Update data in Arrayadapter

This is how I update the Adapter with new data:

            if (arrayAdapter == null) {
                arrayAdapter = new CustomArrayAdapter(getActivity(), data);
                listview.setAdapter(userAutoCompleteAdapter);
            } else {
                arrayAdapter.clear();
                arrayAdapter.addAll(newData);
                arrayAdapter.notifyDataSetChanged();
            }

Assuming the getNewData() function returns ArrayList<CustomItem>, can you change the line:

items=getNewData();

to

items.addAll(getNewData());

and see if that works?