Last section of SectionIndexer scrolls really fast

Question

Here's a short video of my problem. The last section of the list is scrolling really fast, as you can see by the scrollbar. Here's my code (the relevant parts):

public TotemAdapter (Activity activity, List<Totem> list) { 
        _activity = activity;
        totemList = list;
        showDelete = false;

        var items = list.ToArray ();

        alphaIndex = new Dictionary<string, int>();
        for (int i = 0; i < items.Length; i++) {
            var key = items[i].title[0].ToString();
            if (!alphaIndex.ContainsKey(key)) 
                alphaIndex.Add(key, i);
        }
        sections = new string[alphaIndex.Keys.Count];
        alphaIndex.Keys.CopyTo(sections, 0);
        sectionsObjects = new Java.Lang.Object[sections.Length];
        for (int i = 0; i < sections.Length; i++) {
            sectionsObjects[i] = new Java.Lang.String(sections[i]);
        }
    }

public int GetPositionForSection (int section) {
        return alphaIndex[sections[section]];
    }

    public int GetSectionForPosition(int position) {
        return 1;
    }

    public Java.Lang.Object[] GetSections () {
        return sectionsObjects;
    }

Does anyone know how I can fix this?

Thanks in advance.

Answer 1

I fixed it by returning 0 instead of 1 in GetSectionForPosition.

Answer 2

Returning a constant in getSectionForPosition can result in a misbehaviour of the scrollbar positioning when swiping through the list. Although your issue seem to be fixed, it acutally isn't. Documentation for the getSectionForPosition method says:

Given a position within the adapter, returns the index of the corresponding section within the array of section objects.

So when you swipe through your list, the section you're currently viewing will eventually change (e.g. you're reaching the 'B' section in your contacts). This method tells the scrollbar where it has to position itself when you swipe through your list (which is the counterpart to the getPositionForSection method which jumps to the section in the list when you scroll through your list using the scrollbar).

I provided a sample implemention of the getSectionForPosition method here.

Answer 3

You can use SetFriction method to control listview fast scroll speed. See an example at Android Listview slow down scroll speed