C#•2y ago

❔ Non-nullable property must contain a non-null value when exiting constructor

I know what it says and what it wants my to do. However, my situation is: I have a bunch of objects (as properties) and that not all of them needs instantiating in a main class constructor. Given a condition, some will be and some won't be. In case of one that won't be, I still have no idea how to make the warning go away. Any suggestion? I'm sure how to Google this since using the warning would send me to a non-desirable direction.

7 Replies

Thinker•2y ago

If some properties might not be set, then make them nullable

EddieVOP•2y ago

@🌈 Thinker 🌈 I did, however the Console still warns me about null

Thinker•2y ago

Can you show your code?

Tinefol•2y ago

Mind providing code snippet?

EddieVOP•2y ago

public class World
{
    public int[,] WorldState { get; set; }
    public Fountain Fountain { get; set; }
    public Pit[] Pits { get; set; }
    public Maelstrom?[] Maelstroms { get; set; } 
    public Entrance Entrance { get; set; } = new Entrance(); 
    
    public World(string? size)
    {

        switch (size)
        {
            case "small":
                WorldState = new int[4, 4]; 
                Fountain = new Fountain(new Point(3, 1));
                Pits = new Pit[1] { new Pit(new Point(1, 1)) };
                break;

            case "medium":
                WorldState = new int[6, 6]; 
                Fountain = new Fountain(new Point(4, 3));
                Pits = new Pit[2] 
                    {
                        new Pit(new Point(3, 1)), 
                        new Pit(new Point(2, 3))
                    };
                Maelstroms = new Maelstrom[1] { new Maelstrom(new Point(4, 2))};
                break;

            case "large":
                WorldState = new int[8, 8]; 
                Fountain = new Fountain(new Point(4, 3));
                Pits = new Pit[2] 
                    {
                        new Pit(new Point(3, 1)), 
                        new Pit(new Point(2, 3))
                    };
                Maelstroms = new Maelstrom[1] { new Maelstrom(new Point(4, 2))};
                break;

            default:
                throw new NotSupportedException("Invalid world size.");
            
        }
        
    }

public class World
{
    public int[,] WorldState { get; set; }
    public Fountain Fountain { get; set; }
    public Pit[] Pits { get; set; }
    public Maelstrom?[] Maelstroms { get; set; } 
    public Entrance Entrance { get; set; } = new Entrance(); 
    
    public World(string? size)
    {

        switch (size)
        {
            case "small":
                WorldState = new int[4, 4]; 
                Fountain = new Fountain(new Point(3, 1));
                Pits = new Pit[1] { new Pit(new Point(1, 1)) };
                break;

            case "medium":
                WorldState = new int[6, 6]; 
                Fountain = new Fountain(new Point(4, 3));
                Pits = new Pit[2] 
                    {
                        new Pit(new Point(3, 1)), 
                        new Pit(new Point(2, 3))
                    };
                Maelstroms = new Maelstrom[1] { new Maelstrom(new Point(4, 2))};
                break;

            case "large":
                WorldState = new int[8, 8]; 
                Fountain = new Fountain(new Point(4, 3));
                Pits = new Pit[2] 
                    {
                        new Pit(new Point(3, 1)), 
                        new Pit(new Point(2, 3))
                    };
                Maelstroms = new Maelstrom[1] { new Maelstrom(new Point(4, 2))};
                break;

            default:
                throw new NotSupportedException("Invalid world size.");
            
        }
        
    }

Here's the code. I'm doing an exercise, if player chooses "small", there won't be maelstroms in the game So the console tells me, Maelstrom must not be null when existing in the constructor.

Tinefol•2y ago

You need ? after the [], not before the way its written by you is an non-nullable array of nullables you need nullable array though

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Non-nullable property must contain a non-null value when exiting constructor