Working with SQLite Cursors

A common mistake is the improper way to use cursors. It is very common to use a cursor and forget to close it. This produce an IllegalStateException.

A code similar to the following code example will produce an error the moment you leave the activity:

private void readContactData(long contactDataId) {
   Log.d(TAG, 'readContactData()');
   dbContact.open();
   Cursor cursor = dbContact.getContact(contactDataId);
   if (cursor.moveToFirst()) {
     ...
   } else {
     ...
   }
   dbContact.close();
   ...
}
The         problem         is         that         you         are         not         closing         the         cursor         properly.

You         could         try         the         following         variable         of         the         previous         code:
private void readContactData(long contactDataId) {
   Log.d(TAG, 'readContactData()');
   dbContact.open();
   Cursor cursor = dbContact.getContact(contactDataId);
   if (cursor.moveToFirst()) {
     ...
   } else {
     ...
   }
   cursor.close();
   dbContact.close();
   ...
}

However,                  there         are         cases         that         this         code         produce         a         warning         when         cursor         calls         the                  method         finalizer().         This         seems         to         be         a         problem         with         Droid         2.
This         method         seems         to         work         better:
private void readContactData(long contactDataId) {
    Log.d(TAG, 'readContactData()');
    Cursor cursor = null;
    try{
        dbContact.open();
        cursor = dbContact.getContact(contactDataId);
        if (cursor.moveToFirst()) {
            ...
        } else {
            ...
        }
        dbContact.close();
    }finally{
        if (cursor != null){
            cursor.deactivate();
            cursor.close();
        }
    }
}
Finally,         there         is         always         the         option         of         using         startManagingCursor();         however,         this         will         be         deprecated         and         replaced         with         CursorLoader class         when         using         API         11.
© 2011, Alejandro G. Carlstein Ramos Mejia. All rights reserved.