How to wait for a ThreadPoolExecutor to finish

Question

My Question: How to execute a bunch of threaded objects on a ThreadPoolExecutor and wait for them all to finish before moving on?

I\'m new to Thread

Answer 1

Your issue seems to be that you are not calling shutdown after you have submitted all of the jobs to your pool. Without shutdown() your awaitTermination will always return false.

ThreadPoolExecutor ex =
    new ThreadPoolExecutor(limit, limit, 20, TimeUnit.SECONDS, q);
for (int i = 0; i < limit; i++) {
  ex.execute(new RunnableObject(i + 1));
}
// you are missing this line!!
ex.shutdown();
ex.awaitTermination(2, TimeUnit.SECONDS);

You can also do something like the following to wait for all your jobs to finish:

List> futures = new ArrayList>();
for (int i = 0; i < limit; i++) {
  futures.add(ex.submit(new RunnableObject(i + 1), (Object)null));
}
for (Future