addOnScrollListener 的 RecyclerView onScrolled 方法不能只调用一次吗？

Question

背景:
我通过添加 addOnScrollListener 函数使用 RecyclerView 实现分页逻辑.

面临的问题:
当 RecyclerView 适配器以 dy 值为 0 加载时，会调用一次 onScrolled 方法.但是，当滚动列表到达其末尾时，onScrolled 方法不会被触发，而onScrollStateChanged 被正确触发.

HistoryAdapter(Context context, ArrayList<HistoryItem> items, RecyclerView recyclerView) {
        inflater = LayoutInflater.from(context);
        this.items = items;
        preferences = PreferenceManager.getDefaultSharedPreferences(context);
        this.context = context;
        this.recyclerView = recyclerView;

        final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();

        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                Timber.w("onScrolled.. %s", dy);

                if (dy > 0) {
                    totalItemCount = linearLayoutManager.getItemCount();
                    lastVisibleItem = linearLayoutManager.findLastVisibleItemPosition();
                    Timber.e("totalItemCount: %s", totalItemCount);
                    Timber.e("lastVisibleItem: %s", lastVisibleItem);

                    if (!isLoading && totalItemCount <= (lastVisibleItem + 1)) {

                        Timber.i("End reached...");
                        if (onLoadMoreListener != null) {
                            //Log.i(TAG, "Episodes Adapter: onLoadMore calling...");
                            onLoadMoreListener.onLoadMore();
                        }
                        isLoading = true;
                    }
                }
            }

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

            }
        });
    }

回收站：

private void setupRecycler() {
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
        recyclerView.setLayoutManager(linearLayoutManager);
        historyAdapter = new HistoryAdapter(getActivity(), historyItems, recyclerView);
        recyclerView.setAdapter(historyAdapter);
        historyAdapter.setClickListener(this);
        historyAdapter.setOnLoadMoreListener(this);
        historyAdapter.setErrorClickListener(this);
    }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:id="@+id/header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/medium_text_color_blue"
        android:padding="12dp">

        <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="start"
            android:text="#"
            android:textColor="@android:color/white"
            android:textStyle="bold" />

        <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="4.5"
            android:gravity="start"
            android:text="CLASS"
            android:textAllCaps="true"
            android:textColor="@android:color/white"
            android:textStyle="bold" />

        <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:gravity="center"
            android:text="Date"
            android:textAllCaps="true"
            android:textColor="@android:color/white"
            android:textStyle="bold" />

        <TextView
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:gravity="center"
            android:text="time"
            android:textAllCaps="true"
            android:textColor="@android:color/white"
            android:textStyle="bold" />
    </LinearLayout>

    <FrameLayout
        android:layout_below="@+id/header"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/no_reflection_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="gone"
            android:layout_gravity="center"
            android:text="No Reflection History found!" />

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/history_recycler"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </FrameLayout>
</RelativeLayout>

Answer 1

另一种方法是检查回收站是否可以垂直滚动(如果无法滚动)，则表明回收站已经到达底部.

尝试一下

recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
super.onScrollStateChanged(recyclerView, newState)

            if (!recyclerView.canScrollVertically(1)) {
                // Load more
            }
        }

}

`