Re: Threads: wait and resume methods.

You'll need to do the notify in the same synchronized block as the wait.
What I mean is that in synchronized (this) { wait() } the synchronized
makes sure that thread has the monitor for 'this'... wait() can be read
as this.wait(). The notify should be executed on the same object as
'this' refers too in the wait. The synchronized of the notify should be
on the object the notify is invoked on which is the same object the wait
is invoked on which is the same object the synchronized is applied to. So:

class X {

    void waitOnMe() {
        synchronized(this) {
            wait();
        }
    }

    void goOn() {
        synchronized(this) {
            notify();
        }
    }
}

class Y {

    private X x = new X();

    void goOnFromY() {
        synchronized(x) {
            x.notify();
        }
    }

    void goOnInX() {
        x.goOn();
    }

}

Hope it helps,
Vincent