ListView appears in one shot whereas I would like to appear on the fly

Question

The app works ok, but computing each listview entry takes some time (I'm doing a ping on network devices) so I'm looking for creating entries on the fly. Although I google for a solution, I'm lost: I can't find where I need to modify my code.

Also I'd like to have a textview or a progressbar to indicate the progress but all the computing is taken by the listview and I only get that ino at the end. Explanations or a tutorial would be much appreciated on these problems.

listIPitem = new ArrayList<>();

iPadaptater = new IPadaptater(getActivity(), listIPitem);
ListView list_ip = (ListView) rootView.findViewById(id.listIP);
list_ip.setAdapter(iPadaptater);
DiscoverNetwork dn = new DiscoverNetwork();
dn.passContext(context, listIPitem, iPadaptater)

Here is my adaptater:

public class IPadaptater extends BaseAdapter {

    private List<IPitem> listIPitem;
    private LayoutInflater layoutInflater;
    Context context;

    public IPadaptater(Context c, List<IPitem> objects) {
        context = c;
        listIPitem = objects;
        layoutInflater = LayoutInflater.from(context);
    }

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

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

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

    private class ViewIPHolder {
        TextView ip_disc;
    }

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

        if(convertView == null) {
            viewHolder = new ViewIPHolder();

            convertView = layoutInflater.inflate(R.layout.listview_item_discovery, null);

            viewHolder.ip_disc = (TextView) convertView.findViewById(R.id.ip_disc);

            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewIPHolder) convertView.getTag();
        }
        viewHolder.ip_disc.setText(listIPitem.get(position).getIPaddress());

        notifyDataSetChanged();

        return convertView;
    }

}

And here is where I process my data:

   listIPitem.clear();


    for(int i=1;i<50;i++) {

        IPitem iPitem = new IPitem();
        ip = network + i;
        if(!ping(ip)) continue;
        iPitem.setIPaddress(ip);
        listIPitem.add(iPitem);
        iPadaptater.notifyDataSetChanged();
    }