Question

您好我试着在片段中找到位置。但我无法获得位置。

LocationManager locationmanager= (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);返回null.how我能解决吗

SocialFragment.java

public class SocialFragment extends Fragment {
MapView mMapView;
private GoogleMap googleMap;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.activity_maps, container, false);

    mMapView = (MapView) rootView.findViewById(R.id.map);
    mMapView.onCreate(savedInstanceState);

    mMapView.onResume(); // needed to get the map to display immediately

    try {
        MapsInitializer.initialize(getActivity().getApplicationContext());
    } catch (Exception e) {
        e.printStackTrace();
    }

    mMapView.getMapAsync(new OnMapReadyCallback() {
        @Override
        public void onMapReady(GoogleMap mMap) {
            googleMap = mMap;
            // For dropping a marker at a point on the Map
            LatLng sydney = new LatLng(-34, 151);
            googleMap.addMarker(new MarkerOptions().position(sydney).title("Marker Title").snippet("Marker Description"));
            // For zooming automatically to the location of the marker
            CameraPosition cameraPosition = new CameraPosition.Builder().target(sydney).zoom(12).build();
            googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));

            LocationManager locationmanager= (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);
            Criteria criteria = new Criteria();
            String provider = locationmanager.getBestProvider(criteria, false);
            if (ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getContext(), android.Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                // TODO: Consider calling
                //    ActivityCompat#requestPermissions
                // here to request the missing permissions, and then overriding
                //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                //                                          int[] grantResults)
                // to handle the case where the user grants the permission. See the documentation
                // for ActivityCompat#requestPermissions for more details.
                return;
            }
            mMap.setMyLocationEnabled(true);

        }
    });

    return rootView;
}



@Override
public void onResume() {
    super.onResume();
    mMapView.onResume();
}

@Override
public void onPause() {
    super.onPause();
    mMapView.onPause();
}

@Override
public void onDestroy() {
    super.onDestroy();
    mMapView.onDestroy();
}

@Override
public void onLowMemory() {
    super.onLowMemory();
    mMapView.onLowMemory();
}

}

MainActivity.java

public class MainActivity extends AppCompatActivity
    implements NavigationView.OnNavigationItemSelectedListener {
FragmentManager mFragmentManager;
FragmentTransaction mFragmentTransaction;
ArrayList country, city, districts;
StringBuffer stringBuffer = new StringBuffer();
String response;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    mFragmentManager = getSupportFragmentManager();
    mFragmentTransaction = mFragmentManager.beginTransaction();
    mFragmentTransaction.replace(R.id.containerView, new TabFragment()).commit();

    try {
        City();
    } catch (IOException e) {
        e.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    }
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_camera) {

        // Handle the camera action
    } else if (id == R.id.nav_gallery) {

    } else if (id == R.id.nav_slideshow) {

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}}

Answer 1

请添加logcat错误或结果以获取更多详细信息。同时在你的onMapready中试试这个：

// enable location buttons
       googleMap.setMyLocationEnabled(true);
       googleMap.getUiSettings().setMyLocationButtonEnabled(true);

       // fetch last location if any from provider - GPS.
       final LocationManager locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
       final Location loc = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

       if (loc == null) {

          final LocationListener locationListener = new LocationListener() {
                    @Override
                    public void onLocationChanged(final Location location) {

                        // getting location of user
                        final double latitude = location.getLatitude();
                        final double longitude = location.getLongitude();
                         // do something with Latlng
                    }

                    @Override
                    public void onStatusChanged(String provider, int status, Bundle extras) {
                    }

                    @Override
                    public void onProviderEnabled(String provider) {
                        // do something
                    }

                    @Override
                    public void onProviderDisabled(String provider) {
                        // notify user "GPS or Network provider" not available
                    }
                };

                locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 10000, 500, locationListener);
                locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 10000, 500, locationListener);
                } 
                else {
                // do something with last know location
                }

Answer 2

尝试添加

在LocationManager locationmanager= (LocationManager) getActivity().getSystemService(Context.LOCATION_SERVICE);

之外的

onMapReady

如何在Fragment中获取位置？

2 个答案: