Return values from Java Threads

Question

I have a Java Thread like the following:

   public class MyThread extends Thread {
        MyService service;
        String id;
        public MyThread(Stri         


        

Answer 1

If you want to collect all of the results before doing the database update, you can use the invokeAll method. This takes care of the bookkeeping that would be required if you submit tasks one at a time, like daveb suggests.

private static final ExecutorService workers = Executors.newCachedThreadPool();

...

Collection> tasks = new ArrayList>();
for (final String id : ids) {
  tasks.add(new Callable()
  {

    public User call()
      throws Exception
    {
      return svc.getUser(id);
    }

  });
}
/* invokeAll blocks until all service requests complete, 
 * or a max of 10 seconds. */
List> results = workers.invokeAll(tasks, 10, TimeUnit.SECONDS);
for (Future f : results) {
  User user = f.get();
  /* Add user to batch update. */
  ...
}
/* Commit batch. */
...