Question

即时创建一个小型移动应用，应该可以让我在谷歌地图上找到我当前的位置。我让它早些时候工作，我能够点击其中一个按钮，它放大到我当前的位置。现在由于某种原因我得到以下错误

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

它指向我的代码的第53行，发布在下面：

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));
    }

}

第53行指的是：double myLongitude = myLocation.getLongitude();

不知道为什么会这样任何帮助将不胜感激！

Answer 1

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

在您的代码中，您获得的是NullPointerException，因为在第53行中，myLocation为空。

Location.getLongitude（）null对象引用

1 个答案: