What's the difference between Future and FutureTask in Java?

Question

Since use ExecutorService can submit a Callable task and return a Future, why need to use FutureTask to wrap

Answer 1

Future is just interface. Behind the scene, the implementation is FutureTask.

You can absolutely use FutureTask manually but you will lose the advantages of using Executor (pooling thread, limit the thread, etc). Using FutureTask is quite similar to using the old Thread and using the run method.