CountDownLatch 使用場景

/**
 * 第一個使用場景
 * 數據使用多線程的方式處理
 */
public class CountDownLatchTest {

    private static ExecutorService executor = newFixedThreadPool(2);

    private static final CountDownLatch latch = new CountDownLatch(10);

    public static void main(String[] args) throws InterruptedException {
        int[] data = query();
        for(int i = 0;i < data.length ; i++){
            executor.submit(new SimpleThread(data,latch,i));
        }
        executor.shutdown();
        latch.await();
        System.out.println("main thread end");

    }


    public static int[] query(){
        return new int[]{1,2,3,4,5,6,7,8,9,10};
    }

}

class SimpleThread extends Thread{

    private final int[] data;

    private final CountDownLatch latch;

    private final int i;

    public SimpleThread(int[] data, CountDownLatch latch, int i) {
        this.data = data;
        this.latch = latch;
        this.i = i;
    }

    @Override
    public void run() {
        try {
            Thread.sleep(1000);
            latch.countDown();
            if(data[i] % 2 == 0){
                data[i] = data[i] + 10;
            }
            System.out.println(Thread.currentThread().getName() + " " + data[i]);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

/**
 * 第二個使用場景，就是當一個任務做完的時候，在第二個任務執行一半的時候需要用到第一個任務的結果集
 * 那麼在第二個任務使用 await 方法處理即可
 */