IllegalArgumentException and "thread still suspended after undo" after returning empty SQLite cursor

Question

When running my android application the ContentProvider returns an empty SQLite cursor (zero rows). This results in dalvikvm outputting the following message in LogCat:

threadid=1 still suspended after undo (sc=1 dc=1)

The debug tab in Eclipse show the following exception:

Thread [<1> main] (Suspended (exception IllegalArgumentException))  
    <VM does not provide monitor information>   
    AsyncTaskLoader$LoadTask.onPostExecute(Object) line: 63 
    AsyncTaskLoader$LoadTask(ModernAsyncTask).finish(Object) line: 461  
    ModernAsyncTask.access$500(ModernAsyncTask, Object) line: 47    
    ModernAsyncTask$InternalHandler.handleMessage(Message) line: 474    
    ModernAsyncTask$InternalHandler(Handler).dispatchMessage(Message) line: 99  
    Looper.loop() line: 213 
    ActivityThread.main(String[]) line: 5225    
    Method.invokeNative(Object, Object[], Class, Class[], Class, int, boolean) line: not available [native method]  
    Method.invoke(Object, Object...) line: 525  
    ZygoteInit$MethodAndArgsCaller.run() line: 741  
    ZygoteInit.main(String[]) line: 557 
    NativeStart.main(String[]) line: not available [native method]

I've logged every action in the OffersDatabaseHelper.OffersDatabaseHelper class. The method query returns a cursor to android.content.ContentProvider's method query wich seems to be the cause of the problem.

LogCat output:

03-13 14:12:20.116: I/System.out(2521): Sending WAIT chunk
03-13 14:12:20.116: I/dalvikvm(2521): Debugger is active
03-13 14:12:20.316: I/System.out(2521): Debugger has connected
03-13 14:12:20.316: I/System.out(2521): waiting for debugger to settle...
03-13 14:12:20.516: I/System.out(2521): waiting for debugger to settle...
03-13 14:12:20.716: I/System.out(2521): waiting for debugger to settle...
03-13 14:12:20.916: I/System.out(2521): waiting for debugger to settle...
03-13 14:12:21.117: I/System.out(2521): waiting for debugger to settle...
03-13 14:12:21.317: I/System.out(2521): waiting for debugger to settle...
03-13 14:12:21.517: I/System.out(2521): debugger has settled (1311)
03-13 14:12:21.537: V/OffersContentProvider(2521): onCreate called
03-13 14:12:21.537: I/OffersContentProvider(2521): setting context
03-13 14:12:21.537: I/OffersContentProvider(2521): setting dbHelper
03-13 14:12:21.537: I/OffersContentProvider(2521): initiating OffersDatabaseHelper
03-13 14:12:21.537: V/OffersContentProvider(2521): OffersDatabaseHelper.OffersDatabaseHelper called
03-13 14:12:21.557: I/OffersContentProvider(2521): Returning if offersDB is null
03-13 14:12:21.557: D/OffersContentProvider(2521): false
03-13 14:12:21.937: V/OffersContentProvider(2521): query called
03-13 14:12:21.977: I/OffersContentProvider(2521): CallerClassName=android.content.ContentProvider , Caller method name: query
03-13 14:12:21.987: I/OffersContentProvider(2521): Callee method name: query
03-13 14:12:21.987: D/OffersContentProvider - query - uri(2521): content://com.example.provider.offers/offers
03-13 14:12:21.997: D/OffersContentProvider - query - projection(2521): [offer_id, offer_title, offer_description, offer_distance, offer_icon, offer_reference]
03-13 14:12:22.007: D/OffersContentProvider - query - selection(2521): null
03-13 14:12:22.007: D/OffersContentProvider - query - selectionArgs(2521): null
03-13 14:12:22.007: D/OffersContentProvider - query - sort(2521): null
03-13 14:12:22.007: I/OffersContentProvider(2521): Instantiating SQLiteQueryBuilder with table offers
03-13 14:12:22.017: I/OffersContentProvider(2521): Instantiating SQLIteQueryBuilder succesful
03-13 14:12:22.017: I/OffersContentProvider(2521): Trying to match uri with 2
03-13 14:12:22.027: I/OffersContentProvider(2521): Could not match with uri
03-13 14:12:22.027: D/OffersContentProvider(2521): 1
03-13 14:12:22.027: I/OffersContentProvider(2521): Preparing orderBy
03-13 14:12:22.027: I/OffersContentProvider(2521): sort is empty, orderBy will be offer_distance ASC
03-13 14:12:22.027: I/OffersContentProvider(2521): Preparing to query the underlying database
03-13 14:12:22.027: D/libEGL(2521): loaded /vendor/lib/egl/libEGL_adreno.so
03-13 14:12:22.027: D/libEGL(2521): loaded /vendor/lib/egl/libGLESv1_CM_adreno.so
03-13 14:12:22.027: I/OffersContentProvider(2521): Querying underlying database successful
03-13 14:12:22.038: I/OffersContentProvider(2521): Dumping cursor
03-13 14:12:22.038: D/libEGL(2521): loaded /vendor/lib/egl/libGLESv2_adreno.so
03-13 14:12:22.038: D/OffersContentProvider(2521): android.database.sqlite.SQLiteCursor@41b8afa0
03-13 14:12:22.038: I/Adreno-EGL(2521): <qeglDrvAPI_eglInitialize:316>: EGL 1.4 QUALCOMM build:  (CL4169980)
03-13 14:12:22.038: I/Adreno-EGL(2521): OpenGL ES Shader Compiler Version: 17.01.10.SPL
03-13 14:12:22.038: I/Adreno-EGL(2521): Build Date: 12/01/13 Sun
03-13 14:12:22.038: I/Adreno-EGL(2521): Local Branch: 
03-13 14:12:22.038: I/Adreno-EGL(2521): Remote Branch: 
03-13 14:12:22.038: I/Adreno-EGL(2521): Local Patches: 
03-13 14:12:22.038: I/Adreno-EGL(2521): Reconstruct Branch: 
03-13 14:12:22.038: D/OffersContentProvider(2521): Cursor has 0 rows
03-13 14:12:22.038: I/OffersContentProvider(2521): Returing cursor
03-13 14:12:22.078: D/OpenGLRenderer(2521): Enabling debug mode 0
03-13 14:12:23.069: D/dalvikvm(2521): threadid=1: still suspended after undo (sc=1 dc=1)

Miscellaneous details:

• This problem occurs both on virtual devices and the Sony Xperia Z I'm testing with
• Android min-sdk = 11, target-sdk = 19

Any input on how to solve this problem is more than welcome, thank you in advance.

Answer 1

After continuing to dig I have just found out what is the cause of this particular problem. The debugger showed that SQLite gave me an exception telling me that the field _id was not present, wich was quite a surprise to me because my primary key wasn't _id.

Thanks to Al Sutton's answer on a different question I became aware that the primary field in my table was different from what SQLiteOpenHelper requires/

Changing the primary field to _id solved my problem.