title: How to raise a toast in AsyncTask, I am prompted to used the Looper
body: <p>I have tasks completed by AsyncTask in background. At some point I need to issue a Toast that something is completed. </p>
  
  <p>I've tried and I failed because 
  <code>Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()</code></p>
  
  <p>How can I do that?</p>