notifyDataSetChange not working from custom adapter

Question

When I repopulate my ListView, I call a specific method from my Adapter.

Problem:

When I call updateReceiptsList from my Adapter, the data is refreshed, but my ListView doesn't reflect the change.

Question:

Why doesn't my ListView show the new data when I call notifyDataSetChanged?

Adapter:

public class ReceiptListAdapter extends BaseAdapter {

    public List<Receipt> receiptlist;
    private Context context;
    private LayoutInflater inflater;
    private DateHelpers dateH;

    public ReceiptListAdapter(Activity activity, Context mcontext, List<Receipt> rl) {
        context = mcontext;
        receiptlist = rl;
        Collections.reverse(receiptlist);
        inflater = (LayoutInflater)activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        dateH = new DateHelpers();
    }

    @Override
    public int getCount() {
        try {
            int size = receiptlist.size();
            return size;
        } catch(NullPointerException ex) {
            return 0;
        }
    }

    public void updateReceiptsList(List<Receipt> newlist) {
        receiptlist = newlist;
        this.notifyDataSetChanged();
    }

    @Override
    public Receipt getItem(int i) {
        return receiptlist.get(i);
    }

    @Override
    public long getItemId(int i) {
        return receiptlist.get(i).getReceiptId() ;
    }

    private String getPuntenString(Receipt r) {
        if(r.getPoints().equals("1")) {
            return "1 punt";
        }
        return r.getPoints()+" punten";
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View vi=convertView;

        final Receipt receipt = receiptlist.get(position);
        ReceiptViewHolder receiptviewholder;
        Typeface tf_hn = Typeface.createFromAsset(context.getAssets(), "helveticaneue.ttf");        
        Typeface tf_hn_bold = Typeface.createFromAsset(context.getAssets(), "helveticaneuebd.ttf");

        if (vi == null) { //convertview==null
            receiptviewholder = new ReceiptViewHolder();
            vi = inflater.inflate(R.layout.view_listitem_receipt, null);
            vi.setOnClickListener(null);
            vi.setOnLongClickListener(null);
            vi.setLongClickable(false);
            receiptviewholder.shop = (TextView) vi.findViewById(R.id.tv_listitemreceipt_shop);
            receiptviewholder.date = (TextView) vi.findViewById(R.id.tv_listitemreceipt_date);
            receiptviewholder.price = (TextView) vi.findViewById(R.id.tv_listitemreceipt_price);
            receiptviewholder.points = (TextView) vi.findViewById(R.id.tv_listitemreceipt_points);
            receiptviewholder.shop.setTypeface(tf_hn_bold);
            receiptviewholder.price.setTypeface(tf_hn_bold);
            vi.setTag(receiptviewholder);
        }else{//convertview is not null
            receiptviewholder = (ReceiptViewHolder)vi.getTag();
        }

        receiptviewholder.shop.setText(receipt.getShop());
        receiptviewholder.date.setText(dateH.timestampToDateString(Long.parseLong(receipt.getPurchaseDate())));
        receiptviewholder.price.setText("€ "+receipt.getPrice());
        receiptviewholder.points.setText(getPuntenString(receipt));

        vi.setClickable(false);
        return vi;
    }

    public static class ReceiptViewHolder {
        public TextView shop;
        public TextView date;
        public TextView price;
        public TextView points;
    }

    public Object getFilter() {
        // XXX Auto-generated method stub
        return null;
    }

}

--EDIT:

found Workaround

Just to have some functional code i do now:

listview.setAdapter( new ReceiptListAdapter(activity,mcontext, -new dataset-);

Works, but not how it is supposed to work.

Answer 1

Change your method from

public void updateReceiptsList(List<Receipt> newlist) {
    receiptlist = newlist;
    this.notifyDataSetChanged();
}

To

public void updateReceiptsList(List<Receipt> newlist) {
    receiptlist.clear();
    receiptlist.addAll(newlist);
    this.notifyDataSetChanged();
}

So you keep the same object as your DataSet in your Adapter.

Answer 2

I have the same problem, and i realize that. When we create adapter and set it to listview, listview will point to object somewhere in memory which adapter hold, data in this object will show in listview.

adapter = new CustomAdapter(data);
listview.setadapter(adapter);

if we create an object for adapter with another data again and notifydatasetchanged():

adapter = new CustomAdapter(anotherdata);
adapter.notifyDataSetChanged();

this will do not affect to data in listview because the list is pointing to different object, this object does not know anything about new object in adapter, and notifyDataSetChanged() affect nothing. So we should change data in object and avoid to create a new object again for adapter

Answer 3

As I have already explained the reasons behind this issue and also how to handle it in a different answer thread Here. Still i am sharing the solution summary here.

One of the main reasons notifyDataSetChanged() won't work for you - is,

Your adapter loses reference to your list.

When creating and adding a new list to the Adapter. Always follow these guidelines:

1. Initialise the arrayList while declaring it globally.
2. Add the List to the adapter directly with out checking for null and empty values . Set the adapter to the list directly (don't check for any condition). Adapter guarantees you that wherever you make changes to the data of the arrayList it will take care of it, but never loose the reference.
3. Always modify the data in the arrayList itself (if your data is completely new than you can call adapter.clear() and arrayList.clear() before actually adding data to the list) but don't set the adapter i.e If the new data is populated in the arrayList than just adapter.notifyDataSetChanged()

Hope this helps.