对于倒计时器锁，一种典型的应用就是火箭发射。火箭发射前，要等待所有的检测线程完工。CountDownLatch接受一个整数作为参数，即当前计数器的计数个数。
下面的这个例子演示了一个模拟的火箭发射过程：
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package fuck;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class implements Runnable{
private static CountDownLatch cdLatch = new CountDownLatch(10);
private int value;
public static void main(String[] args) throws Exception {
final Shit shit = new Shit();
ExecutorService exec = Executors.newFixedThreadPool(10);
for(int i=0;i<10;i++) {
exec.submit(shit);
}
cdLatch.await();
System.out.println("Fire!");
exec.shutdown();
}
public void run() {
try {
Thread.sleep(new Random().nextInt(10)*1000);
System.out.println("Check Over !");
cdLatch.countDown();
}catch(InterruptedException e) {
e.printStackTrace();
}
}
}
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调用cdLatch.await()后，该线程将会等待子线程countdown完毕后才能执行。
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