线程交互

import java.util.concurrent.CountDownLatch;

public class LatchDriverDemo {
   private static final  int N = 5;
   public static void main(String[] args) throws InterruptedException {
    // 用于向工作线程发送启动信号
       CountDownLatch startSignal = new CountDownLatch(1);
    // 用于等待工作线程的结束信号 CountDownLatch
       CountDownLatch doneSignal = new CountDownLatch(N);
       for (int i = 0; i < N; i++)
        // 创建启动线程
        new Thread(new LatchWorker(startSignal,doneSignal),"t"+i).start();
        // 得到线程开始工作的时间
        long start = System.currentTimeMillis();
        //主线程，递减开始计数，让所有线程开始工作
        startSignal.countDown();
        //主线程开始阻塞，等待其他线程完成
        startSignal.await();
        long end = System.currentTimeMillis();

        //System.out.println("All Work Take Time : "+ (end - start)/1000.0+"s" );
        System.out.println(end+"   "+start);
   }
}

import java.util.concurrent.CountDownLatch;

public class LatchWorker implements Runnable{
    private final CountDownLatch startSignal;
    private final CountDownLatch doneSignal;
    public LatchWorker(CountDownLatch startSignal,CountDownLatch doneSignal){
        super();
        this.startSignal = startSignal;
        this.doneSignal = doneSignal;
    }
    @Override
    public void run() {
         try {
            startSignal.await();
            dowork();
            doneSignal.countDown();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
    private void dowork() {
        // TODO Auto-generated method stub
        int a = 0 ;
        for (int i = 0; i < 10000; i++) {
            a += 1;
        }
        System.out.println(Thread.currentThread().getName()+"="+a);
    }

}