Java通用类类型的C＃等效语法

Question

I am looking for a equivalent syntax for java code below in C#.

ArrayList<Class <? extends A>> list = new ArrayList<Class<? extends A>>();
// Sample usage
list.add(A.class);
list.add(B.class); // B extends A

The list above basically only accept Sub Class of A (or A) as input.

Thank in advance.

Answer 1

There's no equivalent for that in C#. The generics in C# are quite different to those in Java in various ways, including the way covariance and contravariance work.

You could have a generic method (or generic type) with a constraint on the type parameter like this:

public void Foo<T>(IList<T> list) where T : SomeClass

or

public class Foo<T> where T : SomeClass

... but Type itself (the .NET equivalent of Class<T> ) is non-generic, so there's no way of saying "This is a list of types which extend A ".

If you give us more information about what you're trying to achieve, we may be able to help you more.

Answer 2

The C# language has generics from version 2.0 onwards:

http://msdn.microsoft.com/en-us/library/512aeb7t.aspx

Type constraints can be found here:

http://msdn.microsoft.com/en-us/library/d5x73970.aspx

I'm mostly a Java programmer not a C# one so I'm not sure the exact syntax of what you need but you should be able to find it from there.