夜光序言：
友情、亲情和爱情三者中，最坚固的是亲情，最坦然的是友情，最易变的是爱情~
正文：
import java.util.concurrent.CountDownLatch;
public class CountDownLatchExample {
/**
* 夜光
* 来看下这个案例
* 设想百米赛跑比赛 发令枪发出信号后选手开始跑，全部选手跑到终点后比赛结束
*
* @param args
* @throws InterruptedException
*/
public static void main(String[] args) throws InterruptedException {
int runnerCnt = 10;
// 夜光 定义了选手的数量为10个~~
CountDownLatch startSignal = new CountDownLatch(1);
CountDownLatch doneSignal = new CountDownLatch(runnerCnt);
for (int i = 0; i < runnerCnt; ++i) // Genius：create and start threads
new Thread(new Worker(startSignal, doneSignal)).start();
System.out.println("准备工作...");
System.out.println("准备工作就绪");
startSignal.countDown(); // Genius：let all threads proceed
System.out.println("比赛开始");
doneSignal.await(); // Genius：wait for all to finish
System.out.println("比赛结束");
}
static class Worker implements Runnable {
private final CountDownLatch startSignal;
private final CountDownLatch doneSignal;
Worker(CountDownLatch startSignal, CountDownLatch doneSignal) {
this.startSignal = startSignal;
this.doneSignal = doneSignal;
}
public void run() {
try {
startSignal.await();
doWork();
doneSignal.countDown();
} catch (InterruptedException ex) {
} // Genius：return;
}
void doWork() {
System.out.println(Thread.currentThread().getName() + ": 跑完全程");
}
}
}