 public static void main(String[] args) throws InterruptedException {
        final int NUM=6;
        //定義總數(shù)量；
        CountDownLatch countDownLatch=new CountDownLatch(NUM);
        for (int i = 0; i < NUM; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"線程，已執(zhí)行！");
                //減少計(jì)數(shù)
                countDownLatch.countDown();
            },String.valueOf(i+1)).start();
        }
        //等待所有任務(wù)完成
        countDownLatch.await();
        System.out.println("所有線程任務(wù)已經(jīng)執(zhí)行完成！");
    }

2、CyclicBarrier

與減少計(jì)數(shù)類似

 public static void main(String[] args) {
        final int NUM = 6;
        //定義循環(huán)數(shù)量及循環(huán)完成后的任務(wù)(Runnable接口實(shí)現(xiàn))；
        CyclicBarrier cyclicBarrier = new CyclicBarrier(NUM, () -> {
            System.out.println("所有線程任務(wù)已經(jīng)執(zhí)行完成！");
        });
        for (int i = 0; i < NUM; i++) {
            new Thread(()->{
                System.out.println(Thread.currentThread().getName()+"線程，已執(zhí)行！");
                try {
                    //等待點(diǎn)或障礙點(diǎn)，等待所有任務(wù)完成，
                    cyclicBarrier.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                } catch (BrokenBarrierException e) {
                    e.printStackTrace();
                }
            },String.valueOf(i+1)).start();
        }
    }

三、基于信號(hào)維度

Semaphore，線程與信號(hào)是m:n，其中m>=n。

import java.util.Random;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
/*信號(hào)燈
* 6個(gè)線程，搶占三個(gè)信號(hào)
* */
public class SemaphoreDemo {
    public static void main(String[] args) {
        Semaphore semaphore=new Semaphore(3);
        for (int i = 0; i < 6; i++) {
            new Thread(()->{
                try {
                    //獲取信號(hào)
                    semaphore.acquire();
                    System.out.println("線程："+Thread.currentThread().getName()+"----獲取信號(hào)");
                    int time = new Random().nextInt(5);
                    System.out.println(("線程："+Thread.currentThread().getName()+"----休眠"+time+"s！"));
                    TimeUnit.SECONDS.sleep(time);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }finally {
                //    釋放信號(hào)
                    System.out.println("線程："+Thread.currentThread().getName()+"---釋放信號(hào)");
                    semaphore.release();
                }
            },String.valueOf(i+1)).start();
        }
    }
}

首先線程4、1、3獲取到信號(hào)，線程1釋放信號(hào)后，線程2獲得信號(hào)。線程2、3釋放信號(hào)后，線程5、6獲得信號(hào)。