我是 C# 新手，我的編碼有問題。我在運行時遇到錯誤。似乎沒有分配對象數組。歡迎任何幫助/提示。我有一個帶有修理室的“建筑”類。預計不會改變或增加房間。房間有很多屬性。在我的“Home”類中，我想通過對象數組訪問所有房間以及特定房間。提前致謝：Class Home{private void StartProgramm()        {            //get all Objects of class "Building"            Building[] building = Building.Buildings;            //System.NullReferenceException during runtime            set_label_header(building[0].Name);            //Access to room1            Building room1 = Building.room1;            set_label_header(room1.Name);            //Get room2            Building room2 = Building.GetBuilding("room2");            set_label_header(room2?.Name);         }}    class Building    {        public string Name { get; set; }        public ArrayList tool_groupList = new ArrayList();        public ArrayList pos_List = new ArrayList();        public ArrayList inv_list = new ArrayList();        public static Building room1;        public static Building room2;        public static Building[] Buildings;    public Building()            {            //create room 1 and add some attributes            room1 = new Building { Name = "room1" };            room1.tool_groupList.Add(1);            room1.tool_groupList.Add(2);            room1.pos_List.Add(14);            room1.pos_List.Add(15);            room1.pos_List.Add(16);            room1.pos_List.Add(17);            Iventory[] inventories = Inventory.get_inventories();            room1.areaList.AddRange(inventories);        }