执行器中的Thread.join（）等价物

我有一个新手问题。 我有这个代码：

public class Main { public static void main(String[] args) throws InterruptedException { // TODO Auto-generated method stub IntHolder aHolder=new IntHolder(); aHolder.Number=0; IncrementorThread A= new IncrementorThread(1, aHolder); IncrementorThread B= new IncrementorThread(2, aHolder); IncrementorThread C= new IncrementorThread(3, aHolder); A.start(); B.start(); C.start(); A.join(); B.join(); C.join(); System.out.println("All threads completed..."); } } 

这将等待所有线程完成。 如果我像这样使用Executors ：

 public class Main { public static void main(String[] args) { // TODO Auto-generated method stub IntHolder aHolder=new IntHolder(); aHolder.number=0; IncrementalRunable A= new IncrementalRunable(1, aHolder); IncrementalRunable B= new IncrementalRunable(2, aHolder); IncrementalRunable C= new IncrementalRunable(3, aHolder); ExecutorService exec = Executors.newFixedThreadPool(3); exec.execute(A); exec.execute(B); exec.execute(C); //Don't know what to do here System.out.println("All threads completed..."); } } 

如何挂起主线程以等待执行程序中的所有线程完成，即在所有线程完成工作后应打印“所有线程完成…”？

Answer 1

 executor.shutdown(); while (!executor.awaitTermination(24L, TimeUnit.HOURS)) { System.out.println("Not yet. Still waiting for termination"); } 

使用shutdown() + awaitTermination()组合。

编辑：

根据@Lital的评论

 List> calls = new ArrayList>(); calls.add(Executors.callable(new IncrementalRunable(1, aHolder))); calls.add(Executors.callable(new IncrementalRunable(2, aHolder))); calls.add(Executors.callable(new IncrementalRunable(3, aHolder))); List> futures = executor.invokeAll(calls); 

注意： invokeAll()将不会返回，直到完成所有任务（通过失败或完成成功执行）。

Answer 2

如果要等待任务完成，则不应使用此类执行程序。 如果您不希望/无法关闭线程池执行程序，该怎么办？ 这是一种更推荐的方式：

  ExecutorService exec = Executors.newFixedThreadPool(3); Collection> tasks = new LinkedList>(); Future future = exec.submit(A); tasks.add(future); future = exec.submit(B); tasks.add(future); future = exec.submit(C); tasks.add(future); // wait for tasks completion for (Future currTask : tasks) { try { currTask.get(); } catch (Throwable thrown) { Logger.error(thrown, "Error while waiting for thread completion"); } } 

Answer 3

尝试以这种方式使用线程池。

 executor.shutdown(); executor.awaitTermination(MAX_PRIORITY, TimeUnit.HOURS); 

Answer 4

  exec.shutdown(); // Wait until all threads are finish exec.awaitTermination();