();
        paint(graphics);
        try {Thread.sleep(1000); }
        catch (InterruptedException e) {};
        }
    }

// action() is called when Stop button is clicked 
// within the Applet Panel

public boolean action(Event e, Object arg) {
    if (e.target instanceof Button) {
        if (((String)arg).equals("Stop")) stop();
        else start();
        return true;
        }
    return false;
}

// main() is called only when started standalone

public static void main(String args[]) {
    isApplet = false;
    Clock clock = new Clock();
    clock.frame = new MakeWindow("Clock Window", clock);
    clock.graphics = clock.frame.getGraphics();
    clock.start();
    }
}

// A second helper class; could be in a separate file
class MakeWindow extends Frame {

// Instance variable
Clock clock;

// Constructor for new MakeWindow object

public MakeWindow(String name, Clock applet) {
    super(name);
    clock = applet;
    Panel p = new Panel();
    p.add(new Button("Start"));
    p.add(new Button("Stop"));
    add("North", p);
    resize(200, 110);
    show();
    }

public boolean handleEvent(Event e) {
    if (e.id == Event.ACTION_EVENT) {
        if (e.target instanceof Button) {
            String s = ((Button)e.target).getLabel();
            if (s.equals("Stop")) clock.stop();
            else clock.start();
        }
    }
    else
    if (e.id == Event.WINDOW_DESTROY) {
        this.hide();
        System.exit(0);
        }
    else
        super.handleEvent(e);
    return true;
    }