@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
      if (viewType == VIEW_TYPE_ITEM) {
          View view = LayoutInflater.from(activity).inflate(R.layout.list_contact, parent, false);
          return new UserViewHolder(view);
      } else if (viewType == VIEW_TYPE_LOADING) {
          View view = LayoutInflater.from(activity).inflate(R.layout.item_loading, parent, false);
          return new LoadingViewHolder(view);
      }
      return null;
}