Use of FutureTask

Question

I have a class which implements Runnable and has a separate method for returning a result (few different methods because you can get various results) .. there is also some stuff that has to be done when cancelling/interrupting the running of this.
Now, I've been asked to use FutureTask
This is where I am stuck. I've read the tutorials, searched Google, but I can't find information on how to use Runnable classes with FutureTask - especially where I need to do more than the standard FutureTask Cancel method and where in different circumstances have to return different result types.
I was also confused about the constructor
FutureTask(Runnable runnable, V result)When I read the Java 1.5 code all this does is set the value of result to what is passed in the constructor... but how can that be when a result can't be set until you actually call runnable.run() method?
My first thought was to create a class which extends FutureTask and use the FutureTask(Runnable runnable, V result) constructor but then I can't figure out the rest.

Answer 1

Calling cancel on a FutureTask will attempt to prevent it from starting, and if it has started, it will attempt to interrupt it if you are using cancel(true).
The Task being run won't end magically. When a Thread is interrupted, is simply sets a flag which should be periodically checked by the task using if(Thread.interrupted()).
Your FutureTask won't be cancellable unless you make it so. And by making it cancellable, you'll already be aware of when to perform your cleanup. There's no need to subclass FutureTask.