title: Running code in main thread from another thread
body: <p>In an android service I have created thread(s) for doing some background task.</p>
  <p>I have a situation where a thread needs to post certain task on main thread's message queue, for example a <code>Runnable</code>.</p>
  <p>Is there a way to get <code>Handler</code> of the main thread and post <code>Message</code>/<code>Runnable</code> to it from my other thread?</p>