Equivalent to wait (x == 0) in Java

Question

In, for example, Pthreads it is possible to wait for a process for a certain condition, for example:

<await (nr == 0 ^ nw == 0) nw++>;

Is there a way to do this in a similar way using Semaphores in Java? Waiting for a condition such as nr == 0.

+3

Rickard Feb 17 13 at 21:29

2 answers

public void setX(int a) {
    x = a;
    if(x==0) {
         //do stuff
    }
}

Then use this installer instead x = a

.

0

Doorknob Feb 17 13 at 21:37

assylias · Accepted Answer · 2013-02-17T21:34:33+0000

If it's a one-off event, you can use aCountDownLatch

:

private final CountDownLatch xIsZeroLatch = new CountDownLatch(1);

Then you use it like this:

in a waiting thread:

xIsZeroLatch.await();

in the other thread (s):

x = newX();
if (x == 0) xIsZeroLatch.countDown();

If a condition can change multiple times between true and false, and each change requires an event, you can use Semaphore

with one resolution.