getlastknownlocation zawsze zwraca wartość null po ponownym zainstalowaniu pliku APK za pośrednictwem eclipse

Question

Niedawno stworzyłem prostą aplikację, aby uzyskać lokalizację GPS i wyświetlić na telefonie z Androidem. Na początku mogę uzyskać lokalizację po kilku próbach, ale po ponownym zainstalowaniu pliku apk funkcja getLastKnownLocation() zawsze zwraca wartość pustą. Środowisko

Development używane: - API 10 Gingerbread 2.3.6 - dostawca GPS służy

poniżej jest kod zastosowałem w moim android projektu:

 public class MyActivity extends MapActivity{ 
protected void onCreate(Bundle savedInstanceState) { 


    mapView = (MapView)findViewById(R.id.myTripMap); 
    mapController = mapView.getController(); 
    mapView.setSatellite(false); 
    mapView.setStreetView(true); 
    mapView.displayZoomControls(false); 
    mapView.setBuiltInZoomControls(true);// 
    mapView.setClickable(true); 
    mapController.setZoom(14);  


    Criteria criteria = new Criteria(); 
    criteria.setAccuracy(Criteria.ACCURACY_FINE); 
    criteria.setAltitudeRequired(false); 
    criteria.setBearingRequired(false); 
    criteria.setCostAllowed(true); 
    criteria.setPowerRequirement(Criteria.POWER_LOW); 
    provider = locationManager.getBestProvider(criteria, true); 
    location = locationManager.getLastKnownLocation(provider); 

    updateMyCurrentLoc(location); 

    locationManager.requestLocationUpdates(provider, 2, 1,locationListener); 



} 


      private final LocationListener locationListener = new LocationListener() { 
     public void onLocationChanged(Location location) { 
      updateMyCurrentLoc(location); 
     } 

     public void onProviderDisabled(String provider){ 
      updateMyCurrentLoc(null); 
     } 

     public void onProviderEnabled(String provider){ } 
     public void onStatusChanged(String provider, int status, 
            Bundle extras){ } 
     }; 


     private void updateMyCurrentLoc(Location location) { 



      if (location != null) { 

      // other codes to get the address and display 
      Toast.makeText(getBaseContext(), "provider used : "+provider).show(); //testing purpose 
      } 
      else { 
       str = "No location found"; 
       Toast.makeText(getBaseContext(), str, Toast.LENGTH_SHORT).show(); 
      } 

     } 
    } 

Może ktoś sugerują możliwe rozwiązanie rozwiązać wartość pustą zwróconą przez getLastKnownLocation()? Każda pomoc zostanie doceniona. Dzięki.

Answer 1

getLastKnownLocation() ta zwraca ostatnią znaną lokalizację ... po ponownym zainstalowaniu aplikacji nie będą miały żadnego ostatnią znaną lokalizację ... więc będzie skutkować NPE ... zamiast skorzystać z poniższego kodu

public Location getLocation() { 
    try { 
     locationManager = (LocationManager) mContext 
       .getSystemService(LOCATION_SERVICE); 

     // getting GPS status 
     isGPSEnabled = locationManager 
       .isProviderEnabled(LocationManager.GPS_PROVIDER); 

     // getting network status 
     isNetworkEnabled = locationManager 
       .isProviderEnabled(LocationManager.NETWORK_PROVIDER); 

     if (!isGPSEnabled && !isNetworkEnabled) { 
      // no network provider is enabled 
     } else { 
      this.canGetLocation = true; 
      if (isNetworkEnabled) { 
       locationManager.requestLocationUpdates(
         LocationManager.NETWORK_PROVIDER, 
         MIN_TIME_BW_UPDATES, 
         MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
       Log.d("Network", "Network Enabled"); 
       if (locationManager != null) { 
        location = locationManager 
          .getLastKnownLocation(LocationManager.NETWORK_PROVIDER); 
        if (location != null) { 
         latitude = location.getLatitude(); 
         longitude = location.getLongitude(); 
        } 
       } 
      } 
      // if GPS Enabled get lat/long using GPS Services 
      if (isGPSEnabled) { 
       if (location == null) { 
        locationManager.requestLocationUpdates(
          LocationManager.GPS_PROVIDER, 
          MIN_TIME_BW_UPDATES, 
          MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
        Log.d("GPS", "GPS Enabled"); 
        if (locationManager != null) { 
         location = locationManager 
           .getLastKnownLocation(LocationManager.GPS_PROVIDER); 
         if (location != null) { 
          latitude = location.getLatitude(); 
          longitude = location.getLongitude(); 
         } 
        } 
       } 
      } 
     } 

    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

    return location; 
} 

on pracował dla mnie ... powinien pracować dla Ciebie ...

Answer 2

po prostu trzeba dodać jeszcze jedną linię w kodzie

if (locationManager != null) { 
    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this); 
    location = locationManager 
      .getLastKnownLocation(LocationManager.GPS_PROVIDER); 

    if (location != null) { 
     latitude = location.getLatitude(); 
     longitude = location.getLongitude(); 

    } else { 
     Toast.makeText(
       mContext, 
       "Location Null", Toast.LENGTH_SHORT).show(); 
    } 
} 

Answer 3

Spróbuj następujący kod

LocationManager locationManager = (LocationManager) getActivity() 
      .getSystemService(Context.LOCATION_SERVICE); 

    String locationProvider = LocationManager.NETWORK_PROVIDER; 
    Location lastlocation = locationManager.getLastKnownLocation(locationProvider); 

    String CurLat = String.valueOf(lastlocation.getLatitude()); 
    String Curlongi= String.valueOf(lastlocation.getLongitude()); 

Answer 4

Mam ten sam problem po ponownym zainstalowaniu za pomocą eclipse. Rozwiązałem problem z ustawieniami Androida/bezpieczeństwa/aplikacji i potwierdziłem uprawnienia lokalizacji do aplikacji.

Answer 5

To rozwiązanie jest moim małym usprawnieniem dla kodu @Karan Mer.

public Location getLocation() { 
    int MIN_TIME_BW_UPDATES = 10000; 
    int MIN_DISTANCE_CHANGE_FOR_UPDATES = 10000; 
    try { 
     locationManager = (LocationManager) getApplicationContext() 
       .getSystemService(LOCATION_SERVICE); 

     boolean isGPSEnabled = locationManager 
       .isProviderEnabled(LocationManager.GPS_PROVIDER); 

     boolean isPassiveEnabled = locationManager 
       .isProviderEnabled(LocationManager.PASSIVE_PROVIDER); 

     boolean isNetworkEnabled = locationManager 
       .isProviderEnabled(LocationManager.NETWORK_PROVIDER); 

     if (isGPSEnabled || isNetworkEnabled || isPassiveEnabled) { 

      this.canGetLocation = true; 
      // if GPS Enabled get lat/long using GPS Services 
      if (isGPSEnabled && location == null) { 
        locationManager.requestLocationUpdates(
          LocationManager.GPS_PROVIDER, 
          MIN_TIME_BW_UPDATES, 
          MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
        Log.d("GPS", "GPS Enabled"); 
        if (locationManager != null) { 
         location = locationManager 
           .getLastKnownLocation(LocationManager.GPS_PROVIDER); 
        } 
      } 
      if (isPassiveEnabled && location == null) { 
       locationManager.requestLocationUpdates(
         LocationManager.PASSIVE_PROVIDER, 
         MIN_TIME_BW_UPDATES, 
         MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
       Log.d("Network", "Network Enabled"); 
       if (locationManager != null) { 
        location = locationManager 
          .getLastKnownLocation(LocationManager.PASSIVE_PROVIDER); 
       } 
      } 

      if (isNetworkEnabled && location == null) { 
       locationManager.requestLocationUpdates(
         LocationManager.NETWORK_PROVIDER, 
         MIN_TIME_BW_UPDATES, 
         MIN_DISTANCE_CHANGE_FOR_UPDATES, this); 
       Log.d("Network", "Network Enabled"); 
       if (locationManager != null) { 
        location = locationManager 
          .getLastKnownLocation(LocationManager.NETWORK_PROVIDER); 
       } 
      } 

     }else{ 
      return null; 
     } 

    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

Ciesz