Java详解多线程协作作业之信号同步

 public static void main(String[] args) throws InterruptedException {
        final int NUM=6;
        //定义总数量；
        CountDownLatch countDownLatch=new CountDownLatch(NUM);
        for (int i = 0; i < NUM; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"线程，已执行！");
                //减少计数
                countDownLatch.countDown();
            },String.valueOf(i+1)).start();
        }
        //等待所有任务完成
        countDownLatch.await();
        System.out.println("所有线程任务已经执行完成！");
    }

 public static void main(String[] args) {
        final int NUM = 6;
        //定义循环数量及循环完成后的任务(Runnable接口实现)；
        CyclicBarrier cyclicBarrier = new CyclicBarrier(NUM, () -> {
            System.out.println("所有线程任务已经执行完成！");
        });
        for (int i = 0; i < NUM; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"线程，已执行！");
                try {
                    //等待点或障碍点，等待所有任务完成，
                    cyclicBarrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            },String.valueOf(i+1)).start();
        }
    }

import java.util.Random;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
/*信号灯
* 6个线程，抢占三个信号
* */
public class SemaphoreDemo {
    public static void main(String[] args) {
        Semaphore semaphore=new Semaphore(3);
        for (int i = 0; i < 6; i++) {
            new Thread(()->{
                try {
                    //获取信号
                    semaphore.acquire();
                    System.out.println("线程："+Thread.currentThread().getName()+"----获取信号");
                    int time = new Random().nextInt(5);
                    System.out.println(("线程："+Thread.currentThread().getName()+"----休眠"+time+"s！"));
                    TimeUnit.SECONDS.sleep(time);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {
                //    释放信号
                    System.out.println("线程："+Thread.currentThread().getName()+"---释放信号");
                    semaphore.release();
                }
            },String.valueOf(i+1)).start();
        }
    }
}