I return a MergeCursor Instance from my content provider, wrapping a cursor from same content provider. Sounds weird, but I need it for data aggregation. Here is the code:
Cursor filteredLatest = getContext().getContentResolver().query(Latest.CONTENT_URI, ALL,
null, null, null);
return new MergeCursor(new Cursor[]{filteredLatest});
I do not use setNotificationUri here beause filteredLatest cursor is already has notification uri set up.
Everything goes smooth, I'm able to view data, until I update content provider with new data.
Then it dies with
10-18 00:15:19.441: E/AndroidRuntime(31491): android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 13
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.AbstractCursor.checkPosition(AbstractCursor.java:424)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:136)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.AbstractWindowedCursor.getLong(AbstractWindowedCursor.java:74)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.CursorWrapper.getLong(CursorWrapper.java:106)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.MergeCursor.getLong(MergeCursor.java:116)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.CursorWrapper.getLong(CursorWrapper.java:106)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.CursorAdapter.getItemId(CursorAdapter.java:220)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.AdapterView.rememberSyncState(AdapterView.java:1195)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:810)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:5998)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.CursorAdapter$MyDataSetObserver.onChanged(CursorAdapter.java:467)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.AbstractCursor.requery(AbstractCursor.java:137)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.sqlite.SQLiteCursor.requery(SQLiteCursor.java:234)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.CursorWrapper.requery(CursorWrapper.java:186)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.MergeCursor.requery(MergeCursor.java:228)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.CursorWrapper.requery(CursorWrapper.java:186)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.CursorAdapter.onContentChanged(CursorAdapter.java:443)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.widget.CursorAdapter$ChangeObserver.onChange(CursorAdapter.java:459)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.ContentObserver.onChange(ContentObserver.java:129)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.database.ContentObserver$NotificationRunnable.run(ContentObserver.java:180)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.os.Handler.handleCallback(Handler.java:730)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.os.Handler.dispatchMessage(Handler.java:92)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.os.Looper.loop(Looper.java:137)
10-18 00:15:19.441: E/AndroidRuntime(31491): at android.app.ActivityThread.main(ActivityThread.java:5103)
10-18 00:15:19.441: E/AndroidRuntime(31491): at java.lang.reflect.Method.invokeNative(Native Method)
10-18 00:15:19.441: E/AndroidRuntime(31491): at java.lang.reflect.Method.invoke(Method.java:525)
10-18 00:15:19.441: E/AndroidRuntime(31491): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-18 00:15:19.441: E/AndroidRuntime(31491): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-18 00:15:19.441: E/AndroidRuntime(31491): at dalvik.system.NativeStart.main(Native Method)
I've peeked into MergeCursor code and it seems like wrapped cursor is notified about data change and sets position of MergeCursor to -1. Then adapter is notified of change as well and it dies.
I'm not sure where to look for the bug.
My approach was wrong. After looking at Android dialer application I decided to write my own merging adapter instead of using flawed MergeCursor.