El fragmento es nulo al usar el FragmentStatePagerAdapter

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Tengo 3 pestañas de navegación inferiores en mi aplicación

  • Inicio
  • MyTour
  • Perfil

En MyTour, estoy usando MyTourFragmentque tienen 3 pestañas diferentes

  • Pendiente(0)
  • Éxito(1)
  • Fallido(2)

Para las tres pestañas (Pendiente, Éxito, Fallido) estoy usando FragmentMyTourJobListy dependo de la condición de que muestre datos pendientes o de éxito o fallidos en las tres pestañas.

Declaración del problema:

Cuando hago clic en MyTourel elemento de navegación, la instancia de fragmento pendiente se anula y sólo puedo ver el fragmento en blanco, pero si hago clic en éxito o fracaso, entonces puedo ver los datos. Los datos de las pestañas pendientes sólo son visibles después de volver de otras pestañas, pero no inicialmente.

Aquí está el código de MyTourFragment :

public class MyTourFragment {

public MyTourFragment() {

}

public static MyTourFragment newInstance(MyTourFragmentListener myTourFragmentListener) {
    return new MyTourFragment(myTourFragmentListener);
}

private MyTourFragment(MyTourFragmentListener myTourFragmentListener) {
    this.mMyTourFragmentListener = myTourFragmentListener;
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mViewModel.setNavigator(this);
    setHasOptionsMenu(true);

    //Get the Tab Id.
    Bundle bundle = this.getArguments();
    if (bundle != null) {
        mViewModel.setSelectedDateTimeMillis(bundle.getLong(todaysDateForMyTour, Calendar.getInstance().getTimeInMillis()));
        mSelectedTabId = bundle.getInt(KEY_SELECTED_TAB, 0);
    }

    mMyTourJobsListPagerAdapter = new MyTourJobsListPagerAdapter(this, mViewModel.getTourIdForSelectedDate(), this);

}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    mFragmentMyTourBinding = getViewDataBinding();

    mFragmentMyTourBinding.vpMyTour.setOffscreenPageLimit(2);
    mFragmentMyTourBinding.vpMyTour.setCurrentItem(0);
    mFragmentMyTourBinding.vpMyTour.setAdapter(mMyTourJobsListPagerAdapter);
    mFragmentMyTourBinding.tabLayoutMyTour.setupWithViewPager(mFragmentMyTourBinding.vpMyTour, true);
    mFragmentMyTourBinding.tabLayoutMyTour.addOnTabSelectedListener(this);

    setUpTabs();
}

private void setUpTabs() {

    //Select the current Tab.
    mFragmentMyTourBinding.vpMyTour.setCurrentItem(mSelectedTabId);

    //Refresh job list as per the selected date.
    FragmentMyTourJobsList fragmentMyTourJobsList = mMyTourJobsListPagerAdapter.getFragmentAtTab(mSelectedTabId); **// this is null first time**
    if (fragmentMyTourJobsList != null) {
        fragmentMyTourJobsList.refreshJobsList(mViewModel.getTourIdForSelectedDate());
    } 
}

}

Aquí está el código del adaptador de MyTourJobsListPager :

public class MyTourJobsListPagerAdapter extends FragmentStatePagerAdapter {

private static final int MY_TOUR_JOBS_LIST_PAGES_COUNT = 3;
private static final int POSITION_TAB_PENDING = 0;
private static final int POSITION_TAB_SUCCESS = 1;
private static final int POSITION_TAB_FAILED = 2;
private HashMap<Integer, FragmentMyTourJobsList> mTabsFragments = new HashMap<Integer, FragmentMyTourJobsList>();
private long mTourId;
private FragmentMyTourJobsList.FragmentMyTourJobsListListener mFragmentMyTourJobsListListener;

public MyTourJobsListPagerAdapter(Fragment fragment, long tourId, FragmentMyTourJobsList.FragmentMyTourJobsListListener fragmentMyTourJobsListListener) {
    super(fragment.getChildFragmentManager(), BEHAVIOR_RESUME_ONLY_CURRENT_FRAGMENT);
    this.mTourId = tourId;
    this.mFragmentMyTourJobsListListener = fragmentMyTourJobsListListener;
}

public void setTourId(long tourId) {
    this.mTourId = tourId;
}

@Override
public int getCount() {
    return MY_TOUR_JOBS_LIST_PAGES_COUNT;
}

@NonNull
@Override
public Object instantiateItem(@NonNull ViewGroup container, int position) {
    Fragment fragment = (Fragment) super.instantiateItem(container, position);
    mTabsFragments.put(position, (FragmentMyTourJobsList) fragment);
    return fragment;
}


@Override
public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
    mTabsFragments.remove(position);
    super.destroyItem(container, position, object);
}

@Override
public Fragment getItem(int position) {
    FragmentMyTourJobsList fragmentMyTourJobsList;
    switch (position) {
        case POSITION_TAB_SUCCESS:
            fragmentMyTourJobsList = getFragmentWithBundle(Constants.JOB_STATUS_SUCCESSFUL);
            break;
        case POSITION_TAB_FAILED:
            fragmentMyTourJobsList = getFragmentWithBundle(Constants.JOB_STATUS_FAILED);
            break;
        case POSITION_TAB_PENDING:
        default:
            fragmentMyTourJobsList = getFragmentWithBundle(Constants.JOB_STATUS_ACCEPTED);
            break;

    }
    return fragmentMyTourJobsList;
}

public FragmentMyTourJobsList getFragmentAtTab(int tabPosition) {
    return mTabsFragments.get(tabPosition);
}

private FragmentMyTourJobsList getFragmentWithBundle(String jobsStatus) {
    FragmentMyTourJobsList fragmentToLoad = FragmentMyTourJobsList.newInstance();

    Bundle bundle = new Bundle();
    bundle.putString(FragmentMyTourJobsList.KEY_ARG_JOBS_STATUS, jobsStatus);
    bundle.putLong(FragmentMyTourJobsList.KEY_ARG_TOUR_ID, mTourId);
    bundle.putSerializable(FragmentMyTourJobsList.KEY_ARG_FRAGMENT_MY_TOUR_JOBS_LIST_LISTENER, mFragmentMyTourJobsListListener);

    fragmentToLoad.setArguments(bundle);

    return fragmentToLoad;
}

}

Todo está funcionando, pero cuando voy a la pestaña de pendientes la primera vez, entonces no funciona. ¿Me estoy perdiendo algo aquí?

Añadido FragmentMytourJobList

public class FragmentMyTourJobsList extends BaseFragment<FragmentMyTourJobsListBinding, MyTourJobsListViewModel> implements MyTourJobsListNavigator {

public static FragmentMyTourJobsList newInstance() {
    return new FragmentMyTourJobsList();
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mViewModel.setNavigator(this);

    Bundle bundle = this.getArguments();
    if (bundle != null) {
        mJobsStatus = bundle.getString(KEY_ARG_JOBS_STATUS);
        mTourId = bundle.getLong(KEY_ARG_TOUR_ID, 0);
    }
}

@Override
public int getBindingVariable() {
    return myTourJobsListViewModel;
}

@Override
public int getLayoutId() {
    return R.layout.fragment_my_tour_jobs_list;
}

@Override
public MyTourJobsListViewModel getViewModel() {
    mViewModel = ViewModelProviders.of(this, new ViewModelProviderFactory(Objects.requireNonNull(getActivity()).getApplication())).get(MyTourJobsListViewModel.class);
    return mViewModel;
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    mFragmentMyTourJobsListBinding = getViewDataBinding();

    // fetch job list  from database
    ArrayList<JobUiModel> jobList = mViewModel.fetchJobs(mTourId, mJobsStatus);
    RecyclerView.LayoutManager rvLayoutManager = new LinearLayoutManager(getActivity());
    mFragmentMyTourJobsListBinding.rvMyTourJobs.setLayoutManager(rvLayoutManager);

    // initialize adapter
    mJobsListAdapter = new MyTourJobsListAdapter(getContext(), jobList, mJobsStatus);
    mFragmentMyTourJobsListBinding.rvMyTourJobs.setAdapter(mJobsListAdapter);
    mJobsListAdapter.setClickInterface(this);

    mFragmentMyTourJobsListBinding.rvMyTourJobs.addItemDecoration(new EndOffsetItemDecoration(CommonUtils.dpToPx(56)));
}

void refreshJobsList(long tourId) {

    if (tourId > 0) {
        mTourId = tourId;
        mViewModel.fetchJobs(tourId, mJobsStatus);
        // fetch job list  from database
        ArrayList<JobUiModel> jobList = mViewModel.fetchJobs(mTourId, mJobsStatus);
        mJobsListAdapter.setDataset(jobList);
        mJobsListAdapter.notifyDataSetChanged();


    } else {
        mJobsListAdapter.setDataset(null);
        mJobsListAdapter.notifyDataSetChanged();

    }
}

}

Publicado el 24/05/2020 a las 14:06
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