尝试获取手机位置时如何修复不可为空的实例

Question

I'm trying to get the location of my phone with geolocation however the variable that stores location when you a press the button to get location has to be store as null at the beginning as I do not have the location of the phone yet however when I do that I get an error 'Non-nullable instance field 'currentposition' must be initialized' how to I fix this

this is my code

class _HomeState extends State<Home> {
  String currentAddress = 'My Address';
  

  Position currentposition;
  void initState() {}

  Future<Position> _determinePosition() async {
    bool serviceEnabled; //check location service is enabled
    LocationPermission permission;

    serviceEnabled = await Geolocator.isLocationServiceEnabled();
    if (!serviceEnabled) {
      Fluttertoast.showToast(msg: 'Please enable Your Location Service');
    }

    permission = await Geolocator.checkPermission();
    if (permission == LocationPermission.denied) {
      permission = await Geolocator.requestPermission();
      if (permission == LocationPermission.denied) {
        Fluttertoast.showToast(msg: 'Location permissions are denied');
      }
    }

    if (permission == LocationPermission.deniedForever) {
      Fluttertoast.showToast(
          msg:
              'Location permissions are permanently denied, we cannot request permissions.');
    }

    Position position = await Geolocator.getCurrentPosition(
        desiredAccuracy: LocationAccuracy.high);

    try {
      List<Placemark> placemarks =
          await placemarkFromCoordinates(position.latitude, position.longitude);

      Placemark place = placemarks[0];

      setState(() {
        currentposition = position;
        currentAddress =
            "${place.locality}, ${place.postalCode}, ${place.country}";
        print(currentposition);
      });
    } catch (e) {
      print(e);
    }
    throw "";
  }

Answer 1

If you declare a variable then you also have to initialize it by passing some value to it. But in any case you want to assign value later then you can define it as late making this change to your variable you can also make it nullable by using ?

late Position currentposition; //late initialize but not null

and nullable with late

late Position? currentposition; //late initialize nullable