无法访问班级公共财产

Question

我创建了一个名为Building的类，其中包含一堆不同类型的房间，尽管目前我只有一个。 我现在尝试访问房间类型类中的属性，但由于某种原因，它无法让我访问它。

这是我的课：

public abstract class Building {

    public RoomType roomType { get; private set; }
    public RoomManager roomManager {get; private set;}
    public int x {get; private set;}
    public int y {get; private set;}

    public Building(int x, int y, RoomManager rm, RoomType rT){
        SetPosition(x,y);
        roomManager = rm;
        roomType    = rT;
    }
    void SetPosition(int tx, int ty){
        x = tx;
        y = ty;
    }
}

public class KitchenRoom : Building {
        public Kitchen reference {get; private set;}

        public KitchenRoom(int x, int y, RoomManager rM, Kitchen kitchen) : base(x,y,rM,RoomType.Kitchen){
            reference   = elevator;
        }
}

所以我创建了一个新的KitchenRoom，如下所示：

//Buildings = List<Building>();
//I use type Building because there will be more than just KitchenRoom in this list eventually.

buildings.Add(new KitchenRoom(x,y,go.getComponent<RoomManager>(),go.GetComponent<Kitchen>()));

所以现在我想访问值reference所以我这样做：

for(int i=0;i<buildings.Count; i++){
    if(buildings[i] is KitchenRoom){
       buildings[i].reference.someMethod(); // access to reference non existant
    }
} 

所以我似乎没有reference 。 但是我不知道我怎么了。

次要次要问题：

有人告诉我，也就是使用is KitchenRoom运行时类型检查不是一个好主意吗？ 但是我不知道该怎么做，这有什么道理吗，对此有更好的实现吗？

Answer 1

问题是您试图访问子类中的属性而不先进行转换。

该属性reference仅存在于您的类KitchenRoom ，而在Building中不存在

要访问reference财产KitchemRoom ，你应该投的元素KitchenRoom

代码示例

for(int i=0;i<buildings.Count; i++){
    if(buildings[i] is KitchenRoom){
       ((KitchenRoom)buildings[i]).reference.someMethod(); // Cast to KitchenRoom first, then access
    }
} 

与问题没有直接关系，但还有更多内容可以继续进行评论。

is关键字用于检查Object是否属于特定类型。 它不执行任何类型的转换，而是用于检查是否可以执行转换而不会引发错误。

代码示例

public class Garden : NotBuilding {
    //A class that does not inherit from Building
}


var aBuilding = new Building(); //An object of type building
var aKitchenRoom = new KitchenRoom(); //An object of type KitchenRoom, which inherits from Building in your code


Debug.Log(aBuilding is Building); //true
Debug.Log(aKitchenRoom is Building); //true
Debug.Log(aKitchenRoom is Garden); //false
Debug.Log(aKitchenRoom is NotBuilding); //false

as关键字是强制转换的另一种方式，其附加优点是如果强制转换失败，则不会抛出InvalidCastException 。

代码示例

在上面编写代码的另一种方法

for(int i=0;i<buildings.Count; i++){
    var kitchenRoom = buildings[i] as KitchenRoom; //Cast to a KitchenRoom. Method returns null if it fails
    if(kitchenRoom != null)
        kitchenRoom.reference.someMethod();
}