import java.util.concurrent.CountDownLatch; class Aworker implements Runnable { private int num; private CountDownLatch begin; private CountDownLatch end;  public Aworker(int num, final CountDownLatch begin, final CountDownLatch end) { this.num = num; this.begin = begin; this.end = end; }  @Override public void run() { // TODO Auto-generated method stub try {  System.out.println(num + "th people is ready");  begin.await();  //準(zhǔn)備就緒 } catch (InterruptedException e) {  e.printStackTrace(); } finally {  end.countDown();  //計(jì)數(shù)器減一，到達(dá)終點(diǎn)  System.out.println(num + "th people arrive"); } }} public class Race { public static void main(String[] args) { int num = 10; CountDownLatch begin = new CountDownLatch(1); CountDownLatch end = new CountDownLatch(num);  for (int i = 1; i <= num; i++) {  new Thread(new Aworker(i, begin, end)).start(); }  try {  Thread.sleep((long) (Math.random() * 5000)); } catch (InterruptedException e1) {  // TODO Auto-generated catch block  e1.printStackTrace(); }  System.out.println("judge say : run !"); begin.countDown(); //裁判一聲令下開始跑 long startTime = System.nanoTime(); try {  end.await(); //等待結(jié)束 } catch (InterruptedException e) {  // TODO Auto-generated catch block  e.printStackTrace(); } finally {  long endTime = System.nanoTime();  System.out.println("judge say : all arrived !");  System.out.println("spend time: " + (endTime - startTime)); } }}

1th people is ready2th people is ready4th people is ready6th people is ready3th people is ready10th people is ready8th people is ready5th people is ready7th people is ready9th people is readyjudge say : run !1th people arrive4th people arrive10th people arrive5th people arrive2th people arrivejudge say : all arrived !9th people arrive7th people arrive8th people arrive3th people arrive6th people arrivespend time: 970933