Android MapFragment within a Fragment

问题

I found many threads related to adding a map fragment within a fragment. But they didn't help me solve my problem. Im trying to add a map fragment to a fragment. But Im getting Null pointer exception as below :

11-25 10:19:55.222    9101-9101/com.uma.mobile E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.uma.mobile, PID: 9101
java.lang.NullPointerException
        at com.uma.mobile.subview.ShopDetails.<init>(ShopDetails.java:122)
        at com.uma.mobile.activity.Shop.onCreateView(Shop.java:119)
        at android.app.Fragment.performCreateView(Fragment.java:1700)
        at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
        at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
        at android.app.BackStackRecord.run(BackStackRecord.java:684)
        at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
        at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
        at android.os.Handler.handleCallback(Handler.java:733)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4998)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
        at dalvik.system.NativeStart.main(Native Method)

where Shop.java extends Fragment and ShopDetails extends RelativeLayout which has mapFragement in it.

shop_details.xml :

<RelativeLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:id="@+id/mapTile"
            android:layout_marginTop="10dp"
            android:padding="10dp"
            android:background="@drawable/grey_gradient_rounded"
            android:layout_below="@+id/description">


            <RelativeLayout
                android:id="@+id/mapViewContainer"
                android:layout_width="100dp"
                android:layout_height="wrap_content"
                android:layout_alignTop="@+id/nearestLocation"
                android:layout_alignBottom="@+id/tapToView" />
                <!--<fragment xmlns:android="http://schemas.android.com/apk/res/android"-->
                    <!--android:id="@+id/mapView"-->
                    <!--android:layout_width="100dp"-->
                    <!--android:layout_height="wrap_content"-->
                    <!--android:name="com.google.android.gms.maps.MapFragment"/>-->

This is how I'm adding the map fragment

mapFragment = new MapFragment();
    FragmentTransaction transaction=  fm.findFragmentByTag("SHOPS").getChildFragmentManager().beginTransaction();
    transaction.add(R.id.mapViewContainer,mapFragment,"MAP_FRAG").commit();

This is the place where I get the exception:

try {

                    MapsInitializer.initialize(activity);
                    mapFragment.getMap().getUiSettings().setZoomControlsEnabled(false);
                    LatLng position = new LatLng(loc._latitude, loc._longitude);
                    MarkerOptions markerOptions = new MarkerOptions()
                            .position(position)
                            .icon(BitmapDescriptorFactory.fromResource(R.drawable.arrow_pin2x));
                    mapFragment.getMap().addMarker(markerOptions);
                    mapFragment.getMap().moveCamera(CameraUpdateFactory.newLatLngZoom(position, 14));
                } catch (GooglePlayServicesNotAvailableException e) {
                    e.printStackTrace();
                    fm.beginTransaction().hide(mapFragment).commit();
                }
                            .icon(BitmapDescriptorFactory.fromResource(R.drawable.arrow_pin2x));
                    map.addMarker(markerOptions);
                    map.moveCamera(CameraUpdateFactory.newLatLngZoom(position, 14));

in mapFragment.getMap().getUiSettings()

回答1:

you should use mapview in fragment it also support map v2. see this https://developers.google.com/maps/documentation/android/reference/com/google/android/gms/maps/MapView

try this it will work.

public class MyMapFragment extends Fragment {

    private MapView mMapView;
    private GoogleMap mMap;
    private Bundle mBundle;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View inflatedView = inflater.inflate(R.layout.map_fragment, container, false);

        try {
            MapsInitializer.initialize(getActivity());
        } catch (GooglePlayServicesNotAvailableException e) {
            // TODO handle this situation
        }

        mMapView = (MapView) inflatedView.findViewById(R.id.map);
        mMapView.onCreate(mBundle);
        setUpMapIfNeeded(inflatedView);

        return inflatedView;
    }

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

    private void setUpMapIfNeeded(View inflatedView) {
        if (mMap == null) {
            mMap = ((MapView) inflatedView.findViewById(R.id.map)).getMap();
            if (mMap != null) {
                setUpMap();
            }
        }
    }

    private void setUpMap() {
        mMap.addMarker(new MarkerOptions().position(new LatLng(0, 0)).title("Marker"));
    }

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

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

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

And here is the corresponding res/layout/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" >

    <com.google.android.gms.maps.MapView
        android:id="@+id/map"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</RelativeLayout>

You can omit the RelativeLayout (and move the xmlns declartion up to your new root element, in this case the com.google.android.gms.maps.MapView) if you have just one element in your layout like in this example.

来源：https://stackoverflow.com/questions/20198750/android-mapfragment-within-a-fragment