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.logik.

•Created by .logik. on 3/6/2023 in #help

✅ 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);
        }

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();
            }
        }

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");
        }

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

13 replies

CC#

•Created by .logik. on 11/26/2022 in #help

Application called an interface that was marshalled for a different thread?

31 replies

Gaming

Programming