/* * Copyright (c) 2000 David Flanagan.  All rights reserved. * This code is from the book Java Examples in a Nutshell, 2nd Edition. * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied. * You may study, use, and modify it for any non-commercial purpose. * You may distribute it non-commercially as long as you retain this notice. * For a commercial use license, or to purchase the book (recommended), * visit http://www.davidflanagan.com/javaexamples2. */package com.davidflanagan.examples.applet;import java.applet.*;         // Don't forget this import statement!import java.awt.*;            // Or this one for the graphics!import java.util.Date;        // To obtain the current timeimport java.text.DateFormat;  // For displaying the time/**  * This applet displays the time, and updates it every second  **/public class Clock extends Applet implements Runnable {    Label time;               // A component to display the time in    DateFormat timeFormat;    // This object converts the time to a string    Thread timer;             // The thread that updates the time    volatile boolean running; // A flag used to stop the thread    /**     * The init method is called when the browser first starts the applet.     * It sets up the Label component and obtains a DateFormat object     **/    public void init() {	time = new Label();	time.setFont(new Font("helvetica", Font.BOLD, 12));	time.setAlignment(Label.CENTER);	setLayout(new BorderLayout());	add(time, BorderLayout.CENTER);	timeFormat = DateFormat.getTimeInstance(DateFormat.MEDIUM);    }    /**     * This browser calls this method to tell the applet to start running.     * Here, we create and start a thread that will update the time each     * second.  Note that we take care never to have more than one thread     **/    public void start() {	running = true;                // Set the flag 	if (timer == null) {           // If we don't already have a thread	    timer = new Thread(this);  // Then create one	    timer.start();             // And start it running	}    }    /**     * This method implements Runnable.  It is the body of the thread.  Once     * a second, it updates the text of the Label to display the current time     **/    public void run() {	while(running) {     // Loop until we're stopped	    // Get current time, convert to a String, and display in the Label	    time.setText(timeFormat.format(new Date()));  	    // Now wait 1000 milliseconds	    try { Thread.sleep(1000); }	    catch (InterruptedException e) {}	}	// If the thread exits, set it to null so we can create a new one	// if start() is called again.	timer = null;    }    /**     * The browser calls this method to tell the applet that it is not visible     * and should not run.  It sets a flag that tells the run() method to exit     **/    public void stop() { running = false; }     /**     * Returns information about the applet for display by the applet viewer     **/    public String getAppletInfo() {	return "Clock applet Copyright (c) 2000 by David Flanagan";    }}