无法在android.app.ActivityThread.performLaunchActivity启动活动组件信息：java.lang.NullPointerException

我在android应用程序中使用Google map v2。当我试图查看此活动时，会出现此错误

01-22 08:46:26.271: E/AndroidRuntime(1349): FATAL EXCEPTION: main
01-22 08:46:26.271: E/AndroidRuntime(1349): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mad.restaurantfinderrm/com.mad.restaurantfinderrm.MapActivity}: java.lang.NullPointerException
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.os.Looper.loop(Looper.java:137)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.ActivityThread.main(ActivityThread.java:5103)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at java.lang.reflect.Method.invokeNative(Native Method)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at java.lang.reflect.Method.invoke(Method.java:525)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at dalvik.system.NativeStart.main(Native Method)
01-22 08:46:26.271: E/AndroidRuntime(1349): Caused by: java.lang.NullPointerException
01-22 08:46:26.271: E/AndroidRuntime(1349):     at com.mad.restaurantfinderrm.MapActivity.onCreate(MapActivity.java:74)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.Activity.performCreate(Activity.java:5133)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-22 08:46:26.271: E/AndroidRuntime(1349):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
01-22 08:46:26.271: E/AndroidRuntime(1349):     ... 11 more

这是我的MapActivity.java文件

 public class MapActivity extends FragmentActivity implements LocationListener {

    GoogleMap map;
    ArrayList<LatLng> markerPoints;
    ArrayList<LatLng> positions;

    String address;
    String restName;

    LatLng contactLocation = null;
    LatLng myLocationLL = null;
    Address a;
    Location myLocation = null;
    Marker myMarker;
    Marker contactMarker;

    private LocationManager locationManager;
    private String provider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_map);

        positions = new ArrayList<LatLng>();

        // Getting reference to SupportMapFragment of the activity_main
        SupportMapFragment fm = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);

        // Getting Map for the SupportMapFragment
        map = fm.getMap();

        // Enable MyLocation Button in the Map
        map.setMyLocationEnabled(true);

        // get my current location
        locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
        boolean enabledGPS = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);
        //boolean enabledWiFi = locationManager
            //  .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!enabledGPS) {
            Toast.makeText(this, "GPS signal not found", Toast.LENGTH_LONG)
                    .show();
            // TODO
            // Intent intent = new
            // Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            // startActivity(intent);

        }

        Criteria criteria = new Criteria();
        provider = locationManager.getBestProvider(criteria, false);
        myLocation = locationManager.getLastKnownLocation(provider);

        // Initialize the location fields
        if (myLocation != null) {
            Toast.makeText(this, "Selected Provider " + provider,
                    Toast.LENGTH_SHORT).show();
            onLocationChanged(myLocation);
            myLocationLL = new LatLng(myLocation.getLatitude(),
                    myLocation.getLongitude());
            positions.add(myLocationLL);
        } else {

            positions.add(null);
        }

        // get contacts address location
        Intent intent = getIntent();
        address = intent.getExtras().getString("address");
        Log.v("ADDRESS", address);
        restName = intent.getExtras().getString("restName");
        Log.v("ADDRESS", restName);
        String fulladdress = restName + ", " + address;
        Geocoder geocoder = new Geocoder(getApplicationContext(),
                Locale.getDefault());
        List<Address> fromLocationName = null;
        try {
            fromLocationName = geocoder.getFromLocationName(fulladdress, 1);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        if (fromLocationName != null && fromLocationName.size() > 0) {
            a = fromLocationName.get(0);
            contactLocation = new LatLng(a.getLatitude(), a.getLongitude());
            contactMarker = map.addMarker(new MarkerOptions().position(
                    contactLocation).title(restName));
            contactMarker.showInfoWindow();

            positions.add(contactLocation);

            // move the camera instantly to the festival with a zoom of X.
            map.moveCamera(CameraUpdateFactory.newLatLng(contactLocation));

            map.animateCamera(CameraUpdateFactory.zoomTo(16), 2000, null);
        } else {
            positions.add(null);
        }

        // Initializing
        markerPoints = new ArrayList<LatLng>();

        if (positions.size() == 2) {
            for (LatLng position : positions) {

                // Adding new item to the ArrayList
                markerPoints.add(position);

                // Creating MarkerOptions
                MarkerOptions options = new MarkerOptions();

                // Setting the position of the marker
                options.position(position);

                /**
                 * For the start location, the color of marker is GREEN and     for
                 * the end location, the color of marker is RED.
                 */
                if (markerPoints.size() == 1) {
                    options.icon(BitmapDescriptorFactory
                                .defaultMarker(BitmapDescriptorFactory.HUE_GREEN));
                } else if (markerPoints.size() == 2) {
                    options.icon(BitmapDescriptorFactory
                            .defaultMarker(BitmapDescriptorFactory.HUE_RED));
                }

                // Add new marker to the Google Map Android API V2
                map.addMarker(options);

                // Checks, whether start and end locations are captured
                if (markerPoints.size() >= 2) {
                    LatLng origin = markerPoints.get(0);
                    LatLng dest = markerPoints.get(1);

                    // Getting URL to the Google Directions API
                    String url = getDirectionsUrl(origin, dest);

                    DownloadTask downloadTask = new DownloadTask();

                    // Start downloading json data from Google Directions API
                    downloadTask.execute(url);
                }
            }
        }
    }

    private String getDirectionsUrl(LatLng origin, LatLng dest) {

        // Origin of route
        String str_origin = "origin=" + origin.latitude + ","
                + origin.longitude;

        // Destination of route
        String str_dest = "destination=" + dest.latitude + "," + dest.longitude;

        // Sensor enabled
        String sensor = "sensor=false";

        // Building the parameters to the web service
        String parameters = str_origin + "&" + str_dest + "&" + sensor;

        // Output format
        String output = "json";

        // Building the url to the web service
        String url = "https://maps.googleapis.com/maps/api/directions/"
                + output + "?" + parameters;

        return url;
    }

    /** A method to download json data from url */
    private String downloadUrl(String strUrl) throws IOException {
        String data = "";
        InputStream iStream = null;
        HttpURLConnection urlConnection = null;
        try {
            URL url = new URL(strUrl);

            // Creating an http connection to communicate with url
            urlConnection = (HttpURLConnection) url.openConnection();

            // Connecting to url
            urlConnection.connect();

            // Reading data from url
            iStream = urlConnection.getInputStream();

            BufferedReader br = new BufferedReader(new InputStreamReader(
                    iStream));

            StringBuffer sb = new StringBuffer();

            String line = "";
            while ((line = br.readLine()) != null) {
                sb.append(line);
            }

            data = sb.toString();

            br.close();

        } catch (Exception e) {
            Log.d("Exception while downloading url", e.toString());
        } finally {
            iStream.close();
            urlConnection.disconnect();
        }
        return data;
    }

    // Fetches data from url passed
    private class DownloadTask extends AsyncTask<String, Void, String> {

        // Downloading data in non-ui thread
        @Override
        protected String doInBackground(String... url) {

            // For storing data from web service
            String data = "";

            try {
                // Fetching the data from web service
                data = downloadUrl(url[0]);
            } catch (Exception e) {
                Log.d("Background Task", e.toString());
            }
            return data;
        }

        // Executes in UI thread, after the execution of
        // doInBackground()
        @Override
        protected void onPostExecute(String result) {
            super.onPostExecute(result);

            ParserTask parserTask = new ParserTask();

            // Invokes the thread for parsing the JSON data
            parserTask.execute(result);
        }
    }

    /** A class to parse the Google Places in JSON format */
    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]);
                DirectionsJSONParser parser = new DirectionsJSONParser();

                // 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;
            //MarkerOptions markerOptions = new MarkerOptions();

            // 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);
            }

            // Drawing polyline in the Google Map for the i-th route
            map.addPolyline(lineOptions);
        }
    }

    @Override
    public void onLocationChanged(Location location) {
        LatLng coordinate = new LatLng(location.getLatitude(),
                location.getLongitude());

        // Toast.makeText(this, "Location " +
        // coordinate.latitude+","+coordinate.longitude,
        // Toast.LENGTH_LONG).show();

        if (myMarker != null) {
            // Toast.makeText(this, "!=null", Toast.LENGTH_LONG).show();
            myMarker.remove();
        }
        myMarker = map.addMarker(new MarkerOptions().position(coordinate)
                .title("Here I am!"));

        myMarker.showInfoWindow();

        // move the camera instantly to the festival with a zoom of X.
        map.moveCamera(CameraUpdateFactory.newLatLng(coordinate));

        map.animateCamera(CameraUpdateFactory.zoomTo(16), 2000, null);
    }

    @Override
    public void onProviderDisabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onProviderEnabled(String arg0) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
        // TODO Auto-generated method stub

    }

    }

---

请帮帮我。更正代码对我来说是最好的。

试着使用此代码并对gps进行一次注释，gps在室内不起作用

boolean enabledWiFi=locationManager .isProviderEnabledLocationManager.NETWORK\u提供程序

---

SupportMapFragment的getMap方法返回NULL。

该文件中的第74行是什么？如果getMap返回NULL，请参阅我的答案。