android - 滚动顶部时的 Recycler View 应该加载数据

Question

我正在尝试制作一个聊天应用程序，其中服务器在用户滚动到顶部时仅获取并显示 15 条消息我想加载更多数据并将其附加到数组列表我尝试了 addonScroll 监听器但它仅在用户滚动到底部而不是顶部如果用户滚动到顶部我怎么能获得相同的功能

  public UserAdapter(RecyclerView recyclerView, Activity activity, ArrayList<User> arrayList) {
    this.activity = activity;
    this.arrayList = arrayList;
    final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {

        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

            super.onScrolled(recyclerView, dx, dy);
            totalItemCount = linearLayoutManager.getItemCount();
            lastItemCount = linearLayoutManager.findLastVisibleItemPosition();
            Log.d(TAG, "onScrolled: " + lastItemCount + " " + totalItemCount);
            if (!isLoading && totalItemCount <= (lastItemCount + visibleThreshold)) {
                if (iLoadMore != null) {
                    iLoadMore.onLoadMore();
                    isLoading = true;
                }
            }
        }
    });
}

我的主要 Activity

    adapter.setUnLoaded();
    adapter.setiLoadMore(new ILoadMore() {
        @Override
        public void onLoadMore() {
            arrayList.add(null);//for the progressbar
            adapter.notifyItemInserted(arrayList.size() - 1);
            Log.d("LOADMORE", "onLoadMore: scrolling working");
            BackgroundTask backgroundTask1 = new BackgroundTask(getApplicationContext());
            backgroundTask1.delegate = (BackgroundTask.AsynResponse) context;
            backgroundTask1.execute("getuser");
        }
    });

Answer 1

recyclerViewParticulars.addOnScrollListener(new RecyclerView.OnScrollListener() {

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                if (dy > 0 ) {
                    // Scrolling up
                    Log.d("recyclerviewscroll", "up");



                } else if(dy <0 ){
                    // Scrolling down
                    Log.d("recyclerviewscroll", "down");

                }
            }
}