Classes, Interfaces, Structs, and Enumerations

You design a VB .NET class using a class in PowerDesigner. Structures are classes with the <<structure>> stereotype, and enumerations are classes with the <<enumeration>> stereotype.

• VB .NET classes can contain events, variables, constants, methods, constructors and properties. The following specific kinds of classes are also supported:

  • MustInherit class is equivalent to an abstract class. To design this type of class you need to create a class and select the Abstract check box in the General tab of the class property sheet.

    Public MustInherit Class Customer Private Name As Char Private ID As Integer End Class

  • NotInheritable class is equivalent to a final class. To design this type of class, you need to create a class and select the Final check box in the General tab of the class property sheet.

    Public NotInheritable Class FinalClass Private At1 As Object Private At2 As Object End Class

  Note: You design a VB .NET nested type using an inner class or interface.

• VB .NET interfaces are modeled as standard interfaces. They can contain events, properties, and methods; they do not support variables, constants, and constructors.

• Structures can implement interfaces but do not support inheritance; they can contain events, variables, constants, methods, constructors, and properties. The following structure contains two attributes and a constructor operation:

  ... Public Class Point Protected Y As Integer Protected X As Integer Public Sub New() End Sub End Class ...

• Enumeration class attributes are used as enumeration values. The following items must be set:

  • Data Type - using the EnumDataType extended attribute of the enumeration (for example Byte, Short, or Long)

  • Initial Expression - using the Initial Value field of an enum attribute

  For example:

  Public Enum Day Monday Tuesday Wednesday Thursday Friday Saturday Sunday FirstDay = Monday LastDay = Sunday End Enum