Location.getLongitude（）null object reference

-2

即時創建一個小的移動應用程序，應該讓我能夠在谷歌地圖上找到我目前的位置。我讓它工作得更早，我可以點擊其中一個按鈕，它放大到我當前的位置。現在，由於某種原因，即時得到以下錯誤Location.getLongitude（）null object reference

java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLongitude()' on a null object reference

它朝我的代碼53行指出這是下面貼：

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback { 

    private GoogleMap mMap; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_maps); 
     // Obtain the SupportMapFragment and get notified when the map is ready to be used. 
     SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager() 
       .findFragmentById(R.id.map); 
     mapFragment.getMapAsync(this); 
    } 

    @Override 
    public void onMapReady(GoogleMap googleMap) { 
     mMap = googleMap; 

     mMap.getUiSettings().setZoomControlsEnabled(true); 
     mMap.setMyLocationEnabled(true); 

     // Get LocationManager object from System Service LOCATION_SERVICE 
     LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 

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

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

     // Get Current Location 
     Location myLocation = locationManager.getLastKnownLocation(provider); 

     double myLongitude = myLocation.getLongitude(); 
     double myLatitude = myLocation.getLatitude(); 

     // Create a LatLng object for the current location 
     LatLng latLng = new LatLng(myLongitude, myLatitude); 

     Marker me = mMap.addMarker(new MarkerOptions() 
      .position(new LatLng(myLatitude, myLongitude)) 
       .title("Im here!") 
       .icon(BitmapDescriptorFactory.fromResource(R.drawable.people)) 
     ); 
     // Zoom into my current location 
     mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(myLatitude, myLongitude), 15.0f)); 
    } 

}

53號線是指：double myLongitude = myLocation.getLongitude();

不知道爲什麼這發生了任何幫助將不勝感激！

來源

2016-03-24 Spud91

locationManager.getLastKnownLocation(provider)可以返回null，如文檔here中所述。

在你的代碼中，你得到一個NullPointerException，因爲在第53行中，myLocation爲空。

來源

2016-03-24 17:31:58 jrnorth

Location.getLongitude（）null object reference

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