title: How to make a delayed non-blocking function call
body: <p>I want to call the <code>add</code> function of an HashSet with some delay, but without blocking the current thread. Is there an easy solution to achieve something like this:</p>
  
  <pre><code>Utils.sleep(1000, myHashSet.add(foo)); //added after 1 second
  //code here runs immediately without delay
  ...
  </code></pre>