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ForEach 循环中使用多线程处理1

news 2026/5/12 13:54:22

引用：https://blog.csdn.net/m0_50932526/article/details/130204863

Java中如何使用CountDownLatch实现多线程同步，确保主线程在所有子线程执行完毕后继续执行。通过创建线程并使用CountDownLatch进行计数，主线程会等待所有子线程完成其任务后再执行后续代码，用于处理并发场景下的数据处理问题。

对for循环内数据启用多线程执行，主线程与子线程无先后顺序

    public static void main(String[] args) throws InterruptedException {for (int i = 0; i < 5; i++) {ThreadUtil.execAsync(() -> {try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("线程" + Thread.currentThread().getName() + "执行完");});System.out.println("第" + i + "个线程");}System.out.println("完成");}

执行结果：　　

对for循环内数据启用多线程执行，主线程在所有子线程执行完成之后执行

    public static void main(String[] args) throws InterruptedException {//初始化线程数量CountDownLatch countDownLatch = ThreadUtil.newCountDownLatch(5);for (int i = 0; i < 5; i++) {ThreadUtil.execute(() -> {try {Thread.sleep(1000);} catch (InterruptedException e) {e.printStackTrace();}System.out.println("线程" + Thread.currentThread().getName() + "执行完");//调用线程计数器-1
                countDownLatch.countDown();});System.out.println("第" + i + "个线程");}//唤醒主线程
        countDownLatch.await();System.out.println("完成");}

执行结果：

对for循环内数据启用多线程执行，主线程在所有子线程执行完成之后执行

 public static void main(String[] args) throws InterruptedException {// 线程个数int N = 10;// 实例化一个倒计数器，N指定计数个数CountDownLatch countDownLatch = new CountDownLatch(N);for (int i = 0; i < N; i++) {new Thread(new Runnable() {@Overridepublic void run() {try {Thread.sleep(5000);System.out.println("子线程" + Thread.currentThread().getName() + "休眠结束");} catch (Exception e) {e.printStackTrace();} finally {// 计数减一
                        countDownLatch.countDown(); }}}).start();}// 阻塞，等待当计数减到0时，执行后面的代码
        countDownLatch.await();System.out.println("结束");}

执行结果：

4 . JAVA多线程10个线程处理1000个数据

    public static void main(String[] args) throws Exception {List<Integer> idList = new ArrayList<>();for (int i = 1; i <= 1000; i++) {idList.add(i);}int threadNum = 10;ExecutorService executorService = Executors.newFixedThreadPool(threadNum);CountDownLatch countDownLatch = new CountDownLatch(threadNum);int perSize = idList.size() / threadNum;// 定义接受数据集合  多线程情况下，使用线程安全集合List<Integer> resultList = Collections.synchronizedList(new ArrayList());for (int i = 0; i < threadNum; i++) {MultiThread thread = new MultiThread();thread.setIdList(idList.subList(i * perSize, (i + 1) * perSize));thread.setCountDownLatch(countDownLatch);thread.setResultList(resultList);executorService.submit(thread);}countDownLatch.await();executorService.shutdown();// 查看结果
        System.out.println(resultList.size());System.out.println(resultList.stream().sorted().collect(Collectors.toList()));}
}class MultiThread extends Thread {private List<Integer> idList;private CountDownLatch countDownLatch;private List<Integer> result;public void setResultList(List<Integer> result) {this.result = result;}public void setIdList(List<Integer> idList) {this.idList = idList;}public void setCountDownLatch(CountDownLatch countDownLatch) {this.countDownLatch = countDownLatch;}@Overridepublic void run() {try {// 数据处理for (Integer integer : idList) {if (integer % 2 == 0) {result.add(integer);}}} catch (Exception e) {e.printStackTrace();} finally {if (countDownLatch != null) {countDownLatch.countDown();}}}