Looping over cursor not same count as cursor count on android

Question

In my app I´m using a SimpleCursorAdapter to display contacts.

Each view has it´s own checkbox. in order to check all, I´m going through the cursor, putting each ID to a Set, which is progressed by the getView() method to trigger checkboxes.

The problem is here:

   int counter = 0;
   if (cursor.moveToFirst())
            while (cursor.moveToNext()) {
                contact_ids_to_skip.add(cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID)));
                counter++;

            }

The first list entry is always triggered, because counter is 157, and cursor.getCount() is 158.

I do not know what is happening here. I thought cursor.moveToFirst() is putting the cursor into its right position, but thats not the case.

How can I solve this?

Edit: I read the contact id from the first view which wont get unchecked at any point, and it is not getting added to the set in the upper code

Answer 1

Look at your logic. First, you move to the first record. Immediately after that, you moveToNext(). The first item is being skipped.

A few options:

Move the moveToNext() call to the end of the loop:

   int counter = 0;
   if (cursor.moveToFirst())
            do {
                contact_ids_to_skip.add(cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID)));
                counter++;
            } while(cursor.moveToNext())

Change moveToFirst() to moveToPosition(-1):

   int counter = 0;
   if (cursor.moveToPosition(-1))
            while (cursor.moveToNext()) {
                contact_ids_to_skip.add(cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID)));
                counter++;
            }

Or, simply get rid of moveToFirst() altogether:

   int counter = 0;
   while (cursor.moveToNext()) {
       contact_ids_to_skip.add(cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts._ID)));
       counter++;
   }

The last works because when a Cursor is returned from any query method, it's position is -1, which is "before the first item". So, a moveToNext() puts it in the right spot. Only use that one if the Cursor has just been returned from a query, though. If its position has been changed, use one of the first two methods.