Raw通用类型C＃列表

Question

I just started digging through C# being a java user. I run into a problem, declaring a list of generic raw type. Consider class A<T> and B : A<String> , C : A<Int16> . Now I want to declare something like List<A> list . I face a problem at this kind of declaration, getting a " generic type argument requires 1 argument ". Is there any way I could do something like that? Or there are some other patterns in C# to use?

Answer 1

When using a generic type you have to specify the type parameter. In this case to declare a List of A you have to specify T . For example:

List<A<int>> list = new List<A<int>>();

or seeing as B and C both derive from A and explicitly specify T , then you can have:

List<B> list = new List<B>();
List<C> list = new List<C>();

UPDATE #1

Before using the following example I must admit I've not given it much thought on just how useful/practical using a List of dynamic would be or what issues may present themselves, but just thought I would offer the suggestion.

public class A<T>
{
    public T Value { get; set; }
}  

List<A<dynamic>> list = new List<A<dynamic>>();

list.Add(new A<dynamic> { Value = "Hello World" });
list.Add(new A<dynamic> { Value = 100 });

foreach(A<dynamic> item in list)
{
    Console.WriteLine(item.Value);
}