XNA游戏项目拖放-如何实现对象交换？

Question

I'm making an inventory system and I'm stuck at the part where the items should be moved from cell to cell by simple drag'n'dropping.

There is an Item[,] Inventory array which holds the items, object fromCell, toCell which should hold the references to cells to operate with when mouse button is released, but when I try doing this:

object temp = toCell;
toCell = fromCell;
fromCell = temp;

...the game is only swapping object references and not the actual objects. How do I make this work?

UPD: Thanks to Bartosz I figured this out. Turns out you can safely use a reference to array of objects and change it with saved indices of objects you wish to swap.

Code can be like this:

object fromArray, toArray;
int fromX, fromY, toX, toY;

// this is where game things happen

void SwapMethod()
{
    object temp = ((object[,])toArray)[toX, toY];
    ((object[,])toArray)[toX, toY] = ((object[,])fromArray)[fromX, fromY];
    ((object[,])fromArray)[fromX, fromY] = temp;
}

Answer 1

How about this?

internal static void Swap<T>(ref T one, ref T two)
{
    T temp = two;
    two = one;
    one = temp;
}

And all your swapping becomes this.

Swap(Inventory[fromCell], Inventory[toCell]);

Also, you can add the extension for the arrays (if more confortable).

public static void Swap(this Array a, int indexOne, int indexTwo)
{
    if (a == null)
        throw new NullReferenceException(...);

    if (indexOne < 0 | indexOne >= a.Length)
        throw new ArgumentOutOfRangeException(...);

    if (indexTwo < 0 | indexTwo >= a.Length)
        throw new ArgumentOutOfRangeException(...);

    Swap(a[indexOne], a[indexTwo]);
}

To use it like so:

Inventory.Swap(fromCell, toCell);

Answer 2

Why not using indexes to your Inventory array: int fromCell, toCell .

var temp = Inventory[toCell];
Inventory[toCell] = fromCell;
Inventory[fromCell] = temp;

You're modeling inventory as 2D array of slots, so it seems fairly safe to use indexes to access it.