Question 75996 in Flutter Question posted in
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Flutter error: NoSuchMethodError (NoSuchMethodError: The method 'getDouble' was called on null

Upon starting my Flutter app it shows me the following error:

NoSuchMethodError (NoSuchMethodError: The method 'getDouble' was called on null.
Receiver: null
Tried calling: getDouble("lat"))

This is the section of the code that should be causing the error:

    _userCurrentLocationUpdate(Position updatedPosition) async {
    double distance = await Geolocator.distanceBetween(
        prefs.getDouble('lat'),
        prefs.getDouble('lng'),
        updatedPosition.latitude,
        updatedPosition.longitude);
    Map<String, dynamic> values = {
      "id": prefs.getString("id"),
      "position": updatedPosition.toJson()
    };
    if (distance >= 50) {
      if (show == Show.RIDER) {
        sendRequest(coordinates: requestModelFirebase.getCoordinates());
      }
      _userServices.updateUserData(values);
      await prefs.setDouble('lat', updatedPosition.latitude);
      await prefs.setDouble('lng', updatedPosition.longitude);
    }
  }
Tags:

3

Answers


  1. 0

    getDouble returns nullable double. You can provide default value on null case.

    Geolocator.distanceBetween(
    prefs.getDouble('lat')?? .0,
    prefs.getDouble('lng')?? .0,

    You won’t have data until you save(first run).

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  2. 0

    Your error and current code suggests that you forgot to initialize prefs variable before calling the method on it. So you need to initialize it.

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  3. 0

    It is because you are passing a nullable value prefs.getDouble('lat'), but the parameter can’t be null, so you are getting this error.

    Change

    double distance = await Geolocator.distanceBetween(
        prefs.getDouble('lat'),
        prefs.getDouble('lng'),
        updatedPosition.latitude,
        updatedPosition.longitude);

    to

    double distance = await Geolocator.distanceBetween(
        prefs.getDouble('lat') ?? .0, //👈 Now the parameter is .0 if the getDouble is null 
        prefs.getDouble('lng') ?? .0, // You can change the default value as well.
        updatedPosition.latitude,
        updatedPosition.longitude);
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