投递列表<b>到列表<a>

Question

I want to to cast a list of object type A to a list of object type B, where A inherit B.

Concretely :

public class A : B
{
    public string name { get; set; }
}

public class B
{
    public B() { }
}

I parse a JSON string that I cast to my list of type A :

B elem = ((JArray)_configuration).ToObject<List<A>>();

And I have this error :

Cannot implicitly convert type 'System.Collections.Generic.List< A>' to 'System.Collections.Generic.List< B>'

I tried to cast it :

List<B> elem = (List<B>)((JArray)_configuration).ToObject<List<A>>();

but got this error :

Cannot convert type 'System.Collections.Generic.List< A>' to 'System.Collections.Generic.List< B>'

I couldn't find help, maybe because I don't know what to look for, so apologies if it has been answered somewhere already !

Answer 1

您可以使用catch(CUserException *e)。

Enumerable.Cast<>()

但是List<B> list = myList.Cast<B>().ToList(); 会创建一个副本。如果你只想迭代这些项目。请勿使用ToList()并将其作为ToList()处理。它会在飞行中变得懒惰。

Answer 2

好的，只要找到答案就可以提供帮助。如果没有，请告诉我，我将删除该问题。对不起！

只需要这样做：

List<B> elem = new List<B>(((JArray)_configuration).ToObject<List<A>>());

Answer 3

也许你应该阅读this，使用list.selectall。

您也可以尝试this for arrays。