Question

I’m working on learning C# and I’ve ran into a problem with an example in my book.
I cant figure out why it sets my Room objets Exit to the appropriate Loactions, but my RoomWithDoor.Exits to null.

    public Form1()
            {
                InitializeComponent();
                CreateObjects();
                MoveToANewLocation(livingRoom);
            }
            public void CreateObjects()
            {
                livingRoom = new RoomWithDoor("living room", "an antique carpet", "an oak door with a brass knob");
                livingRoom.Exits = new Locations[] { diningRoom, kitchen };
                livingRoom.DoorLocation = frontYard;

                diningRoom = new Room("dining room", "crystal chandelier");
                diningRoom.Exits = new Locations[] { livingRoom, kitchen };

    abstract class Locations
    {
        public Locations(string name)
        {
            this.name = name;
        }
        public Locations[] Exits;
        private string name;
        public string Name { get { return name; } }

class Room : Locations
{
    public Room(string name, string decoration)
        : base(name)
    {
        this.decoration = decoration;
    }
class RoomWithDoor : Room, IHasExteriorDoor
{
    public RoomWithDoor(string name, string decoration, string doorDescription)
        : base(name, decoration)
    {
        this.doorDescription = doorDescription;
    } 

So, this works

private void MoveToANewLocation(Locations newLocation)
        {
    currentLocation = newLocation;
            currentLocationExit = currentLocation.Exits[0];
            MessageBox.Show(diningRoom.Name);

but this dose not

    MessageBox.Show(livingRoom.Exits[0].Name);

Answer 1

livingRoom = new RoomWithDoor("living room", "an antique carpet", "an oak door with a brass knob");
livingRoom.Exits = new Locations[] { diningRoom, kitchen };
livingRoom.DoorLocation = frontYard;

diningRoom = new Room("dining room", "crystal chandelier");
diningRoom.Exits = new Locations[] { livingRoom, kitchen };

This doesn’t work as you expect. Since you assign a new value to diningRoom after you assign livingRoom.Exits, livingRoom.Exits will still have the value diningRoom had at the time of assignment, which is likely null.