What is the difference between submit and execute method with ThreadPoolExecutor

Question

I found there are two ways (submit and execute) to add a Runnable into a thread pool, what is the difference?

Answer 1

The difference is that execute doesn't return a Future, so you can't wait for the completion of the Runnable and get any exception it throws using that.

Answer 2

Submit appears to be a more generic form of execute. In particular, submit returns a Future object that represents the result of the computation.

http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/ThreadPoolExecutor.html#execute(java.lang.Runnable)

http://download.oracle.com/javase/1.5.0/docs/api/java/util/concurrent/AbstractExecutorService.html#submit(java.util.concurrent.Callable)

Answer 3

The submit(...) method is executor framework extension introduced in ExecutorService interface.
It's main difference from execute(Runnable) is that it can accept Callable<V> (whereas execute() accepts only Runnable) and returns instance of Future<V>, which you can use later in caller to retrieve result of asynchronous computation (potentially blocking until computation is completed).