SupportMapFragment's getMap() returns null

Question

I'm trying to create a SupportMapFragment dynamically and to put it in a FrameLayout container.

My issue is that mMapFragment.getMap() returns null...

Anybody can help?

CenterMapFragment.java

public class CenterMapFragment extends Fragment {

    private SupportMapFragment mMapFragment;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        return inflater.inflate(R.layout.center_map_fragment, container, false);
    }

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

        if (GooglePlayServicesUtil.isGooglePlayServicesAvailable(getActivity()) == ConnectionResult.SUCCESS) {
            setUpMapIfNeeded();
        }
    }


    private void setUpMapIfNeeded() {

        if (mMapFragment == null) {

            mMapFragment = SupportMapFragment.newInstance();
            FragmentTransaction fragmentTransaction =
                            getChildFragmentManager().beginTransaction();
            fragmentTransaction.replace(R.id.map, mMapFragment);
            fragmentTransaction.commit(); 

            setUpMap();
        }
    }

    private void setUpMap() {       

        GoogleMap map = mMapFragment.getMap();  

        // map is null!

    }

    @Override
    public void onResume()
    {
        super.onResume();
        setUpMapIfNeeded();     
    }
}

center_map_fragment.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <FrameLayout
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </FrameLayout>

    <Button
        android:id="@+id/btn_loc"
        android:layout_width="60dp"
        android:layout_height="50dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentRight="true"
        android:background="@drawable/locbtn" />

</RelativeLayout>

Answer 1

commit() on a FragmentTransaction does not perform its operations immediately. By the time you call setUpMap(), onCreateView() will not have been called on the SupportMapFragment, and hence there will not yet be a map.

One approach is to not use nested fragments, electing instead to have CenterMapFragment extend SupportMapFragment, in which case getMap() should work any time after onCreateView() (e.g., onActivityCreated()).

Answer 2

In the following link MapView is used as CommonsWare suggests in the last part of his comment:

http://ucla.jamesyxu.com/?p=287

public class MapFragment extends Fragment {

    MapView m;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
            Bundle savedInstanceState) {
        // inflat and return the layout
        View v = inflater.inflate(R.layout.map_fragment, container, false);
        m = (MapView) v.findViewById(R.id.mapView);
        m.onCreate(savedInstanceState);

        return v;
    }

    @Override
    public void onResume() {
        super.onResume();
        m.onResume();
    }

    @Override
    public void onPause() {
        super.onPause();
        m.onPause();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        m.onDestroy();
    }

    @Override
    public void onLowMemory() {
        super.onLowMemory();
        m.onLowMemory();
    }
}

I hope these will be helpful.