C#C
C#•3y ago
.logik.

✅ Help with non-nullable field must contain a non-null value when exiting constructor.

Following an online tutorial and trying to resolve nullable reference warnings (the tutorial was before nullable reference types were introduced).

I have a GameSession class with the constructor defined as 
public GameSession()
        {
            CurrentPlayer = new Player
            {
                Name = "MyName",
                Gold = 1000000,
                CharacterClass = "Ranger",
                HitPoints = 10,
                ExperiencePoints = 0,
                Level = 1,
            };

            CurrentWorld = WorldFactory.CreateWorld();

            CurrentLocation = CurrentWorld.LocationAt(0, -1);
        }


The error is regarding the backing field private Location _currentLocation which is set using the property 
public Location CurrentLocation
        {
            get => _currentLocation;
            set
            {
                _currentLocation = value;
                OnPropertyChanged();
            }
        }

Furthermore the LocationAt method is non-nullable defined as 
public Location LocationAt(int xCoordinate, int yCoordinate)
        {
            foreach (Location loc in _locations)
            {
                if (loc.XCoordinate == xCoordinate && loc.YCoordinate == yCoordinate)
                {
                    return loc;
                }
            }

            throw new LocationNotFoundException($"Location at x:{xCoordinate} y:{yCoordinate} does not exist");
        }


So my question is, why am I still getting the warning and what is the best approach to fixing it?

As I understand it, the compiler already knows that LocationAt will return a Location and the backing field _currentLocation should be set by the CurrentLocation property in the constructor. Why does it still think currentLocation is null when exiting constructor?

TIA
Was this page helpful?