How to lock in one thread and wait until lock will be released in another thread

I just want wait in main thread until some event in run. How can I do it using java.util.concurency classes? Thanks!

P.S. Does my question realy explained bad o correctness check is shit? I mean this message "Oops! Your question couldn't be submitted because:

Your post does not have much context to explain the code sections; please explain your scenario more clearly."?

public class LockingTest {
    private Lock initLock = new ReentrantLock();

    @Test
    public void waiting(){
        initLock.lock();
        final Condition condition = initLock.newCondition();
        long t1= System.currentTimeMillis();
        Thread th = new Thread(new Runnable(){
            @Override public void run() {

                try {
                    Thread.currentThread().sleep(2000);
                } catch (Interrupted开发者_StackOverflowException e) {}
                initLock.unlock();
           }
        });
        th.start();

        try {
            condition.await(3000, TimeUnit.MILLISECONDS);
        } catch (InterruptedException e) {}

        long t2= System.currentTimeMillis();
        System.out.println(t2-t1);
    }
}

you can use CountDownLatch( http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/CountDownLatch.html ).

 1. init countdownlatch with count value 1
 2. start another thread (Thread A )
 3. call await() in main thread
 4. call countdown() in Thread A