title: Android - shared_prefs missing items
body: <p>I'm confused by the way preferences seem to work in Android.</p>
  
  <p>In my Android Studio project I have an xml file containing all my preferences:</p>
  
  <p>app/src/main/res/xml/system_preferences.xml</p>
  
  <p>In my main activity I call the following to fetch preferences:</p>
  
  <pre><code>SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
  </code></pre>
  
  <p><code>prefs.mMap</code> contains only some of the preferences from system_preferences.xml, why would some be missing? </p>
  
  <p>Using ADB shell I see /data/data/com.my.app/shared_prefs/com.my.app_preferences.xml which contains the same subset of preferences.</p>
  
  <p>How do I find my missing preferences?</p>
  
  <p><strong>UPDATE</strong>: my system_preferences.xml is actually a PreferenceScreen xml file.</p>