ListView Custom Adapter repeat items

Question

Whats wrong with this adapter, when i scroll down i see repeated rows at the bottom and then when scroll up again i see also repeated rows at the top that were not exist before, and the rest of Data items does not appear

the adapter:

public class ClassesListViewAdapter extends BaseAdapter {
    private Context mContext;
    ArrayList<String> Data = new ArrayList<>();


    public ClassesListViewAdapter(Context context, ArrayList<String> data) {
        Data = data;
        mContext = context;
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

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

    @Override
    public int getCount() {
        return Data.size();
    }
    private class ViewHolder{

        TextView ClassDataTV;

    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = ((Activity)mContext).getLayoutInflater();
        ViewHolder holder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.classes_list_view_item, parent, false);
            holder = new ViewHolder();
            holder.ClassDataTV = (TextView) convertView.findViewById(R.id.ClassDataTV);
            holder.ClassDataTV.setText(Data.get(position));
            convertView.setTag(holder);
        }else{
            holder=(ViewHolder)convertView.getTag();
        }

        return convertView;
    }
}

and here how i use it:

    ArrayList<String> v = new ArrayList<>();
    v.add("AAAAAAA");
    v.add("WWWWWwW");
    v.add("VVVVVVV");
    v.add("SSSSSSSSS");
    v.add("QQQQQQQQQ");
    v.add("YYYYYYYY");
    v.add("TTTTTTT");
    v.add("UUUUUUUUUU");
    v.add("zzzzzzzzzzzz");
    v.add("CCCCCCCCCC");
    v.add("HHHHHHHHHHH");
    v.add("IIIIIIIIII");
    v.add("PPPPPPPPP");
    mListView.setAdapter(new ClassesListViewAdapter(getActivity(), v));

The same thing happened to me, but my items repeated periodically like: A, B, C, D, A, B, C, D and so on. I fixed it with a solution I found here on StackOverflow. — Vucko, May 04 '16 at 20:53
@Amir, No but I calling `setAdapter` at `onResume` , will that be a problem ? — Atef Hares, May 04 '16 at 20:57
it's not recommend to setAdapter in onResume if I were you I do it in OnCreate | onCreatedView | onViewCreate — Amir, May 04 '16 at 20:59
@Amir, ok, i will take ur advice into consideration- Thanks for help — Atef Hares, May 04 '16 at 21:02

Amir · Accepted Answer · 2016-05-04T21:02:29.473

4

Put following part of your code outside if-block and it will be fixed :

  @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = ((Activity)mContext).getLayoutInflater();
        ViewHolder holder;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.classes_list_view_item, parent, false);
            holder = new ViewHolder();
            holder.ClassDataTV = (TextView) convertView.findViewById(R.id.ClassDataTV);

            convertView.setTag(holder);
        }else{
            holder=(ViewHolder)convertView.getTag();
        }

      // initialize your view here 
        holder.ClassDataTV.setText(Data.get(position));
        return convertView;
    }

The logic behind ViewHolder pattern tells that you should do it in this way. when you scroll some of reference will not created again and else block called so this cause your list not updated as you expected.

edited May 04 '16 at 21:02

answered May 04 '16 at 20:56

Amir

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2

While this is true you should also explain why. – cyroxis May 04 '16 at 20:56
1

Yes, it Worked perfectly – Atef Hares May 04 '16 at 21:00
1

[This](http://stackoverflow.com/questions/23995052/repeating-items-in-listview) is related to your problem and [the selected answer](http://stackoverflow.com/questions/23995052/repeating-items-in-listview) may shed some like. – ishmaelMakitla May 04 '16 at 21:00
@ishmaelMakitla, Thanks – Atef Hares May 04 '16 at 21:07

ListView Custom Adapter repeat items

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