title: Android: findviewbyid: finding view by id when view is not on the same layout invoked by setContentView
body: <p>I have an activity MyActivity that extends from MapActivity. In the .xml file containing the layout I can only include the MapView</p>
  
  <pre><code>&lt;com.google.android.maps.MapView
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:id="@+id/trail_map_view"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"
      android:clickable="true"
      android:apiKey="key"
  /&gt;
  </code></pre>
  
  <p>However I do need to find another view that is located in another .xml file.
  Unfortunately, findViewById returns null.
  How can I get the view I am looking for?</p>
  
  <p>Thanks a lot!</p>