title: onDestroy() - to set or not to set instance variables to null?
body: <p>Is it a good idea to specifically set the instance variables to null in onDestroy() callback of the activity? Something like this:</p>
  
  <pre><code>    @Override
  protected void onDestroy() {
      super.onDestroy();
      mClassVariable1 = null;
      mClassVariable2 = null;
      mClassVariable3 = null;
  }
  </code></pre>
  
  <p>If I remember correctly from Java SE, any references that are isolated &amp; not connected to a running program &amp; can be garbage collected anyways. So does this make the above superfluous?</p>
  
  <p>On the other hand, the lifecycle in mobile devices being different, would the above be a best-practice?</p>
  
  <p>I know it <em>cannot hurt</em> to do it, but sometimes there are a number of class variable (references to indivudual UI elements etc), so I'd really like to know for my own understanding, what's really going on.</p>
  
  <p>Thanks in advance! </p>