viewholder6.java

@NonNull
@Override
public View getView(int position, @Nullable View convertView, 
                    @NonNull ViewGroup parent) {
    if (convertView == null) {
        convertView = LayoutInflater.from(getContext())
                .inflate(R.layout.contact_item, parent, false);
    }

    Contact contact = contacts.get(position);
    ((TextView)convertView
            .findViewById(R.id.name_text_view))
            .setText(contact.getName());
    ((TextView)convertView
            .findViewById(R.id.mobile_text_view))
            .setText(contact.getMobile());
    ((TextView)convertView
            .findViewById(R.id.landline_text_view))
            .setText(contact.getLandline());

    return convertView;
}