VB .NET TypeOf Example

TypeOf Example.vb

Module Module1

    Class ClsTrack

    End Class

    Class ClsVehicularTrack : Inherits ClsTrack

    End Class

    Class ClsSpecialTrack : Inherits ClsTrack

    End Class

    Sub Main()
        Dim myTrack1 As ClsTrack = New ClsVehicularTrack()
        Dim myTrack2 As ClsTrack = New ClsSpecialTrack()

        Dim myVehicularTrack1 As ClsVehicularTrack
        Dim myVehicularTrack2 As ClsVehicularTrack
        Dim typeOfmyTrack1 As Type = myTrack1.GetType()
        Dim typeOfmyTrack2 As Type = myTrack2.GetType()
        Console.WriteLine("myTrack1 is a {0}", typeOfmyTrack1.Name) ' --> "myTrack1 is a ClsVehicularTrack"
        Console.WriteLine("myTrack2 is a {0}", typeOfmyTrack2.Name) ' --> "myTrack2 is a ClsSpecialTrack"
        If myTrack1.GetType().Name = "ClsVehicularTrack" Then
            myVehicularTrack1 = myTrack1
            Console.WriteLine("myVehicularTrack1 is a {0}", myVehicularTrack1.GetType().Name) ' --> "myTrack1 is a ClsVehicularTrack"
            'Else do something else...
        End If
        If myTrack2.GetType().Name = "ClsVehicularTrack" Then ' <-- This condition prevents the InvalidCastException
            myVehicularTrack2 = myTrack2 ' --> InvalidCastException (cannot assign a ClsSpecialTrack to a ClsVehicularTrack)
            Console.WriteLine("myVehicularTrack2 is a {0}", myVehicularTrack2.GetType().Name) ' --> not reached
            'Else do something else...
        End If
        If TypeOf myTrack1 Is ClsVehicularTrack Then
            myVehicularTrack1 = myTrack1
            Console.WriteLine("TypeOf myVehicularTrack1 is a {0}", myVehicularTrack1.GetType().Name)
            'Else do something else...
        End If
        If TypeOf myTrack2 Is ClsVehicularTrack Then ' <-- This condition prevents the InvalidCastException
            myVehicularTrack2 = myTrack2 ' --> InvalidCastException (cannot assign a ClsSpecialTrack to a ClsVehicularTrack)
            Console.WriteLine("myVehicularTrack2 is a {0}", myVehicularTrack2.GetType().Name) ' --> not reached
            'Else do something else...
        End If
        Console.WriteLine("Press any key to exit...")
        Console.ReadKey()
    End Sub

End Module