如何让两个类引用相同的对象列表？

Question

我有3个类(Rawmaterial、RawmaterialRepository和Storage)，我想知道如何才能使Storage类具有为RawmaterialRepository创建的相同列表作为属性？在类程序中，我实例化了木头和存储库对象，并使用addRawmaterial方法将木头添加到存储库。最后，我实例化了storage1并调用了StockAlert方法，但它对我不起作用。出现一条错误消息，指出Warehouse类中的列表为空。这是我的代码。

public class Rawmaterial
{
    public string name;
    public int stock;

    public Rawmaterial(string name, int stock)
    {
        this.name = name;
        this.stock = stock;
    }
}
public class RawmaterialRepository
{
    public List<Rawmaterial> listRM = new List<Rawmaterial>();
    public RawmaterialRepository()
    {
        listRM = new List<Rawmaterial>();
    }
    public void addRawmaterial(Rawmaterial rawmaterial)
    {
        listRM.Add(rawmaterial);
    }
}
public class Storage
{
    public string name;
    public RawmaterialRepository listRM;
    public Storage(string name)
    {
        this.name = name;
        listRM = ; //this is a problem
    }

    public void StockAlert()
    {
        foreach (Rawmaterial rawmaterial in listRM.listRM) //this is a problem
        {
            if (rawmaterial.stock  <= 10)
            {
                Console.WriteLine("Sotck Alert");
            } 
        }
    }
}
class Program
{
    static void Main(string[] args)
    {
        Rawmaterial wood = new Rawmaterial("wood", 300) ;
        RawmaterialRepository repository = new RawmaterialRepository();
        repository.addRawmaterial(wood);
        Storage storage1 = new Storage("storage1");
        storage1.StockAlert();
}

另外，你能帮我一下吗？我是个新手。

Answer 1

您可以在存储构造函数中将存储库传递给存储：

public Storage(string name, RawmaterialRepository listRM)
    {
        this.name = name;
        this.listRM = listRM; //this is a problem
    }

然后在Main中

Storage storage1 = new Storage("storage1", repository );

Answer 2

您希望使用名为“通过引用传递”的资源...尽管可以使用ref关键字明确表示，但C#的默认行为是按引用传递自定义类的对象

当您通过引用传递时，将传递对象引用(即存储对象的内存位置)，以便在函数或其他类中不创建新对象，而只使用来自外部世界的对象。

仅供参考，在python中，默认行为也是按引用传递的。

public class Storage
{
        public string name;
        public RawmaterialRepository listRM;
        public Storage(string name, ref RawmaterialRepository repository )
        {
            this.name = name;
            listRM = repository; //this will be a reference to the same memory you created outside
        }
        public void StockAlert()
        {
        foreach (Rawmaterial rawmaterial in listRM.listRM)     //this is a problem
        {
                if (rawmaterial.stock  <= 10)
                {
                    Console.WriteLine("Sotck Alert");
                } 
            }
        }
}
class Program
{
    static void Main(string[] args)
    {
        Rawmaterial wood = new Rawmaterial("wood", 300) ;
        RawmaterialRepository repository = new         RawmaterialRepository();
        repository.addRawmaterial(wood);
        Storage storage1 = new Storage("storage1", repository); // just pass the object normally
        storage1.StockAlert();
}