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商丘做网站张,北京网站建设熊掌号,陕西多地最新通知,秋风最新消息简介在现实世界中#xff0c;我们常常需要等待其它任务完成#xff0c;才能继续执行下一步。Java实现等待子线程完成再继续执行的方式很多。我们来一一查看一下。 Thread的join方法该方法是Thread提供的方法#xff0c;调用join()时#xff0c;会阻塞主线程#xff0…简介在现实世界中我们常常需要等待其它任务完成才能继续执行下一步。Java实现等待子线程完成再继续执行的方式很多。我们来一一查看一下。 Thread的join方法该方法是Thread提供的方法调用join()时会阻塞主线程等该Thread完成才会继续执行代码如下 private static void threadJoin() {ListThread threads new ArrayList();for (int i 0; i NUM; i) {Thread t new Thread(new PkslowTask(Task i));t.start();threads.add(t);}threads.forEach(t - {try {t.join();} catch (InterruptedException e) {throw new RuntimeException(e);}});System.out.println(threadJoin Finished All Tasks...);} 结果 Task 6 is running Task 9 is running Task 3 is running Task 4 is running Task 7 is running Task 0 is running Task 2 is running Task 1 is running Task 5 is running Task 8 is running Task 1 is completed Task 8 is completed Task 6 is completed Task 4 is completed Task 3 is completed Task 0 is completed Task 7 is completed Task 9 is completed Task 2 is completed Task 5 is completed threadJoin Finished All Tasks... CountDownLatch CountDownLatch是一个很好用的并发工具初始化时要指定线程数如10。在子线程调用countDown()时计数减1。直到为0时await()方法才不会阻塞。代码如下 private static void countDownLatch() {CountDownLatch latch new CountDownLatch(NUM);for (int i 0; i NUM; i) {Thread t new Thread(() - {System.out.println(countDownLatch running...);try {Thread.sleep(1000);System.out.println(countDownLatch Finished...);latch.countDown();} catch (InterruptedException e) {throw new RuntimeException(e);}});t.start();}try {latch.await();} catch (InterruptedException e) {throw new RuntimeException(e);}System.out.println(countDownLatch Finished All Tasks...); } 结果 countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch running... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished... countDownLatch Finished All Tasks... CyclicBarrier CyclicBarrier与CountDownLatch类似但CyclicBarrier可重置可重用。代码如下 private static void cyclicBarrier() {CyclicBarrier barrier new CyclicBarrier(NUM 1);for (int i 0; i NUM; i) {Thread t new Thread(() - {System.out.println(cyclicBarrier running...);try {Thread.sleep(1000);System.out.println(cyclicBarrier Finished...);barrier.await();} catch (InterruptedException | BrokenBarrierException e) {throw new RuntimeException(e);}});t.start();}try {barrier.await();} catch (InterruptedException | BrokenBarrierException e) {throw new RuntimeException(e);}System.out.println(cyclicBarrier Finished All Tasks...); } 结果 cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier running... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished... cyclicBarrier Finished All Tasks... executorService.isTerminated() ExecutorService调用shutdown()方法后可以通过方法isTerminated()来判断任务是否完成。代码如下 private static void executeServiceIsTerminated() {ExecutorService executorService Executors.newFixedThreadPool(THREADS);IntStream.range(0, NUM).forEach(i - executorService.execute(new PkslowTask(Task i)));executorService.shutdown();while (!executorService.isTerminated()) {//waiting...}System.out.println(executeServiceIsTerminated Finished All Tasks...);} 结果 Task 0 is running Task 2 is running Task 1 is running Task 3 is running Task 4 is running Task 0 is completed Task 2 is completed Task 5 is running Task 4 is completed Task 7 is running Task 3 is completed Task 1 is completed Task 8 is running Task 6 is running Task 9 is running Task 5 is completed Task 9 is completed Task 7 is completed Task 6 is completed Task 8 is completed executeServiceIsTerminated Finished All Tasks... executorService.awaitTermination executorService.awaitTermination方法会等待任务完成并给一个超时时间代码如下 private static void executeServiceAwaitTermination() {ExecutorService executorService Executors.newFixedThreadPool(THREADS);IntStream.range(0, NUM).forEach(i - executorService.execute(new PkslowTask(Task i)));executorService.shutdown();try {if (!executorService.awaitTermination(1, TimeUnit.MINUTES)) {executorService.shutdownNow();}} catch (InterruptedException e) {throw new RuntimeException(e);}System.out.println(executeServiceAwaitTermination Finished All Tasks...); } 结果 Task 0 is running Task 1 is running Task 2 is running Task 3 is running Task 4 is running Task 0 is completed Task 5 is running Task 1 is completed Task 4 is completed Task 7 is running Task 3 is completed Task 8 is running Task 2 is completed Task 9 is running Task 6 is running Task 5 is completed Task 7 is completed Task 9 is completed Task 8 is completed Task 6 is completed executeServiceAwaitTermination Finished All Tasks... executorService.invokeAll 使用invokeAll提交所有任务代码如下 private static void executeServiceInvokeAll() {ExecutorService executorService Executors.newFixedThreadPool(THREADS);ListCallableVoid tasks new ArrayList();IntStream.range(0, NUM).forEach(i - tasks.add(new PkslowTask(Task i)));try {executorService.invokeAll(tasks);} catch (InterruptedException e) {throw new RuntimeException(e);}executorService.shutdown();System.out.println(executeServiceInvokeAll Finished All Tasks...); } 结果 Task 1 is running Task 2 is running Task 0 is running Task 3 is running Task 4 is running Task 1 is completed Task 3 is completed Task 0 is completed Task 2 is completed Task 4 is completed Task 8 is running Task 5 is running Task 6 is running Task 9 is running Task 7 is running Task 8 is completed Task 5 is completed Task 6 is completed Task 9 is completed Task 7 is completed executeServiceInvokeAll Finished All Tasks... ExecutorCompletionService ExecutorCompletionService通过take()方法会返回最早完成的任务代码如下 private static void executorCompletionService() {ExecutorService executorService Executors.newFixedThreadPool(10);CompletionServiceString service new ExecutorCompletionService(executorService);ListCallableString callables new ArrayList();callables.add(new DelayedCallable(2000, 2000ms));callables.add(new DelayedCallable(1500, 1500ms));callables.add(new DelayedCallable(6000, 6000ms));callables.add(new DelayedCallable(2500, 2500ms));callables.add(new DelayedCallable(300, 300ms));callables.add(new DelayedCallable(3000, 3000ms));callables.add(new DelayedCallable(1100, 1100ms));callables.add(new DelayedCallable(100, 100ms));callables.add(new DelayedCallable(100, 100ms));callables.add(new DelayedCallable(100, 100ms));callables.forEach(service::submit);for (int i 0; i NUM; i) {try {FutureString future service.take();System.out.println(future.get() task is completed);} catch (InterruptedException | ExecutionException e) {throw new RuntimeException(e);}}System.out.println(executorCompletionService Finished All Tasks...);executorService.shutdown();awaitTerminationAfterShutdown(executorService); } 这里不同任务的时长是不一样的但会先返回最早完成的任务 2000ms is running 2500ms is running 300ms is running 1500ms is running 6000ms is running 3000ms is running 1100ms is running 100ms is running 100ms is running 100ms is running 100ms is completed 100ms is completed 100ms task is completed 100ms task is completed 100ms is completed 100ms task is completed 300ms is completed 300ms task is completed 1100ms is completed 1100ms task is completed 1500ms is completed 1500ms task is completed 2000ms is completed 2000ms task is completed 2500ms is completed 2500ms task is completed 3000ms is completed 3000ms task is completed 6000ms is completed 6000ms task is completed executorCompletionService Finished All Tasks... 代码代码请看GitHub: https://github.com/LarryDpk/pkslow-samples

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