Zoo (Contratto di interfaccia di classe)

Class Animale ' un animale
    Public Overridable Function FaiRumore() As String
        Return "Boh"
    End Function
End Class
Class Leone ' un animale che ruggisce
    Inherits Animale
    Public Overrides Function FaiRumore() As String
        Return "ruggisco"
    End Function
End Class

Class Elefante ' un animale che barrisce
    Inherits Animale
    Public Overrides Function FaiRumore() As String
        Return "barrisco"
    End Function
End Class

Class ElefanteIndiano
    Inherits Elefante

    Public Overrides Function FaiRumore() As String
        Return "barrisco, ma in indiano..."
    End Function
End Class
Class Cane
    Inherits Animale

    Public Overrides Function FaiRumore() As String
        Return "abbaio"
    End Function
End Class
Module Module1
    ' Modellare un sistema che visualizzi i versi fatti dagli animali inseriti in uno zoo
    Sub ProcessaZoo(zoo() As Animale)
        For Each animale As Animale In zoo
            Console.WriteLine(animale.FaiRumore())
        Next
    End Sub

    Sub Main()
        Dim leo As New Leone
        Dim ele As New Elefante
        Dim eli As New ElefanteIndiano
        Dim can As New Cane
        Dim animali() As Animale = {can, leo, ele, eli} ' array di animali
        ProcessaZoo(animali)
    End Sub

End Module