Java Tutorial/Thread/ScheduledThreadPoolExecutor

Animation with ScheduledThreadPoolExecutor

   <source lang="java">

import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.Shape; import java.awt.geom.Ellipse2D; import java.util.concurrent.ScheduledThreadPoolExecutor; import java.util.concurrent.TimeUnit; import javax.swing.JComponent; import javax.swing.JFrame; public class BallRoom {

 public static void main(String[] a){
   JFrame f = new JFrame();
   f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   f.setSize(200, 300);
   PaintSurface canvas = new PaintSurface();
   ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(3);
   executor.scheduleAtFixedRate(canvas, 0L, 100L, TimeUnit.MILLISECONDS);
   
   f.getContentPane().add(canvas);
   f.setVisible(true);
   
 }

} class PaintSurface extends JComponent implements Runnable{

 int i = 0;
 public void run() {
   repaint();
 }
 public void paint(Graphics g) {
   Graphics2D g2 = (Graphics2D) g;
   g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
   Shape ball = new Ellipse2D.Float(i++, i++, 5, 5);
   g2.setColor(Color.RED);
   g2.fill(ball);
 }

}</source>

JDK1.5 provides a mechanism to create a pool a scheduled task

   <source lang="java">

import java.util.concurrent.ScheduledThreadPoolExecutor; import java.util.concurrent.TimeUnit; public class Main{

 public static void main(String args[]) {
   ScheduledThreadPoolExecutor stpe = new ScheduledThreadPoolExecutor(5);
   
   stpe.scheduleAtFixedRate(new Job1(), 0, 5, TimeUnit.SECONDS);
   stpe.scheduleAtFixedRate(new Job2(), 1, 2, TimeUnit.SECONDS);
 }

} class Job1 implements Runnable {

 public void run() {
   System.out.println("Job 1");
 }

} class Job2 implements Runnable {

 public void run() {
     for(int i=0;i<99;i++){
       System.out.println(i);
     }
 }

}</source>

Return a value from a thread.

   <source lang="java">

import java.util.concurrent.Callable; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; import java.util.concurrent.Future; public class Main {

 public static void main(String args[]) throws Exception{
   ExecutorService es = Executors.newFixedThreadPool(3);
   Future<Double> f = es.submit(new Task1());
   Future<Integer> f2 = es.submit(new Task2());
   System.out.println(f.get());
   System.out.println(f2.get());
   es.shutdown();
 }

} class Task1 implements Callable<Double> {

 Task1() {
 }
 public Double call() {
   return 0.0;
 }

} class Task2 implements Callable<Integer> {

 Task2() {
 }
 public Integer call() {
   return 1;
 }

}</source>