How do I create an array of objects in constructor?

I have two classes:

game

element

I want to be able to define an array of element objects in a game object. When I try this I get the warning message "..is never assigned to, and will always have its default value null"; in the local variables in the debugger I can see that the array exists, but all entries are null. The class Element works as I would expect. If I assign element objects to an array in Main it works, but not when I move the code to the Game constructor.

What am I doing wrong? I'm new to C# so it could be something very b开发者_JAVA百科asic. Code below. Many thanks.

class Element
    {
      public Element()
      {
        elements = new List<int>(3);
        elements.Add(1);
        elements.Add(2);
        elements.Add(3);

      }

        List<int> elements;

        public void PrintElement()
      {
          for (int i = 0; i < 3; i++)
          {
              Console.WriteLine("Element {0}: {0}", i + 1, elements[i]);
          }
      }

    }


class Game
    {

            public Game()
            {
                Element1 = new Element();
                Element2 = new Element();
                Element3 = new Element();
                Element[] ThisGame = new Element[3];
                ThisGame[0]= Element1;
                ThisGame[1] = Element2;
                ThisGame[2] = Element3;

            }

            public Element[] ThisGame;
            private Element Element1;
            private Element Element2;
            private Element Element3;

        public void PrintGameElement(int number)
        {
            ThisGame[number].PrintElement();
        }

    }


    class Program
    {
            Game MyGame;
        static void Main(string[] args)
        {

            Game MyGame = new Game();
            MyGame.PrintGameElement(2);


            Console.Read();
        }
    }

In Game, you are re-declaring ThisGame.

Change

Element[] ThisGame = new Element[3];

to

ThisGame = new Element[3];

Your Game constructor should look like this:

    public Game()
    {
        Element1 = new Element();
        Element2 = new Element();
        Element3 = new Element();
        ThisGame = new Element[3];
        ThisGame[0]= Element1;
        ThisGame[1] = Element2;
        ThisGame[2] = Element3;

    }

You need to set the list object to something when you initialize it.

List<int> elements = null; 

OR

List<int> elements = new List<int>(); 

look at this code it may help you to make some order in your code:

Element class :

class Element
    {
        //property on element to save element data
        public string ElementData { get; set; }
        public Element(string data)
        {
            ElementData = data;
        }
    }

Game class :

class Game
    {
        //property on Game to save all elements
        Element[] Elements { get; set; }
        public Game(Element[] elements)
        {
            Elements = elements;
        }

        public void PrintGameElements()
        {
            foreach (var element in Elements)
            {
                Console.WriteLine(element.ElementData);
            }
        }

        public void PrintElement(int index)
        {
            Console.WriteLine(Elements[index].ElementData);
        }
    }

Main function that initialize the array and pass it to the game :

static void Main(string[] args)
        {
            //initialize the array 
            var elements = new[]
            {
                new Element("data x"),
                new Element("data y"),
                new Element("data z")
            };

            //pass the elements to the game
            var game = new Game(elements);

            //print the second element
            game.PrintElement(1);

            //print all elements
            game.PrintGameElements();

            Console.ReadKey();
        }
    }