Java parallel work iterator?

Question

I\'m looking for a class where I can override a method to do the work, and return the results like an iterator. Something like this:

ParallelWorkIterator<         


        

Answer 1

Have a look at the ExecutorCompletionService. It does everything you want.

   void solve(Executor e, Collection> solvers)
     throws InterruptedException, ExecutionException {
       //This class will hold and execute your tasks
       CompletionService ecs
           = new ExecutorCompletionService(e);
       //Submit (start) all the tasks asynchronously
       for (Callable s : solvers)
           ecs.submit(s);
       //Retrieve completed task results and use them
       int n = solvers.size();
       for (int i = 0; i < n; ++i) {
           Result r = ecs.take().get();
           if (r != null)
               use(r);
       }
   }

The benefit of using a CompletionService is that it always returns the first completed result. This ensures you're not waiting for tasks to complete and it lets the uncompleted tasks run in the background.