java - 如何检测哪个 fragment 处于 Activity 状态？

Question

我的项目包括 tabLayout 内的 fragments。 Fragments 在 adapter 中有 recyclerView，可以从 Web 服务器加载数据。在本例中，我想为适配器使用两种不同的布局。我知道如何使用 StackOverflow 中的两种不同的布局，但我的问题是我必须检测必须加载哪个 fragment 。因此，我必须从 adapter 类中检测哪个 fragment 处于 Activity 状态。我怎样才能做到这一点？

VoyageAdapter.java

 public class VoyageAdapter extends RecyclerView.Adapter<VoyageAdapter.ViewHolder> {

@Override
public VoyageAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
if (Case_A){
  View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.row_voyage_view_bus, parent, false);
    return new ViewHolder(itemView);}

else if (Case_B){
   View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.row_voyage_view, parent, false);
    return new ViewHolder(itemView);
    }
}}

BusFragment.java

 public class BusFragment extends MyBaseFragment {
TabLayout tabLayout;
MyViewPager viewPager;
CustomFragmentPagerAdapter adapter;

public BusFragment() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_base_voyage, container, false);
    tabLayout = view.findViewById(R.id.tabLayout);
    viewPager = view.findViewById(R.id.viewPager);
    adapter = new CustomFragmentPagerAdapter(getChildFragmentManager());
    if (ResultActivity.hasReturn)
        attachFragmentsHasReturn();
    else
        attachFragmentsOneWay();
    return view;
}

void searchVoyages() {
    Voyage.getInstance().searchBusVoyages(getContext());
}

@Override
public void updateDate() {
    for (Fragment fragment :
            adapter.getFragments()) {
        ((MyBaseVoyageFragment) fragment).showLoadingDialog(true);
    }

    searchVoyages();
}
}

FlightFragment.java

 public class FlightFragment extends MyBaseFragment {
TabLayout tabLayout;
MyViewPager viewPager;
CustomFragmentPagerAdapter adapter;
public FlightFragment() {
    // Required empty public constructor
}
void searchVoyages(){
    Voyage.getInstance().searchFlightVoyages(getContext());
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_base_voyage, container, false);
    tabLayout = view.findViewById(R.id.tabLayout);
    viewPager =  view.findViewById(R.id.viewPager);
    adapter = new CustomFragmentPagerAdapter(getChildFragmentManager());
    if(ResultActivity.hasReturn)
        attachFragmentsHasReturn();
    else
        attachFragmentsOneWay();
    return view;
}
@Override
public void updateDate() {
    for (Fragment fragment:
            adapter.getFragments()) {
        ((MyBaseVoyageFragment)fragment).showLoadingDialog(true);
    }
    searchVoyages();
}
}

Answer 1

您可以尝试以下操作来获取当前 fragment :

Fragment currentFragment = adapter.getItem(viewPager.getCurrentItem());