JAVA多線程Callable應用

package concurrent;

import java.util.Random;
import java.util.concurrent.*;

/**
 * Auth: zhouhongliang
 * Date：2019/8/1
 * 分配多個線程共同執行某個任務，等待子線程都結束，主線程才結束
 */
public class CallableDemo {
    public static void main(String[] args) throws ExecutionException, InterruptedException {
        ExecutorService executorService = Executors.newFixedThreadPool(3);
        CountDownLatch countDownLatch = new CountDownLatch(3);
        Future<Integer> future1 = executorService.submit(new CallableTask(countDownLatch));
        Future<Integer> future2 = executorService.submit(new CallableTask(countDownLatch));
        Future<Integer> future3 = executorService.submit(new CallableTask(countDownLatch));
        System.out.println(future1.get());
        System.out.println(future2.get());
        System.out.println(future3.get());
        countDownLatch.await();
        executorService.shutdown();
    }
}
class CallableTask implements Callable<Integer>{
    private CountDownLatch countDownLatch;

    public CallableTask(CountDownLatch countDownLatch) {
        this.countDownLatch = countDownLatch;
    }

    @Override
    public Integer call() throws Exception {
        int count = 0;
        final int random = new Random().nextInt(1000);
        for (int i=0;i<random;i++){
            count ++;
        }
        countDownLatch.countDown();
        return count;
    }
}