/*

 * CountDownLatch ：闭锁，在完成某些运算是，只有其他所有线程的运算全部完成，当前运算才继续执行

 */

public class TestCountDownLatch {

    public static void main(String[] args) {

        final CountDownLatch latch = new CountDownLatch(50);

        LatchDemo ld = new LatchDemo(latch);

        long start = System.currentTimeMillis();

        for (int i = 0; i < 50; i++) {

            new Thread(ld).start();

        }

        try {

            latch.await();

        } catch (InterruptedException e) {

        }

        long end = System.currentTimeMillis();

        System.out.println("耗费时间为：" + (end - start));

    }

}

class LatchDemo implements Runnable {

    private CountDownLatch latch;

    public LatchDemo(CountDownLatch latch) {

        this.latch = latch;

    }

    @Override

    public void run() {

        try {

            for (int i = 0; i < 50000; i++) {

                if (i % 2 == 0) {

                    System.out.println(i);

                }

            }

        } finally {

            latch.countDown();

        }

    }

}