Android: SortedList with duplicates

Question

I have some problems understanding RecyclerViews SortedList.

Lets say I have a very simple class only having a very simple class holding data:<

Answer 1

As Minhtdh already mentioned in his answer, the problem lies within your compare().

See, add() looks up the existing object's index by using the compare() you implement. Therefore when your compare() returns something other than 0 it adds the object to the list.

You would need to check if the items are the same before comparing it's contents. However, if your content can be the same you would need a secondary comparison.

This is how I would implement the compare() in your case:

@Override
public int compare(Pojo o1, Pojo o2) {
    int result;
    if (areItemsTheSame(o1, o2) {
        result = 0;
    } else {
        result = Character.compare(o1.aChar, o2.aChar);
        if (result == 0) {
            // TODO implement a secondary comparison 
        }
    }

    return result;
}