java - RecyclerView.OnScrollListener 的问题

Question

向相反方向滚动不起作用。

我明白我错了只是通过Presenter重新更新View中的数据，并且必须它们都可用RecyclerView

当加载下一部分数据时，RecyclerView没有时间显示最后一个元素，并立即加载新的部分。

我做错了什么？

public class HomeActivity extends AppCompatActivity implements HomeView{


    @BindView(R.id.recyclerView)
    RecyclerView recyclerView;

    HomePresenter presenter;

    private static int offset;

    private static boolean isLoading;

    public static void setIsLoading(boolean isLoading) {
        HomeActivity.isLoading = isLoading;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);
        ButterKnife.bind(this);

        presenter = new HomePresenter(this);
        presenter.getData(offset);
        offset = 0;
        isLoading = true;
    }


    @Override
    public void setData(List<PokemonData.Pokemon> pokemons) {
        RecyclerViewHomeAdapter homeAdapter = new RecyclerViewHomeAdapter(pokemons, this);
        recyclerView.setAdapter(homeAdapter);
        GridLayoutManager layoutManager = new GridLayoutManager(this, 2, RecyclerView.VERTICAL, false);
        recyclerView.setLayoutManager(layoutManager);


        recyclerView.addOnScrollListener(new RecyclerViewOnScroll() {
            @Override
            protected void loadMore() {

                if (isLoading) {
                    isLoading = false;
                    offset+=30;
                    presenter.getData(offset);
                }
            }
        });
        homeAdapter.notifyDataSetChanged();

演讲者:

    void getData(int offset) {

            Call<PokemonData> pokemonDataCall = Utils.getApi().getData(offset, 30);

            pokemonDataCall.enqueue(new Callback<PokemonData>() {
                @Override
                public void onResponse(Call<PokemonData> call, Response<PokemonData> response) {

                    HomeActivity.setIsLoading(true);

                    if (response.isSuccessful() && response.body() != null) {
                        view.setData(response.body().getResults());
                    }
                    else {
                        view.onErrorLoading(response.message());
                    }
                }

                @Override
                public void onFailure(Call<PokemonData> call, Throwable t) {
                    HomeActivity.setIsLoading(true);
                    view.onErrorLoading(t.getLocalizedMessage());
                }
            });
        }

RecyclerViewOnScroll:

public abstract class RecyclerViewOnScroll extends RecyclerView.OnScrollListener {

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

        if ( dy > 0) {

            GridLayoutManager gridLayoutManager = (GridLayoutManager) recyclerView.getLayoutManager();
            int visibleItemCount = gridLayoutManager.getChildCount();
            int totalItemCount = gridLayoutManager.getItemCount();
            int firstVisibleItems = gridLayoutManager.findFirstVisibleItemPosition();

            if ((visibleItemCount + firstVisibleItems) >= totalItemCount) {
                loadMore();
            }
        }
    }

    protected abstract void loadMore();

Answer 1

试试这个

private Boolean mIsMoreLoading = false;
private Boolean mIsLastPage = false;


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

        if ( dy > 0) {

            GridLayoutManager gridLayoutManager = (GridLayoutManager) recyclerView.getLayoutManager();
            int visibleItemCount = gridLayoutManager.getChildCount();
            int totalItemCount = gridLayoutManager.getItemCount();
            int firstVisibleItems = gridLayoutManager.findFirstVisibleItemPosition();

            if ((!mIsMoreLoading) && (!mIsLastPage)) {
                    if ((firstVisibleItems + visibleItemCount) >= totalItemCount
                            && firstVisibleItems >= 0
                            && totalItemCount >= 20 //  the items in one request) {
                        loadMore()
                        mIsMoreLoading = true
                    }
                }
        }
    }