Create Number counter in an Applet using Thread Example
- /*
- Create Number counter in an Applet using Thread Example
- This Java example shows how to create number counter using Java Thread and
- Applet classes.
- */
- import java.applet.Applet;
- import java.awt.Dimension;
- import java.awt.Font;
- import java.awt.FontMetrics;
- import java.awt.Graphics;
- /*
- <applet code = "UsingRepaintAndThreadExample" width = 500 height = 300>
- </applet>
- */
- /*
- Using paint() method we can draw strings, shapes or images.
- But when applets that use threads commonly need to update the display
- (ex. Animation or simulation).
- You cannot invoke the paint method directly to update the display.
- The reason is that the JVM schedules a number of important tasks. Updating
- the dispaly is one of these. The JVM decides when the screen can be updated.
- Therefore, your applet must invoke the repaint() method to request
- an update of the applet display. When the JVM determines that it is
- appropriate to perform this work, it calls the update method.
- The default implementation of the update() method clears the applet
- display with the background color and then invokes the paint() method.
- */
- public class UsingRepaintAndThreadExample extends Applet implements Runnable{
- int counter;
- Thread t;
- public void init(){
- counter = 0;
- t = new Thread(this);
- t.start();
- }
- public void run(){
- try{
- while(true){
- repaint();
- Thread.sleep(1000);
- ++counter;
- }
- }
- catch(Exception e){
- }
- }
- public void paint(Graphics g){
- g.setFont(new Font("Serif",Font.BOLD,30));
- FontMetrics fm = g.getFontMetrics();
- String s = "" + counter;
- Dimension d = getSize();
- int x = d.width/2 - fm.stringWidth(s)/2;
- int y = d.height/2;
- g.drawString(s,x,y);
- }
- }
