When should I use a CompletionService over an ExecutorService?

Question

I just found CompletionService in this blog post. However, this does\'t really showcases the advantages of CompletionService over a standard ExecutorService. The same code c

Answer 1

Let's say you have 5 long running task(callable task) and you have submitted those task to executer service. Now imagine you don't want to wait for all 5 task to compete instead you want to do some sort of processing on these task if any one completes. Now this can be done either by writing polling logic on future objects or use this API.