title: What is the point of super.onStop()?
body: <p>I started learning how to create an app on Android. I have a bit of knowledge on Java already, and now I'm trying some of the activity events.</p>
  
  <p>I know how to use <code>onCreate</code> or <code>onCreateOptionsMenu</code>, and now I'm testing out <code>onStop</code>:</p>
  
  <pre><code>@Override
  public void onStop(){
      //a function that simply creates and return an AlertDialog.Builder object
      displayPopup("Event", "Stopped", "OK").show();
  }
  </code></pre>
  
  <p>I thought this would work since there's no error at compile time. But when I try to exit the app, I expect a popup dialog would show up but instead the app just crashed. It turns out that I need one extra line to make it work:</p>
  
  <pre><code>super.onStop();
  </code></pre>
  
  <p>It doesn't do anything (at least I can't see anything changed) and it's kind of useless, but without this line the app just keeps crashing.</p>
  
  <p>Any help would be great, thanks.</p>