Updating a Fragment View

Question

I need to update a Fragment View so that I can update my Recycle View as values come in from my database in real time. I currently do this in the OnCreateView method but this does not allow me to update when the tabs are switched.

public class UserFragment extends Fragment {

public UserFragment() {
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View rootView = inflater.inflate(R.layout.fragment_blank, container, false);

    RecyclerView rv = (RecyclerView) rootView.findViewById(R.id.rv_recycler_view);
    rv.setHasFixedSize(false);
    final ArrayList<widgetData> dummie_list = new ArrayList<>();
    FirebaseAuth mAuth = FirebaseAuth.getInstance();
    final MyAdapter adapter = new MyAdapter(dummie_list);
    rv.setAdapter(adapter);

    DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("contacts").child(mAuth.getUid());
    ref.addListenerForSingleValueEvent(
            new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    for(DataSnapshot ds: dataSnapshot.getChildren())
                    {
                        if(!dummie_list.contains(new widgetData(ds.getValue(String.class), "FUCK FIREBASE", 0)))
                        {
                            dummie_list.add(new widgetData(ds.getValue(String.class), "FUCK FIREBASE", 0));
                            adapter.notifyDataSetChanged();

                        }
                    }
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {
                    //handle databaseError
                }
            });

    LinearLayoutManager llm = new LinearLayoutManager(getActivity());
    rv.setLayoutManager(llm);

    return rootView;
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    if (isVisibleToUser) {
        //Update view here
    }
}

}

The setUserVisibleHint is what is causing problems as it seems there is no way to update the view since I don't have access to the parameters that the OnCreateView gets.

score 0 · Answer 1 · answered Nov 12 '17 at 07:58

You are using ViewPager .So add a PageChange Listener to pager and give callback to each fragment you want to update .

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {

// optional 
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { }

// optional 
@Override
public void onPageSelected(int position) {
 // Call a callback here to fragment to initialize update
      }

// optional 
@Override
public void onPageScrollStateChanged(int state) { }

});

Or you can use EventBus to trigger update on any other event .

Updating a Fragment View

1 Answers1