Visual Basic .NET Language Classes Abstract Classes
Example
If classes share common functionality you can group this in a base or abstract class. Abstract classes can contain partial or no implementation at all and allow the derived type to override the base implementation.
Abstract classes within VisualBasic.NET must be declared as MustInherit and cannot be instantiated.
Public MustInherit Class Vehicle
Private Property _numberOfWheels As Integer
Private Property _engineSize As Integer
Public Sub New(engineSize As Integer, wheels As Integer)
_numberOfWheels = wheels
_engineSize = engineSize
End Sub
Public Function DisplayWheelCount() As Integer
Return _numberOfWheels
End Function
End Class
A sub type can then inherit this abstract class as shown below:
Public Class Car
Inherits Vehicle
End Class
Car will inherit all of the declared types within vehicle, but can only access them based upon the underlying access modifier.
Dim car As New Car()
car.DisplayWheelCount()
In the above example a new Car instance is created. The DisplayWheelCount() method is then invoked which will call the base class Vehicles implementation.
