Chapter 9

CREATING A DIGITAL CLOCK IN JAVA In this little short tutorial i 'll teach you how to create a digital clock in Java applet programming.This tutorial assumes that you have some knowledge of Java applet or console programming so lets start ... First We'll need to import all those java class libraries we'll need later. import java.awt.*; import java.awt.Graphics.*; import java.util.Date; import java.applet.Applet; These are the libraries and classes we'll need the first one java.awt.* imports all the abstract window toolkit classes e.g awt.Font,awt.Color etc....The Second one awt.Graphics.*, will include or import classes which are necessary for painting and repainting ,import java.util.Date will include the class for Date and the last but not the least will help us in building the applet. ok now lets start out class: public class digitalClock extends Applet implements Runnable /* I have included Runnable because we are gonna work with Threads that you will see soon*/ Thread run; Font f=new Font("ArialBlack",Font.BOLD,20); Date now; Here i have created an instance variable run of Thread class the next instance variable f will be used to hold the objects for Font and and now is the variable responsible for holding the Date object. so till now we have: import java.awt.Graphics.*; import java.awt.*; import java.applet.Applet; import java.util.Date; public class digitalClock extends Applet implements Runnable{ Thread run; Font f=new Font("ArialBlack",Font.BOLD,20); Date now; Now lets forward this by adding a start and stop methods which will be resonsible for starting and stoping of applet. public void start(){ if(run==null){ /*Checks if the Thread object run is already null */ run=new Thread(this); / *Creates a new thread for the current object*/ run.start(); //Starts the Thread } } public void stop(){ if (run!=null){ //Checks if the Thread is already has already stopped or not run.stop(); //Stops the Thread execution run=null; //Frees the run } } Next we will add the run method which is very important public void run(){ while (true){ /*Infinite Loop*/ now=new Date(); /*Initializes now with the current date*/ repaint(); /*repaints the screen to update the changes*/ try{ /*Exception*/ Thread.sleep(1000); /*Sleep the thread for 1 second 1000 miliseconds so 1000/1000=1 */ }catch(InterruptedException ie){} } } The run method will repaint the screen after 1 second and now the last method : public void paint(Graphics g){ g.setFont(f); //sets the font g.setColor(Color.red); //sets the color g.drawString(now.toString(),10,25); /*draws the string =>g.drawString(String,x,y).*/ } } the paint method will at last show the time in the applet now.toString() will change it into String format instead of Date. and now the full source code : /********************Code Starts Here*******************/ import java.awt.Graphics.*; import java.awt.*; import java.applet.Applet; import java.util.Date; public class myApplet extends Applet implements Runnable{ Thread run; Font f=new Font("ArialBlack",Font.BOLD,20); Date now; public void start(){ if(run==null){ run=new Thread(this); run.start(); } } public void stop(){ if (run!=null){ run.stop(); run=null; } } public void run(){ while (true){ now=new Date(); repaint(); try{ Thread.sleep(1000); }catch(InterruptedException ie){} } } public void paint(Graphics g){ g.setFont(f); g.setColor(Color.red); g.drawString(now.toString(),10,25); } } /********************************Code Ends Here*******************************/ Also if you dont know how to compile and run the code here are some hints: First create an html page for it and include the tag: But if you are a dumbass then i have the full html code: Chapter 9

Save the above html code as "digitalClock.html" The code has been compiled on JDK 1.3 and works 100%.So there are no errors in the code but the article may have some grammatical or spelling mistakes so forgive me for that. Compiled as javac digitalClock.java appletviewer digitalClock.html I hope you will like this article Its not for beginners though . Written for Ebcvg E-zine Copyright(C) NrAziz cyberghost4@hotmail.com www.nraziz.tk (For updates and more tutorials) 9:41 AM 11/28/02