NoSuchMethodError the method was called on Null - flutter

Question

in this code below WeatherModel tried to get current location of android phone,
my problem here is once I start runing it show NoSuchMethod Found, and it says reciever is null,
as I tried a lot of debugging just to see where is my problem.
I now understand that my problem is when I create instance of Location() in WeatherModel, longitude and latitude are null, it never gets value and I dont know why...
Sorry for my bad english :(
const apiKey = 'e3653190f2b1d4803287b3074ecfe618';
const apiWeatherURL = 'https://api.openweathermap.org/data/2.5/weather';
class WeatherModel {
Future<dynamic> getLocationWeather() async {
Location location = Location();
NetworkHelper networkHelper = NetworkHelper(
'https://api.openweathermap.org/data/2.5/weather?lat=${location.latitude}&lon=${location.longitude}&appid=$apiKey');
var weatherData = networkHelper.getData();
return weatherData;
}
}
.....
class Location {
double latitude;
double longitude;
Future<void> getCurrentLocation() async {
try {
Position _position = await Geolocator()
.getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
longitude = _position.longitude;
print(longitude);
latitude = _position.latitude;
print(latitude);
} catch (e) {
print(e);
}
}
}
.........
class NetworkHelper {
NetworkHelper(this.url);
final url;
Future getData() async {
http.Response response = await http.get(url);
if (response.statusCode == 200) {
var data = jsonDecode(response.body);
print(" Sarkawtua $data");
return data;
} else
print("Error ${response.statusCode} keshay Internet");
}
}

Answer 1

Because you instance fields are not updated, so they are null. You have method for getting current location but it's not fired in getLocationWeather.
Future<dynamic> getLocationWeather() async {
Location location = Location();
await location.getCurrentLocation();
NetworkHelper networkHelper = NetworkHelper(
'https://api.openweathermap.org/data/2.5/weather?lat=${location.latitude}&lon=${location.longitude}&appid=$apiKey');
var weatherData = await networkHelper.getData();
return weatherData;
}
Edit: You also must await networkHelper.getData() method to get not Future Object.