MapView google maps NullPointerException?

Question

I'm trying create a How to get using MapView. I created a Fragment and a XML to use that. The problem is when I try open the MapView throws a NullPointerException but I can't undertand why.

How could I solve it ?

XML

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <com.google.android.gms.maps.MapView
        android:id="@+id/mapView"
        android:layout_width="match_parent"
        android:layout_height="160dp"
        android:layout_marginRight="10dp" />

</LinearLayout>

The Fragment

public class FormComoChegarEmpresa extends Fragment{
    MapView mapView;
    private GoogleMap googleMap;
    private final String TAG = getClass().getSimpleName() + "->";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ((CustomDrawerLayout)getActivity()).getSupportActionBar().hide();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.como_chegar_empresa, container, false);
        mapView = (MapView)view.findViewById(R.id.mapView);


        return  view;
    }

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

    private void setMapView() {
        try {
            MapsInitializer.initialize(getActivity().getApplicationContext());
        } catch (Exception e) {
            e.printStackTrace();
        }

        googleMap = mapView.getMap();
        // latitude and longitude
        double latitude = 17.385044;
        double longitude = 78.486671;

        // create marker
        MarkerOptions marker = new MarkerOptions().position(
                new LatLng(latitude, longitude)).title("Hello Maps");

        // Changing marker icon
        marker.icon(BitmapDescriptorFactory
                .defaultMarker(BitmapDescriptorFactory.HUE_ROSE));

        // adding marker
        googleMap.addMarker(marker);
        CameraPosition cameraPosition = new CameraPosition.Builder()
                .target(new LatLng(17.385044, 78.486671)).zoom(12).build();
        googleMap.animateCamera(CameraUpdateFactory
                .newCameraPosition(cameraPosition));

        // Perform any camera updates here
    }    

}

Exception

java.lang.NullPointerException
            at br.com.package.myapp.frags.FormComoChegarEmpresa.setMapView(FormComoChegarEmpresa.java:80)
            at br.com.package.myapp.frags.FormComoChegarEmpresa.onActivityCreated(FormComoChegarEmpresa.java:56)
            at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1794)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:967)
            at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
            at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
            at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
            at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:454)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:157)
            at android.app.ActivityThread.main(ActivityThread.java:5356)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
            at dalvik.system.NativeStart.main(Native Method)

Answer 1

I've faced the same issue with my first attempt at GoogleMap and MapView.

The issue is that when you init the map, it takes a short while to load (which it does in the background). When you obtain the instance from the MapView, the value of the GoogleMap is still null (not initialized).

You need to use OnMapLoadedCallback here. Add an instance of this callback to the googleMap right after googleMap = mapView.getMap();. The callback body has a function called onMapLoaded(), wherein you place the following code:

googleMap.addMarker(marker);
CameraPosition cameraPosition = new CameraPosition.Builder()
        .target(new LatLng(17.385044, 78.486671)).zoom(12).build();
googleMap.animateCamera(CameraUpdateFactory
        .newCameraPosition(cameraPosition));

and anything as the likes of 'googleMap.<member>'. I'm adding the edited code below for your ease.

private void setMapView() {

    try {
        MapsInitializer.initialize(getActivity().getApplicationContext());
    } catch (Exception e) {
        e.printStackTrace();
    }

    googleMap = mapView.getMap();

    googleMap.setOnMapLoadedCallback(new OnMapLoadedCallback()
    {
        @Override
        public void onMapLoaded()
        {
            // latitude and longitude
                double latitude = 17.385044;
                double longitude = 78.486671;

                // create marker
                MarkerOptions marker = new MarkerOptions().position(
                    new LatLng(latitude, longitude)).title("Hello Maps");

                // Changing marker icon
                marker.icon(BitmapDescriptorFactory
                        .defaultMarker(BitmapDescriptorFactory.HUE_ROSE));

                // adding marker
                googleMap.addMarker(marker);
                CameraPosition cameraPosition = new CameraPosition.Builder()
                        .target(new LatLng(17.385044, 78.486671)).zoom(12).build();
                googleMap.animateCamera(CameraUpdateFactory
                        .newCameraPosition(cameraPosition));

            // Perform any camera updates here

        }
    });
  }