java:等到另一个线程执行n次语句

Question

什么是停止线程并等待另一个线程执行一定次数的语句(或方法)的最佳方法？我正在考虑这样的事情(让"数字"成为一个int):

number = 5;
while (number > 0) {
   synchronized(number) { number.wait(); }
}

...

synchronized(number) {
   number--;
   number.notify();
}

显然这不起作用,首先是因为看起来你不能在int类型上等待().此外,对于我这样一个简单的任务来说,所有其他解决方案对我的Java天真的想法来说都非常复杂.有什么建议？(谢谢!)

Answer 1

听起来像你在寻找CountDownLatch.

CountDownLatch latch = new CountDownLatch(5);
...
latch.await(); // Possibly put timeout


// Other thread... in a loop
latch.countDown(); // When this has executed 5 times, first thread will unblock

A Semaphore也会起作用:

Semaphore semaphore = new Semaphore(0);
...
semaphore.acquire(5);

// Other thread... in a loop
semaphore.release(); // When this has executed 5 times, first thread will unblock