title: java Callable FutureTask Excecuter: How to listen to finished task
body: <p>I'm quite new to executer services. Liked doing everything myself, but I think it's time to trust these services.</p>
  
  <p>I want to hand by <code>Executer</code> a <code>Runnable</code>. The executer wraps that in a <code>FutureTask</code> and hands it back to me. Now I call poll the <code>done()</code> method. But I would like to be notified when then <code>done()</code> method would return true.</p>
  
  <p>There is a <code>get()</code> method that blocks until the <code>Runnable</code> has finished, but then I would need a extra thread for every job, just to see when it's finished.</p>
  
  <p>Can I hand my executer some extra <code>Callable</code> to get notified about the task finishing?</p>
  
  <p>What's the way to go here? I could add some code to the end of the <code>run</code> method, but then <code>done()</code> might still be false...</p>