Question

我一直在应用程序中工作，我需要获取用户的当前位置。同样，我在清单文件中添加了 COARSE_LOCATION 和 FINE_LOCATION 权限。

我还在应用程序中添加了运行时权限，并检查了应用信息中是否启用了权限。

我一直在使用以下代码来获取用户的位置。

 LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        String provider = locationManager.getBestProvider(new Criteria(), true);

        if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            return;
        } else {
            Location locations = locationManager.getLastKnownLocation(provider);
            List<String> providerList = locationManager.getAllProviders();
            if (null != locations && null != providerList && providerList.size() > 0) {
                double longitude = locations.getLongitude();
                double latitude = locations.getLatitude();
                Geocoder geocoder = new Geocoder(getApplicationContext(), Locale.getDefault());
                try {
                    List<Address> listAddresses = geocoder.getFromLocation(latitude, longitude, 1);
                    if (null != listAddresses && listAddresses.size() > 0) {
                        cityname = listAddresses.get(0).getLocality();
                        countryname = listAddresses.get(0).getCountryName();
                        regionname = listAddresses.get(0).getSubLocality();

                        System.out.println("Location updates = " + cityname + regionname + countryname);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

这段代码在某些设备上运行良好（REDMI NOTE 3，REDMI NOTE 4，MOTO E），在某些设备中它返回null（SAMSUNG J7，MOTO G）。

我在哪里出错了？任何建议对我的项目和学习都非常满意。

Answer 1

我遇到了同样的问题。我将locationManager.getLastKnownLocation(provider);代码放在循环中，直到我获得当前位置的纬度和经度。见下面的代码：

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

                 Location location = null;
                 do {
                     location = getLastKnownLocation();
                  }
                  while (location == null);

                   currentLatitude = location.getLatitude();
                  currentLongitude = location.getLongitude();
  } 




private Location getLastKnownLocation() {
        List<String> providers = locationManager.getProviders(true);

        Location bestLocation = null;
        for (String provider : providers) {
            Location l = null;
            try {
                l = locationManager.getLastKnownLocation(provider);
            } catch (SecurityException e) {
                e.printStackTrace();
            }
            if (l == null) {
                continue;
            }
            if (bestLocation == null
                    || l.getAccuracy() < bestLocation.getAccuracy()) {
                bestLocation = l;
            }
        }
        if (bestLocation == null) {
            return null;
        }
        return bestLocation;
    }

Answer 2


Location location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);

if (location == null) {

            do{
                location = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
            }while (location == null);

            String message = String.format(
                    "New Location \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude()
            );
            Toast.makeText(getActivity(), message, Toast.LENGTH_LONG).show();
            Log.d("locationLinster",message);
}else{
      String message = String.format(
                    "New Location \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude()
            );
      Toast.makeText(getActivity(), message, Toast.LENGTH_LONG).show();
            Log.d("locationLinster",message);
}

这确实有助于启动提供程序...如果我们第一次遇到此问题，则需要时间。但是一旦启动，它就像梦一样。

感谢@RG

某些设备上的位置返回null

2 个答案: