title: What causes Android's ContentResolver.query() to return null?
body: <p>Under what conditions does <a href="http://developer.android.com/reference/android/content/ContentResolver.html">ContentResolver.query</a>() return null instead of a cursor object?  I've gotten empty cursors before but just realized that the method can also return null.  I haven't been able to trace the circumstances that this happens in, though.</p>