Interfaces in VB.NET
This article shows how to implement interfaces in VB.NET.
Interfaces
An interface is a skeleton of rules that must be enforced in the inherited types. An interface contains only the signatures of methods, properties, events, indexers, and delegates.
Important Rules of Interfaces
- An interface can inherit from one or more base interfaces.
- An interface or class inherited from more than one base interfaces is called multiple inheritance.
- A derived class must implement all interface members.
The following code snippet creates two interfaces IList and ICounter. The IListCounter interface is inherited from both IList and ICounter interfaces.
Interface IList
Property Count() As Integer
End Interface
Interface ICounter
Sub Count(ByVal i As Integer)
End Interface
Interface IListCounter
Inherits IList
Inherits ICounter
End Interface
The TestInterface module shows how to use IList and ICounter interface members through IListCounter.
Module TestInterface
Sub F(ByVal x As IListCounter)
CType(x, IList).Count = 1 ' Ok, invokes IList.Count.
CType(x, ICounter).Count(1) ' Ok, invokes ICounter.Count.
End Sub
End Module