GoogleMap.OnMyLocationChangeListener 抛出 NullPointerException

Question

我正在尝试在 GoogleMap 中创建一个方向，以创建一个如何进入我的 MapView 以显示路线源 -> 目标，为此我正在尝试实现一个 GoogleMap.OnMyLocationChangeListener 但总是抛出NullPointerException 在此代码中 map.getMyLocation().getLatitude();

我该怎么做？

public class GMapV2Direction {
    public final static String MODE_DRIVING = "driving";
    public final static String MODE_WALKING = "walking";

    public GMapV2Direction() {
    }

    public Document getDocument(LatLng start, LatLng end, String mode) {
        String url = "http://maps.googleapis.com/maps/api/directions/xml?"
                + "origin=" + start.latitude + "," + start.longitude
                + "&destination=" + end.latitude + "," + end.longitude
                + "&sensor=false&units=metric&mode=driving";
        Log.d("url", url);
        try {
            HttpClient httpClient = new DefaultHttpClient();
            HttpContext localContext = new BasicHttpContext();
            HttpPost httpPost = new HttpPost(url);
            HttpResponse response = httpClient.execute(httpPost, localContext);
            InputStream in = response.getEntity().getContent();
            DocumentBuilder builder = DocumentBuilderFactory.newInstance()
                    .newDocumentBuilder();
            Document doc = builder.parse(in);
            return doc;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public String getDurationText(Document doc) {
        try {

            NodeList nl1 = doc.getElementsByTagName("duration");
            Node node1 = nl1.item(0);
            NodeList nl2 = node1.getChildNodes();
            Node node2 = nl2.item(getNodeIndex(nl2, "text"));
            Log.i("DurationText", node2.getTextContent());
            return node2.getTextContent();
        } catch (Exception e) {
            return "0";
        }
    }

    public int getDurationValue(Document doc) {
        try {
            NodeList nl1 = doc.getElementsByTagName("duration");
            Node node1 = nl1.item(0);
            NodeList nl2 = node1.getChildNodes();
            Node node2 = nl2.item(getNodeIndex(nl2, "value"));
            Log.i("DurationValue", node2.getTextContent());
            return Integer.parseInt(node2.getTextContent());
        } catch (Exception e) {
            return -1;
        }
    }

    public String getDistanceText(Document doc) {   
        try {
            NodeList nl1;
            nl1 = doc.getElementsByTagName("distance");

            Node node1 = nl1.item(nl1.getLength() - 1);
            NodeList nl2 = null;
            nl2 = node1.getChildNodes();
            Node node2 = nl2.item(getNodeIndex(nl2, "value"));
            Log.d("DistanceText", node2.getTextContent());
            return node2.getTextContent();
        } catch (Exception e) {
            return "-1";
        }
    }

    public int getDistanceValue(Document doc) {
        try {
            NodeList nl1 = doc.getElementsByTagName("distance");
            Node node1 = null;
            node1 = nl1.item(nl1.getLength() - 1);
            NodeList nl2 = node1.getChildNodes();
            Node node2 = nl2.item(getNodeIndex(nl2, "value"));
            Log.i("DistanceValue", node2.getTextContent());
            return Integer.parseInt(node2.getTextContent());
        } catch (Exception e) {
            return -1;
        }   
    }

    public String getStartAddress(Document doc) {
        try {
            NodeList nl1 = doc.getElementsByTagName("start_address");
            Node node1 = nl1.item(0);
            Log.i("StartAddress", node1.getTextContent());
            return node1.getTextContent();
        } catch (Exception e) {
            return "-1";
        }

    }

    public String getEndAddress(Document doc) {
        try {
            NodeList nl1 = doc.getElementsByTagName("end_address");
            Node node1 = nl1.item(0);
            Log.i("StartAddress", node1.getTextContent());
            return node1.getTextContent();
        } catch (Exception e) {
            return "-1";
        }
    }

    public String getCopyRights(Document doc) {
        try {
            NodeList nl1 = doc.getElementsByTagName("copyrights");
            Node node1 = nl1.item(0);
            Log.i("CopyRights", node1.getTextContent());
            return node1.getTextContent();
        } catch (Exception e) {
            return "-1";
        }

    }

    public ArrayList<LatLng> getDirection(Document doc) {
        NodeList nl1, nl2, nl3;
        ArrayList<LatLng> listGeopoints = new ArrayList<LatLng>();
        nl1 = doc.getElementsByTagName("step");
        if (nl1.getLength() > 0) {
            for (int i = 0; i < nl1.getLength(); i++) {
                Node node1 = nl1.item(i);
                nl2 = node1.getChildNodes();

                Node locationNode = nl2
                        .item(getNodeIndex(nl2, "start_location"));
                nl3 = locationNode.getChildNodes();
                Node latNode = nl3.item(getNodeIndex(nl3, "lat"));
                double lat = Double.parseDouble(latNode.getTextContent());
                Node lngNode = nl3.item(getNodeIndex(nl3, "lng"));
                double lng = Double.parseDouble(lngNode.getTextContent());
                listGeopoints.add(new LatLng(lat, lng));

                locationNode = nl2.item(getNodeIndex(nl2, "polyline"));
                nl3 = locationNode.getChildNodes();
                latNode = nl3.item(getNodeIndex(nl3, "points"));
                ArrayList<LatLng> arr = decodePoly(latNode.getTextContent());
                for (int j = 0; j < arr.size(); j++) {
                    listGeopoints.add(new LatLng(arr.get(j).latitude, arr
                            .get(j).longitude));
                }

                locationNode = nl2.item(getNodeIndex(nl2, "end_location"));
                nl3 = locationNode.getChildNodes();
                latNode = nl3.item(getNodeIndex(nl3, "lat"));
                lat = Double.parseDouble(latNode.getTextContent());
                lngNode = nl3.item(getNodeIndex(nl3, "lng"));
                lng = Double.parseDouble(lngNode.getTextContent());
                listGeopoints.add(new LatLng(lat, lng));
            }
        }

        return listGeopoints;
    }

    private int getNodeIndex(NodeList nl, String nodename) {
        for (int i = 0; i < nl.getLength(); i++) {
            if (nl.item(i).getNodeName().equals(nodename))
                return i;
        }
        return -1;
    }

    private ArrayList<LatLng> decodePoly(String encoded) {
        ArrayList<LatLng> poly = new ArrayList<LatLng>();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;
        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;
            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            LatLng position = new LatLng((double) lat / 1E5, (double) lng / 1E5);
            poly.add(position);
        }
        return poly;
    }
}

片段

public class FormComoChegarEmpresa2 extends Fragment implements GoogleMap.OnMyLocationChangeListener {
    private MapView mapView;
    private GoogleMap map;
    private final String TAG = getClass().getSimpleName() + "->";
    private static Empresa empresa;


    //source
    private Double sourceLat, sourceLong;
    //target
    private Double targetLat, targetLong;


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

        if(getArguments().getSerializable("empresa") != null){
            empresa = (Empresa)getArguments().getSerializable("empresa");
            targetLat = empresa.getEndereco().getLatitude();
            targetLong = empresa.getEndereco().getLongitude();
        }

        mapView = (MapView)view.findViewById(R.id.mapView);
        mapView.onCreate(savedInstanceState);

        map = mapView.getMap();
        if(map != null){
            listeners();
        }


        try {
            MapsInitializer.initialize(this.getActivity());
        } catch (Exception e) {
            Log.e(TAG, e.getLocalizedMessage());
        }

        return  view;
    }

    private void listeners(){
        map.setMyLocationEnabled(true);
        map.setOnMyLocationChangeListener(this);
    }

    @Override
    public void onMyLocationChange(Location location) {
        GMapV2Direction md = new GMapV2Direction();
        map.addMarker(new MarkerOptions().position(new LatLng(location.getLatitude(), location.getLongitude())).title("It's Me!"));
        sourceLat = map.getMyLocation().getLatitude();
        sourceLong = map.getMyLocation().getLongitude();
        LatLng sourcePosition = new LatLng(sourceLat, sourceLong);
        LatLng destPosition = new LatLng(targetLat, targetLong);
        Document doc = md.getDocument(sourcePosition, destPosition, GMapV2Direction.MODE_DRIVING);
        ArrayList<LatLng> directionPoint = md.getDirection(doc);
        PolylineOptions rectLine = new PolylineOptions().width(3).color(Color.RED);

        for (int i = 0; i < directionPoint.size(); i++) {
            rectLine.add(directionPoint.get(i));
        }
        Polyline polylin = map.addPolyline(rectLine);
        // Updates the location and zoom of the MapView
        CameraUpdate cameraUpdate = CameraUpdateFactory.newLatLngZoom(new LatLng(targetLat,
                targetLong), 10);
        map.animateCamera(cameraUpdate);
        map.setOnMyLocationChangeListener(null);
    }

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

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

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

Answer 1

将此添加到您的代码中，我的位置已更改！

Marker marker = map.addMarker(new MarkerOptions().position(new LatLng(location.getLatitude(), location.getLongitude())).title("It's Me!"));
    LatLng markerLocation = marker.getPosition();
    sourceLat = markerLocation.latitude();
    sourceLong = markerLocation.Longitude();

GoogleMap.OnMyLocationChangeListener 抛出 NullPointerException

GoogleMap.OnMyLocationChangeListener throws NullPointerException

android

google-maps-android-api-2