Threads waiting the same event

Question

hi all,
i have two thread waiting an event
and another who notify them
//the class event
public final class Event {
* variable used to store the notification if it takes place
* before being expected
private boolean status = false;
public final synchronized void waitForNotification() {
while (status == false ) {
try {
wait();
catch (InterruptedException e) {
status = false ;
// notify all waits on this event
public final synchronized void wakeUp() {
status = true;
notifyAll();
// the class TestThread implements a thread that have an event waiting for a notification
public class TestThread extends Thread{
private Event event;
public TestThread( Event e){
event=e;
public void run(){
for (int i = 1; i < 4; i += 1) {
try {
Thread.sleep(2);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
e.waitForNotification();
// the class TestThread2 implements a thread that have an event waiting for a notification
public class TestThread2 extends Thread{
private Event event;
public TestThread( Event e){
event=e;
public void run(){
for (int i = 1; i < 4; i += 1) {
e.wakeUp();
//the class main
public class test {
* @param args
public static void main(String[] args) {
// TODO Auto-generated method stub
Event e = new event();
TestThread th1 = new TestThreadConsumer(e);
TestThread th2 = new TestThread(e);
TestThread2 th= new TestThread2(e);
th1.start();
th2.start();
th3.start();
1st case
the problem is that the notification could not be seen to the tow threads
because if the tow are waiting the notification
and the other thread send notification
one of the tow see the notificztion and wake up and set the flag status to false so the other one could not ever wake up
2d case
the notification of the second thread could be done in the second itiration or in the other ones
please could u answer and help me
thank you

Answer 1

nabila.abdessaied wrote:
i just wanna to have tow thread waiting a notification from another
and when another send the notification
they could go out from waiting and do their jobHi.
Below is an example of how you could do this. It is taken from http://www.javaconcurrencyinpractice.com/listings.html (5.11 Using CountDownLatch for starting and stopping threads in timing tests) .
The idea is simple:
(1) main thread starts nThreads, but all of them, once started, are "suspended" in startGate.await();
(2) when all threads are started, main thread calls startGate.countDown(); and all those waiting threads "are off" at once.
I'm not sure that you need 'endGate' though (but I thought that it is not that good to cut somebody's else example...)
* TestHarness
* <p/>
* Using CountDownLatch for starting and stopping threads in timing tests
* @author Brian Goetz and Tim Peierls
public class TestHarness {
    public long timeTasks(int nThreads, final Runnable task)
            throws InterruptedException {
        final CountDownLatch startGate = new CountDownLatch(1);
        final CountDownLatch endGate = new CountDownLatch(nThreads);
        for (int i = 0; i < nThreads; i++) {
            Thread t = new Thread() {
                public void run() {
                    try {
                        startGate.await();
                        try {
                            task.run();
                        } finally {
                            endGate.countDown();
                    } catch (InterruptedException ignored) {
            t.start();
        long start = System.nanoTime();
        startGate.countDown();
        endGate.await();
        long end = System.nanoTime();
        return end - start;
}Seems this is what you were looking for (if I understood you right).