无法获取GoogleMap对象

我已经创建了MapFragment类。在这里,我创建了GoogleMap对象 googleMap = mMapView.getMap() 我有一个方法 分析器任务 如果我打电话 分析器任务 然后从该方法的onCreate 分析器任务 工作成功 googleMap.addPolyline(lineOptions) 作品但如果我调用方法 分析器任务 然后从另一个活动 googleMap.addPolyline(线条选项) 不起作用,它显示空指针异常。我想在这里 谷歌地图 无法获取MapView的实例。现在谁能给我一个建议吗?这样我就可以得到 谷歌地图 在里面 分析器任务 如果它是从另一个活动调用的。我在下面附上了我的代码:

public class MapFragment extends Fragment implements
        GoogleMap.OnInfoWindowClickListener{

    MapView mMapView;

    private static final int MAP_ZOOM_AMOUNT=17;
    private TextView locName;
    private TextView mapIndicator;
    private GoogleMap googleMap=null;
    private String locationName;
    private String mapIndicatorText;
    private int categoryId;
    private int locationNameId;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_map, container,
                false);
        mMapView = (MapView) rootView.findViewById(R.id.mapView);
        locName = (TextView) rootView.findViewById(R.id.tv_location_name);
        mapIndicator = (TextView) rootView.findViewById(R.id.tv_map_indicator);
        locName.setText(locationName);
        mapIndicator.setText(Html.fromHtml("সব " + mapIndicatorText + " এর স্থান ম্যাপ এ দেখানো হয়েছে"));
        mMapView.onCreate(savedInstanceState);
        mMapView.onResume();

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

        googleMap = mMapView.getMap();
        googleMap.setOnInfoWindowClickListener(this);

        return rootView;
    }
    @Override
    public void onInfoWindowClick(Marker marker) {
        LatLng loc = marker.getPosition();

    }


    private class ParserTask extends AsyncTask<String, Integer, List<List<HashMap<String,String>>> >{

        // Parsing the data in non-ui thread
        @Override
        protected List<List<HashMap<String, String>>> doInBackground(String... jsonData) {

            JSONObject jObject;
            List<List<HashMap<String, String>>> routes = null;

            try{
                jObject = new JSONObject(jsonData[0]);
                RouteActivity parser = new RouteActivity();

                // Starts parsing data
                routes = parser.parse(jObject);
            }catch(Exception e){
                e.printStackTrace();
            }
            return routes;
        }

        // Executes in UI thread, after the parsing process
        @Override
        protected void onPostExecute(List<List<HashMap<String, String>>> result) {

            ArrayList<LatLng> points = null;
            PolylineOptions lineOptions = null;

            // Traversing through all the routes
            for(int i=0;i<result.size();i++){
                points = new ArrayList<LatLng>();
                lineOptions = new PolylineOptions();

                // Fetching i-th route
                List<HashMap<String, String>> path = result.get(i);

                // Fetching all the points in i-th route
                for(int j=0;j<path.size();j++){
                    HashMap<String,String> point = path.get(j);

                    double lat = Double.parseDouble(point.get("lat"));
                    double lng = Double.parseDouble(point.get("lng"));
                    LatLng position = new LatLng(lat, lng);

                    points.add(position);
                }

                // Adding all the points in the route to LineOptions
                lineOptions.addAll(points);
                lineOptions.width(2);
                lineOptions.color(Color.RED);
            }
            //setUpMapIfNeeded();
            // Drawing polyline in the Google Map for the i-th route
            ***googleMap.addPolyline(lineOptions);***

        }
    }



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

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

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

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

}