Re: notify() and wait()

From:

Tom Anderson <twic@urchin.earth.li>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 10 Jan 2010 13:53:15 +0000

Message-ID:

<alpine.DEB.1.10.1001101351150.18392@urchin.earth.li>

On Sat, 9 Jan 2010, Patricia Shanahan wrote:

Tom Anderson wrote:

On Sat, 9 Jan 2010, Jack wrote:

I have two threads: thread1 and thread2 and use myObject for
synchronization.

Object myObject = new Object();

If thread1 calls myObject.notify() first, then thread2 calls
myObject.wait(). The wait() still blocks thread2, right?

In general, it is difficult to control the timing of notify() and wait
() call. How to prevent this situation.

I suspect that what you really want is a CountDownLatch:

http://java.sun.com/javase/6/docs/api/java/util/concurrent/CountDownLatch.html

Not necessarily.

Oh, absolutely - but it's what i suspect.

The original question could have been exactly the same if, for example,
the OP were trying to build a blocking queue from first principles. I
think the first step in building communication between threads should be
to look at java.util.concurrent, without preconceptions, to see whether
any of its classes does the job.

This is excellent advice, and i'm sorry i made you have to give it twice!
I thought that the OP might benefit from a suggestion of something
specific to look at within that package - it's a fairly broad collection
of classes, and can be daunting to a beginner.

tom

--
The real romance is out ahead and yet to come. The computer revolution
hasn't started yet. -- Alan Kay