title: `Can't create handler...Looper.prepare()` in inherited Activity
body: <p>I have a Game <code>Activity</code> (Activity A) that works well with all the code. Then I create a new <code>Activity</code> (Activity B) for my new game mode, that <code>extends</code> Activity A. However, when encounter the Toast line, Activity B suddenly thrown an exception (Activity A works well showing the Toast):</p>
  
  <p><code>Can't create handler inside thread that has not called Looper.prepare()</code></p>
  
  <p>Activity B only overrides a load-level method, no any differrence!</p>