替换ICollection中的元素

这里没有黑魔法：ICollection没有顺序，仅提供Add/ Remove方法。您唯一的解决方案是检查实际的实现是否还包括其他内容，例如IList：

public static void Swap(this ICollection collection, T oldValue, T newValue)
{
    // In case the collection is ordered, we'll be able to preserve the order
    var collectionAsList = collection as IList;
    if (collectionAsList != null)
    {
        var oldIndex = collectionAsList.IndexOf(oldValue);
        collectionAsList.RemoveAt(oldIndex);
        collectionAsList.Insert(oldIndex, newValue);
    }
    else
    {
        // No luck, so just remove then add
        collection.Remove(oldValue);
        collection.Add(newValue);
    }

}