Abstraction (C# and VB.Net Cross Reference Guide)

C# supports abstract class members and abstract classes using the abstract modifier.

An abstract class is a class with one or more abstract members and you cannot instantiate an abstract class. However, you can have additional implemented methods and properties.

An abstract member is either a method (implicitly virtual), property, indexer, or event in an abstract class. You can add abstract members ONLY to abstract classes using the abstract keyword. Then you override it in a descendant class with Override.

abstract public class Cyborg : System.Object

{

  abstract public void Speak(string pMessage);

}

public class Series600 : Cyborg

{

  public override void Speak(string pMessage)  

  {

    MessageBox.Show(pMessage);  

  }

}

 C# Abstraction (abstract, override)  

VB.Net supports abstract class members and abstract classes using the MustInherit and MustOverride modifiers.

An abstract class is indicated with a MustInherit modifier and is a class with one or more abstract members and you cannot instantiate an abstract class. However, you can have additional implemented methods and properties.

An abstract member is either a method (implicitly virtual), property, indexer, or event in an abstract class. You can add abstract members ONLY to abstract classes using the MustOverride keyword. Then you override it in a descendant class with Overrides.

Public MustInherit Class Cyborg

  Public MustOverride Sub Speak(ByVal pMessage As String)

End Class

Public Class Series600

  Inherits Cyborg

  Public Overrides Sub Speak(ByVal pMessage As String)

    MessageBox.Show(pMessage)

  End Sub

End Class

 VB.Net Abstraction (MustInherit, MustOverride, Overrides)