带有Viewpager和底部导航的嵌套片段

Question

我被嵌套的片段困住了，有人请指导我一点。我处于学习阶段...

实际上，我正在使用bottomNavigationView和popluate片段，并且在选择一项时，其中一个片段具有视图分页器和选项卡布局，并从火力基地加载列表数据。问题是，当选择其中包含viewpager的片段时，数据会成功获取，但不会在列表视图中填充，但是当我查看视图页面时，就会填充listview。任何人都可以帮助我解决这个问题，或指导我将网络呼叫分散放置在哪里或其他解决方案。

第一个具有Viewpager的片段。

public class explore extends Fragment {

public static explore Instance = null;
private TabLayout tabLayout;
private ViewPager viewPager;
private Activity activity;
private Context context;
private PagerAdapter pagerAdapter;

public static explore getInstance() {
    if (Instance == null) {
        Instance = new explore();
    }
    return Instance;
}

public explore() {
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    activity = (Activity) getActivity();
    context = getActivity();
    return inflater.inflate(R.layout.fragment_explore, container, false);
}

@Override
public void onViewCreated(@NonNull View v, @Nullable Bundle savedInstanceState) {
    tabLayout = v.findViewById(R.id.tabs_Explore);
    viewPager = v.findViewById(R.id.viewpager_Explore);
    tabLayout.setupWithViewPager(viewPager);
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    List<Category> categories = new FirebaseHelper(getActivity()).getCategoriesList();
    pagerAdapter = new PagerAdapter(getChildFragmentManager(), categories);
    viewPager.setAdapter(pagerAdapter);
    super.onActivityCreated(savedInstanceState);
}

}

寻呼机的第一个片段是（ChildFragment）

public class categories extends Fragment {

private static categories Obj = null;


private RecyclerView listView;

private List<Category> categoryList;

private CategoryAdapter categoryAdapter;


public categories() {
    categoryList = new ArrayList<>();
}

public static categories getInstance() {
    if (Obj == null) {
        Obj = new categories();
    }
    return Obj;
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View v = inflater.inflate(R.layout.fragment_blank, container, false);
    listView = v.findViewById(R.id.mRecycler);
    listView.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
    listView.setHasFixedSize(true);
    SnapHelper helper = new LinearSnapHelper();
    helper.attachToRecyclerView(listView);
    categoryAdapter = new CategoryAdapter(getActivity(), categoryList);
    listView.setAdapter(categoryAdapter);


    return v;
}

@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
    Bundle bundle = getArguments();
    if (bundle != null) {
        categoryList = bundle.getParcelableArrayList("data");
        categoryAdapter.notifyDataSetChanged();

    }
    super.onActivityCreated(savedInstanceState);
}

}