مشکل در افزودن آیتم به RecyclerView

 سلام
من میخوام آیتم های جدید به لیست RecyclerView اضافه کنم.
و مشکلم اینه که میخوام این آیتم ها رو در رویداد OnScrollListener به لیستم اضافه کنم. ممنون میشم راهنمایی کنید.
این کد RecyclerView به همراه رویداد OnScrollListener هست :

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        Bundle args = getArguments();
        int tabPosition = args.getInt(TAB_POSITION);
        final String current_page = args.getString("cpage");
        final String last_page = args.getString("lpage");
        ArrayList<String> prs = args.getStringArrayList("prs");

        View v =  inflater.inflate(R.layout.fragment_list_view, container, false);
        RecyclerView recyclerView = (RecyclerView)v.findViewById(R.id.recyclerview);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        recyclerView.setAdapter(new DesignDemoRecyclerAdapter(prs));
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
        recyclerView.setLayoutManager(linearLayoutManager);
        EndlessRecyclerViewScrollListener scrollListener = new EndlessRecyclerViewScrollListener(linearLayoutManager) {
            @Override
            public void onLoadMore(final int page, int totalItemsCount, final RecyclerView view) {
                final int next = page + 1;
                final int last = Integer.parseInt(last_page);
                if(next <= last){
                    // Volley request for next page
                    assert ((MainActivity)getActivity()) != null;
                    ((MainActivity)getActivity()).volleyRequest(new VolleyCallback(){ // Request for Products
                        @Override
                        public void onSuccess(String result) {
                            //showMessage(result, 't');
                            try {
                                JSONObject obj = new JSONObject(result);
                                JSONArray products = obj.getJSONArray("data");

                            } catch (SecurityException | JSONException e) {
                                e.printStackTrace();
                            }

                        }

                        @Override
                        public void onFailed(String result) {
                            Toast.makeText(((MainActivity)getActivity()), result,
                                    Toast.LENGTH_LONG).show();
                        }
                    },"getproducts?page=" + page);
                }
                // Triggered only when new data needs to be appended to the list
                // Add whatever code is needed to append new items to the bottom of the list
                Toast.makeText(getActivity(),"Loading ...  Next page is " + next,Toast.LENGTH_SHORT).show();
            }
        };
        // Adds the scroll listener to RecyclerView
        recyclerView.addOnScrollListener(scrollListener);
        return v;
  }