Question

地图问题

我有这个代码来获取当前位置并将地图移动到该位置但是这段代码有时会显示我之前所处的位置，而不是目前的位置，并且由于某种原因它现在已经开始强制关闭

private void initilizeMap() {
    if (googleMap == null) {

        FragmentManager fragmentManager = getSupportFragmentManager();
        SupportMapFragment mapFragment =  (SupportMapFragment)
            fragmentManager.findFragmentById(R.id.iqamah_map);
        googleMap = mapFragment.getMap();           

        googleMap.getUiSettings().setCompassEnabled(true);
        googleMap.getUiSettings().setZoomControlsEnabled(true);
        googleMap.getUiSettings().setMyLocationButtonEnabled(true);
        googleMap.getUiSettings().setZoomControlsEnabled(false);
        googleMap.setMyLocationEnabled(true); // false to disable



        // Getting LocationManager object from System Service LOCATION_SERVICE
        LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);


        // Creating a criteria object to retrieve provider
        Criteria criteria = new Criteria();


        // Getting the name of the best provider
        String provider = locationManager.getBestProvider(criteria, true);


        // Getting Current Location
        Location location = locationManager.getLastKnownLocation(provider);

        googleMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);

//            CameraPosition cameraPosition = new CameraPosition.Builder().target(
//                    new LatLng(17.385044, 78.486671)).zoom(12).build();

//            googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

        // Getting latitude of the current location
        double latitude = location.getLatitude();

        // Getting longitude of the current location
        double longitude = location.getLongitude();

        url = "https://codingsquared-prod.apigee.net/masaajid?lat="+Double.toString(latitude)+"&long="+Double.toString(longitude);

        // Creating a LatLng object for the current location
        LatLng latLng = new LatLng(latitude, longitude);

        TextView txtview = (TextView) findViewById(R.id.iqamah_listview_text);
        txtview.setText("latitude="+Double.toString(latitude)+" longitude="+Double.toString(longitude));

        // Showing the current location in Google Map
        googleMap.moveCamera(CameraUpdateFactory.newLatLng(latLng));

        // Zoom in the Google Map
        googleMap.animateCamera(CameraUpdateFactory.zoomTo(15));


    }

}

logcat：

06-28 01:05:01.554: E/AndroidRuntime(13477): FATAL EXCEPTION: main
06-28 01:05:01.554: E/AndroidRuntime(13477): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sahaab.android.muslimzone.test/com.sahaab.muslimzone.activity.IqamahActivity}: java.lang.NullPointerException
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2266)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2316)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.ActivityThread.access$600(ActivityThread.java:150)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1298)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.os.Looper.loop(Looper.java:213)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.ActivityThread.main(ActivityThread.java:5225)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at java.lang.reflect.Method.invokeNative(Native Method)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at java.lang.reflect.Method.invoke(Method.java:525)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:741)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:132)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at dalvik.system.NativeStart.main(Native Method)
06-28 01:05:01.554: E/AndroidRuntime(13477): Caused by: java.lang.NullPointerException
06-28 01:05:01.554: E/AndroidRuntime(13477):    at com.sahaab.muslimzone.activity.IqamahActivity.initilizeMap(IqamahActivity.java:155)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at com.sahaab.muslimzone.activity.IqamahActivity.onCreate(IqamahActivity.java:103)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.Activity.performCreate(Activity.java:5133)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
06-28 01:05:01.554: E/AndroidRuntime(13477):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2230)
06-28 01:05:01.554: E/AndroidRuntime(13477):    ... 12 more

还尝试了当前位置：

        Location myLocation = googleMap.getMyLocation();
        LatLng myLatLng = new LatLng(myLocation.getLatitude(),
                myLocation.getLongitude());

        CameraPosition myPosition = new CameraPosition.Builder()
                .target(myLatLng).zoom(17).bearing(90).tilt(30).build();
        googleMap.animateCamera(
            CameraUpdateFactory.newCameraPosition(myPosition));

Answer 1

试试这个，它是我用来获取用户当前位置的： - （它检查GPS或NetworkProvider是否可用）

public LatLng getCurrentLocation(Context context)
{
    try
    {
        LocationManager locMgr = (LocationManager) context.getSystemService(Context.LOCATION_SERVICE);
        Criteria criteria = new Criteria();
        String locProvider = locMgr.getBestProvider(criteria, false);
        Location location = locMgr.getLastKnownLocation(locProvider);

        // getting GPS status
        boolean isGPSEnabled = locMgr.isProviderEnabled(LocationManager.GPS_PROVIDER);
        // getting network status
        boolean isNWEnabled = locMgr.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNWEnabled)
        {
            // no network provider is enabled
            return null;
        }
        else
        {
            // First get location from Network Provider
            if (isNWEnabled)
                if (locMgr != null)
                    location = locMgr.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled)
                if (location == null)
                    if (locMgr != null)
                        location = locMgr.getLastKnownLocation(LocationManager.GPS_PROVIDER);
        }

        return new LatLng(location.getLatitude(), location.getLongitude());
    }
    catch (NullPointerException ne)
    {
        Log.e("Current Location", "Current Lat Lng is Null");
        return new LatLng(0, 0);
    }
    catch (Exception e)
    {
        e.printStackTrace();
        return new LatLng(0, 0);
    }
}

Answer 2

从代码中删除以下代码

  // Getting LocationManager object from System Service LOCATION_SERVICE
    LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);


    // Creating a criteria object to retrieve provider
    Criteria criteria = new Criteria();


    // Getting the name of the best provider
    String provider = locationManager.getBestProvider(criteria, true);


    // Getting Current Location
    Location location = locationManager.getLastKnownLocation(provider);

添加此代码

LocationManager locationManager;
boolean hasNetwrokProvider;

    if (locationManager == null) {
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    }

    hasNetwrokProvider = locationManager
            .isProviderEnabled(LocationManager.NETWORK_PROVIDER);
    if (!hasNetwrokProvider) {
                   // Alert for no gps available.
               //ConstantsMethod.buildAlertMessageNoGps(HomeActivity.this);
        return;

    }
    locationManager.requestLocationUpdates(
            LocationManager.NETWORK_PROVIDER, 0, 100,
            locationListenerNetwork);
    location = locationManager
            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);

实施LocationLienter并在活动

中添加以下代码

public LocationListener locationListenerNetwork = new LocationListener() {
    public void onLocationChanged(Location location) {
        // locationResult.gotLocation(location);
        locationManager.removeUpdates(this);
        locationManager.removeUpdates(locationListenerGps);

    }

    public void onProviderDisabled(String provider) {
    }

    public void onProviderEnabled(String provider) {
    }

    public void onStatusChanged(String provider, int status, Bundle extra) {
    }

};

谷歌地图当前位置NullPointerException

2 个答案: