CountDownLatch - latch.await() 可以理解為門栓栋盹，線程每完成一個執(zhí)行l(wèi)atch.countDown()，即為減1敷矫，直至減到0例获，latch.await() 才會執(zhí)行，new CountDownLatch(threads.length)設(shè)置線程的數(shù)量

import java.util.concurrent.CountDownLatch;

public class T06_TestCountDownLatch {
    public static void main(String[] args) {
        usingJoin();
        usingCountDownLatch();
    }

    private static void usingCountDownLatch() {
        Thread[] threads = new Thread[100];
        CountDownLatch latch = new CountDownLatch(threads.length);

        for(int i=0; i<threads.length; i++) {
            threads[i] = new Thread(()->{
                int result = 0;
                for(int j=0; j<10000; j++) result += j;
                latch.countDown();
            });
        }

        for (int i = 0; i < threads.length; i++) {
            threads[i].start();
        }

        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        System.out.println("end latch");
    }
    private static void usingJoin() {
        Thread[] threads = new Thread[100];

        for(int i=0; i<threads.length; i++) {
            threads[i] = new Thread(()->{
                int result = 0;
                for(int j=0; j<10000; j++) result += j;
            });
        }

        for (int i = 0; i < threads.length; i++) {
            threads[i].start();
        }
        for (int i = 0; i < threads.length; i++) {
            try {
                threads[i].join();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        System.out.println("end join");
    }
}

CyclicBarrier - 循環(huán)柵欄曹仗，即為滿了執(zhí)行榨汤。

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;
public class T07_TestCyclicBarrier {
    public static void main(String[] args) {
        // 參數(shù)1：設(shè)置待滿足的數(shù)量條件   參數(shù)2：條件滿足后 執(zhí)行的邏輯
        CyclicBarrier barrier = new CyclicBarrier(20, () -> System.out.println("滿人，發(fā)車"));
        /*CyclicBarrier barrier = new CyclicBarrier(20, new Runnable() {
            @Override
            public void run() {
                System.out.println("滿人怎茫，發(fā)車");
            }
        });*/

        for(int i=0; i<100; i++) {

                new Thread(()->{
                    try {
                        barrier.await();

                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    } catch (BrokenBarrierException e) {
                        e.printStackTrace();
                    }
                }).start();
        }
    }
}

• 場景 - 不同的線程處理不同的操作收壕，等待三個線程都完成的各自的操作之后，才能進行下一步操作轨蛤。

  
  
  屏幕快照 2021-01-01 上午1.30.51.png