我有以下接口：

public interface IObject{
double x {get;}
double y {get;}
List<IObject> List{get; set;}
}

和这个类

public class Holder<T> where T : IObject {
private T myItem;
public void ChangeItemList(T item){
myItem.List = item.List;
}

但是编译器不喜欢ChangeItemList方法，并在此行：

However the compiler doesn't like the ChangeItemList method and on this line :

myItem.List = item.List;

给我这个错误：

gives me this error:

Cannot convert source type 'List<T>' to target type 'List<IObject>'

为什么我不能做到这一点，什么是对于这种情况好的解决办法？ 谢谢

Why can't I do it and what is a good solution for this scenario? thank you

推荐答案

我不知道你想达到什么，但下面的编译和运行没有异常：

I am not sure what you want to achieve but the following compiles and runs without exceptions:

class Program
{
    static void Main(string[] args)
    {
        var holder = new Holder<IObject>();
        holder.MyItem = new Object { List = new List<IObject>() };
        holder.ChangeItemList(new Object { List = new List<IObject>() });
    }
}

public class Object : IObject
{
    public List<IObject> List { get; set; }
}

public interface IObject
{
    List<IObject> List { get; set; }
}

public class Holder<T> where T : IObject
{
    public T MyItem { get; set; }

    public void ChangeItemList(T item)
    {
        MyItem.List = item.List;
    }
}