custom list adapter unintentional rearranging

Question

I wrote a an ArrayAdapter to be used in my ListActivity but for some reason when i scroll down and then scroll back up the order of my list is being rearranged and i have no idea why. The initial order of the items when the items are loaded is correct. The problem is when i scroll down and get a few of the top items off the screen and then scroll back up to them, they're different. My ArrayList isn't being changed from an outside source. Can someone see where i'm going wrong?

public class List3ItemAdapter extends ArrayAdapter {

    private final static String DBG = "List3ItemAdapter";
    private Activity activity;
    private ArrayList<GenericListItem> listItems;
    private static LayoutInflater inflater;
    private ArrayList<View> listViews;

    public List3ItemAdapter(Activity activity, ArrayList<GenericListItem> listItems) {

        super(activity, android.R.layout.simple_list_item_1);

        this.listItems = listItems;

        this.activity = activity;

        this.listViews = new ArrayList<View>();



        inflater = (LayoutInflater) activity.getSystemService(activity.LAYOUT_INFLATER_SERVICE);
    }

    public int getCount() {
        return listItems.size();
    }

    public Object getItem(int position) {
        return listItems.get(position);
    }

    public long getItemId(int position) {
        return position;
    }

    public View getViewByPos(int pos) {
        return listViews.get(pos);
    }

    public View getView(int position, View convertView, ViewGroup parent) {

        //   Log.d(DBG, "current position is: " + position);
        View vi = convertView;

        GenericListItem listItem = listItems.get(position);

        ArrayList<String> values = listItem.getDisplayValues();


        if (vi == null) {

            if (listItem.getIsSection()) {
                vi = inflater.inflate(R.layout.list_section, null);
            } else {
                vi = inflater.inflate(R.layout.list_3itemrow, null);
            }

            listViews.add(vi);
        }

        if (listItem.getIsSection()) {

            TextView sectionTitle = (TextView) vi.findViewById(R.id.sectionTitle);
            sectionTitle.setText(values.get(0));

        } else {

            TextView title = (TextView) vi.findViewById(R.id.primaryTitle);
            TextView secondary = (TextView) vi.findViewById(R.id.secondaryTitle);
            TextView rightData = (TextView) vi.findViewById(R.id.rightData);

            secondary.setVisibility(View.GONE);
            rightData.setVisibility(View.GONE);

            Integer count = 0;

            for (String str : values) {
                count++;

                if (count == 1) {

                    title.setText(str);

                } else if (count == 2) {

                    secondary.setText(str);
                    secondary.setVisibility(View.VISIBLE);

                } else if (count == 3) {

                    rightData.setText(str);
                    rightData.setVisibility(View.VISIBLE);
                }
            }

        }

        return vi;
    }
}

Bartek Filipowicz · Answer 1 · 2013-05-20T20:11:41.993

2

No need for ArrayAdapter, since you're providing your own getView(), and are handling getItem()by yourself. BaseAdapter should do the work.
If you want to have 2 kinds of views, use getItemViewType(int position) and getViewTypeCount(). The second should return two, and the first one should return 0 for the header and 1 for the content. This way you will enable the ListView to recycle the views correctly.
In getView() check the type of the view using getItemViewType(int position), and inflate or reuse (if provided) a proper view (header or content). Basing on the type of view, fill the content.
The inflater should not be static. The adapter is bind to the activity and should probably not hold static references to anything that's connected to it. Unless you have a valid reason, don't use static variables for such stuff :) Also, there is a useful shortcut for getting the LayoutInflater: LayoutInflater.from(context)

edited May 20 '13 at 20:11

answered May 20 '13 at 19:59

Bartek Filipowicz

1,235
7
9

1

I would add: listViews.add(vi); in pair with getViewByPos is meaningless due to view recycling. – alexei burmistrov May 20 '13 at 20:10
I don't understand how to use getItemViewType() or getViewTypeCount(), can you point me to a tutorial? – David May 20 '13 at 20:18
there's also a nice explanation here: http://stackoverflow.com/questions/5300962/getviewtypecount-and-getitemviewtype-methods-of-arrayadapter – Bartek Filipowicz May 20 '13 at 20:35
in your case, you could make getItemViewType(position) look like this: return listItems.get(position).getIsSection() ? 0 : 1 – Bartek Filipowicz May 20 '13 at 20:37
alright, i think i understand now. I couldn't make the connection between getItemViewType(position) and the actual listitems. thanks – David May 20 '13 at 20:49

custom list adapter unintentional rearranging

1 Answers1