VB.Net: Determine if an Object or Class Implements and Interface

The Problem

You want to know if a class called MyClass implements interface IMyInterface, or the object myObject inplements interface IMyInterface.

Unfortunately, you can’t do:

If MyClass Is IMyInterface Then

The Solution

It isn’t exactly intuitive, but for a class you can do this:

If GetType(IMyInterface).IsAssignableFrom(MyClass) Then
    ' Do something interesting, e.g.
    CType(MyObject, IMyInterface).MethodOnIMyInterface()
End If

Or for an object:

 If GetType(IMyInterface).IsAssignableFrom(MyObject.GetType) Then
    ' Do something interesting, e.g.
    CType(MyObject, IMyInterface).MethodOnIMyInterface()
End If