RecyclerView onScrollListener -on Reverse Layout-

Question

我在 Android 应用程序上使用 RecyclerView。我想首先显示底部并从底部滚动到顶部。我可以做到，但我想添加滚动监听器，当滚动位置在顶部时我调用一个函数。

    chatRecycler = (RecyclerView) findViewById(R.id.chatRecycler);
    LinearLayoutManager layoutManager = new LinearLayoutManager(this);
    layoutManager.setReverseLayout(true);
    layoutManager.setStackFromEnd(true);
    chatRecycler.setLayoutManager(layoutManager);
    chatRecycler.setItemAnimator(new DefaultItemAnimator());

我试过了，但没用。此代码将函数调用到底部：

chatRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
            if (!recyclerView.canScrollVertically(1) && newState==RecyclerView.SCROLL_STATE_IDLE) {

                pageId++;
                chatDuoPresenter.getChatData(pageId);
            }
        }
    });

Edit: I'm still searching solution.

Answer 1

Solution:

@Override
public void initScrollListener() {

    chatRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);

            int visibleItemCount = layoutManager.getChildCount();
            int totalItemCount = layoutManager.getItemCount();
            int firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition();

            if ((visibleItemCount + firstVisibleItemPosition) >= totalItemCount && firstVisibleItemPosition >= 0) {

                pageId++;
                chatDuoPresenter.getChatData(pageId);
            }
        }
    });
}