Разбивка на страницы с помощью staggeredGridLayoutManager и recyclerView

Question

Здравствуйте, мне нужно сделать бесконечную прокрутку (разбиение на страницы) с помощью просмотрщика, используя staggeredGridLayoutManager. Нумерация страниц работает, но проблема в том, что onLoadMore() функция вызывается так много раз во время прокрутки, что вызывает проблемы, вот мой код:

 newSearchAdapter = new NewSearchAdapter(getActivity(), gridData);
            StaggeredGridLayoutManager mLayoutManager;
            mLayoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);
            mLayoutManager.setGapStrategy(StaggeredGridLayoutManager.GAP_HANDLING_NONE);
            rv_NewProfilesGrid.setLayoutManager(mLayoutManager);
            rv_NewProfilesGrid.setAdapter(newSearchAdapter);
            rv_NewProfilesGrid.addOnScrollListener(new EndlessRecyclerOnScrollListenerStaggeredLayoutmanager(mLayoutManager) {
                @Override
                public void onLoadMore(int current_page) {

                  //calling the api

                }
            });

и вот мой список прокрутки

Я думаю, что проблема здесь с getFirstVisibleItems() функция, потому что с GridLayoutManger или LinearLayoutManager возвращает целое число, а с StaggeredLayout возвращает массив int, поэтому я сделал следующее:

public abstract class EndlessRecyclerOnScrollListenerStaggeredLayoutmanager extends RecyclerView.OnScrollListener {
    public static String TAG = EndlessRecyclerOnScrollListenerStaggeredLayoutmanager.class.getSimpleName();
    private int scrolledDistance = 0;
    private boolean controlsVisible = false;

    private boolean loading = true; // True if we are still waiting for the last set of data to load.
    private int visibleThreshold = 5; // The minimum amount of items to have below your current scroll position before loading more.
    public static boolean  loadOneTime = false;
    private int pastVisibleItems, visibleItemCount, totalItemCount,previousTotal;

    private int current_page = 1;

    private StaggeredGridLayoutManager mStaggeredGridLayoutManager;

    public EndlessRecyclerOnScrollListenerStaggeredLayoutmanager(StaggeredGridLayoutManager staggeredGridLayoutManager) {
        this.mStaggeredGridLayoutManager = staggeredGridLayoutManager;

    }


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

        visibleItemCount = recyclerView.getChildCount();
        totalItemCount = mStaggeredGridLayoutManager.getItemCount();

        int[] firstVisibleItems = null;
        firstVisibleItems = mStaggeredGridLayoutManager.findFirstVisibleItemPositions(firstVisibleItems);
        if (firstVisibleItems != null && firstVisibleItems.length > 0) {
            pastVisibleItems = firstVisibleItems[0];
        }


        if (loading) {
            if ((visibleItemCount + pastVisibleItems) >= totalItemCount) {
                loading = false;

                previousTotal = totalItemCount;
            }
        }
        if (!loading && (totalItemCount - visibleItemCount)
                <= (pastVisibleItems + visibleThreshold)) {
            // End has been reached

            // Do something
            current_page++;
            loadOneTime=false;
            onLoadMore(current_page);

            loading = true;
        }

        if (scrolledDistance > 1 && controlsVisible) {
            controlsVisible = false;
            scrolledDistance = 0;
        } else if (scrolledDistance < -1 && !controlsVisible) {
            controlsVisible = true;
            scrolledDistance = 0;
        }

        if ((controlsVisible && dy > 0) || (!controlsVisible && dy < 0)) {
            scrolledDistance += dy;
        }
    }

    public abstract void onLoadMore(int current_page);


}

Answer 1

Попробуй это. Я позаимствовал его из ответа о переполнении стека и позаимствовал другой ответ и объединил их, я наконец решил его.

import android.util.Log
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.recyclerview.widget.StaggeredGridLayoutManager

abstract class PaginationScrollListener constructor() :
    RecyclerView.OnScrollListener() {

    private lateinit var mLayoutManager: RecyclerView.LayoutManager

    constructor(layoutManager: GridLayoutManager) : this() {
        this.mLayoutManager = layoutManager
    }

    constructor(layoutManager: StaggeredGridLayoutManager) : this() {
        this.mLayoutManager = layoutManager
    }

    constructor(layoutManager: LinearLayoutManager) : this() {
        this.mLayoutManager = layoutManager
    }


    /*
     Method gets callback when user scroll the search list
     */
    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        val visibleItemCount = mLayoutManager.childCount
        val totalItemCount = mLayoutManager.itemCount
        var firstVisibleItemPosition = 0

        when (mLayoutManager) {
            is StaggeredGridLayoutManager -> {
                val firstVisibleItemPositions =
                    (mLayoutManager as StaggeredGridLayoutManager).findFirstVisibleItemPositions(null)
                // get maximum element within the list
                firstVisibleItemPosition = firstVisibleItemPositions[0]
            }
            is GridLayoutManager -> {
                firstVisibleItemPosition =
                    (mLayoutManager as GridLayoutManager).findFirstVisibleItemPosition()
            }
            is LinearLayoutManager -> {
                firstVisibleItemPosition =
                    (mLayoutManager as LinearLayoutManager).findFirstVisibleItemPosition()
            }
        }
        if (!isLoading && !isLastPage) {
            if (visibleItemCount + firstVisibleItemPosition >= totalItemCount
                && firstVisibleItemPosition >= 0
            ) {
                Log.i(TAG, "Loading more items")
                loadMoreItems()
            }
        }
    }

    protected abstract fun loadMoreItems()

    abstract val isLastPage: Boolean
    abstract val isLoading: Boolean

    companion object {
        private val TAG = PaginationScrollListener::class.java.simpleName
    }
}

И используйте это в своем представлении ресайклера таким образом

rvCategoryProducts.addOnScrollListener(object :
            PaginationScrollListener(layoutManager) {
            override fun loadMoreItems() {
                vm.isLoading = true
                vm.currentPage++

                GlobalScope.launch {
                    vm.getCategoryProductByCatId(vm.id, vm.currentPage)
                }
            }

            override val isLastPage: Boolean
                get() = vm.isLastPage
            override val isLoading: Boolean
                get() = vm.isLoading
        })