cursor index out of bounds "index 0 requested: with size 0" error

Question

I got this exception when i run the project, here is part of main activity

  private void fillData() {
    // Get all of the notes from the database and create the item list
    Cursor notesCursor = mDbHelper.fetchAllNotes();

    if (notesCursor != null) {
        notesCursor.moveToFirst();
        do {
            messagesList.add(notesCursor.getString(notesCursor
                    .getColumnIndex(DbAdapter.KEY_FIELD2)));
            Log.e("Test", notesCursor.getString(notesCursor
                    .getColumnIndex(DbAdapter.KEY_FIELD2)));

        } while (notesCursor.moveToNext());
    }
    customAdapter.notifyDataSetChanged();
    // setListAdapter(notes);
}

code of `fetchAllNotes()` method. and Error log please – Lucifer Apr 16 '14 at 10:44 — Lucifer, Apr 16 '14 at 10:44

Jeje Doudou · Answer 1 · 2014-04-16T11:07:56.003

First of all, you should test notesCursor != null AND notesCursor.moveToNext() (which returns a boolean). Having a cursor not null doesn't mean it has results to give. And moreover, you use the do/while loop, which means you suppose you'll always have as leats one result...

I would say you should use this instead:

private void fillData() {
    // Get all of the notes from the database and create the item list
    Cursor notesCursor = mDbHelper.fetchAllNotes();

    if (notesCursor != null) {
        while(notesCursor.moveToNext())
        {
            messagesList.add(notesCursor.getString(notesCursor
                    .getColumnIndex(DbAdapter.KEY_FIELD2)));
            Log.e("Test", notesCursor.getString(notesCursor
                    .getColumnIndex(DbAdapter.KEY_FIELD2)));
        }
        customAdapter.notifyDataSetChanged();
    }
}

And I also think you should only call notifyDataSetChanged() if some modifications were done: so move it INSIDE your if clause: You don't have to ask your system to re-calculate your ListView if nothing as changed...

Typically, your error may occur when calling moveToNext: Your cursor doesn't have any result but you ask it to move to next... Next of what? If no result, no way to move to next...

Sure it can be null, see this thread: http://stackoverflow.com/questions/13080540/what-causes-androids-contentresolver-query-to-return-null — Jeje Doudou, Apr 16 '14 at 11:02
OOOOOPS!! MoveToNext! What a shame! You're right Selvin! :o Just edited the code... ^_^ — Jeje Doudou, Apr 16 '14 at 11:07

Zohra Khan · Answer 2 · 2014-04-16T11:10:52.337

SQliteDatabase.query() returns a Cursor object, which is positioned before the first entry. Cursor is never null but it can be empty. Your query() will either return a Cursor object or it will throw an exception. It will never return null.

boolean moveToFirst():

returns false if cursor is empty otherwise it will move cursor to the first row of the result and returns true.

You can check something like this:

notesCursor.moveToFirst();

while(notesCursor.moveToNext())
        {
            messagesList.add(notesCursor.getString(notesCursor
                    .getColumnIndex(DbAdapter.KEY_FIELD2)));
            Log.e("Test", notesCursor.getString(notesCursor
                    .getColumnIndex(DbAdapter.KEY_FIELD2)));
        }
        customAdapter.notifyDataSetChanged();
    }

Sure it can be null see this thread: http://stackoverflow.com/questions/13080540/what-causes-androids-contentresolver-query-to-return-null — Jeje Doudou, Apr 16 '14 at 11:03

cursor index out of bounds "index 0 requested: with size 0" error

2 Answers2