CountDownLatch用于阻塞一個線程脸爱，等待其它線程先后到達某個條件的時候瘪阁，再執(zhí)行這個線程的后續(xù)操作类浪。
public class CountDownLatchTest {
public static void main(String[] args) throws InterruptedException {
new CountDownLatchTest().go();
}
private void go() throws InterruptedException {
CountDownLatch countDownLatch = new CountDownLatch(3);
// 依次創(chuàng)建3個線程,并啟動
new Thread(new Task(countDownLatch), "Thread1").start();
Thread.sleep(1000);
new Thread(new Task(countDownLatch), "Thread2").start();
Thread.sleep(1000);
new Thread(new Task(countDownLatch), "Thread3").start();
countDownLatch.await();
System.out.println("所有線程已到達,主線程開始執(zhí)行" + System.currentTimeMillis());
}
class Task implements Runnable {
private CountDownLatch countDownLatch;
public Task(CountDownLatch countDownLatch) {
this.countDownLatch = countDownLatch;
}
@Override
public void run() {
System.out.println("線程" + Thread.currentThread().getName() + "已經到達" + System.currentTimeMillis());
countDownLatch.countDown();
}
}
}
運行結果：
線程Thread1已經到達1488870269086
線程Thread2已經到達1488870270091
線程Thread3已經到達1488870271092
所有線程已到達,主線程開始執(zhí)行1488870271093
可見，當Thread3到達以后轧叽，被阻塞的主線程立即開始執(zhí)行苗沧，時間戳的微小差異刊棕，在于線程的調度的時間消耗。
