Interface in VB.NET
In this article we will discuss about the Interface functionality.
Interface:- An interface is a type that defines a programming contract without any implementation at all, means that an interface defines the calling signature for a set of methods and properties ,and that it never contains any form of implementation.There are three important aspect to working
with Interface
- Someone must define Interface.
- One or more programmers must create classes that implement this interface.
- Some client side code must be written against the interface type
Defining an Interface:-To create an Interface definition, you use the Interface construct.
inside the interface construct, you can declare the signature for methods and properties.
Public Interface Test
'creating an Interface named Test
Sub display()
Function Div() As Double
'specifying two methods in an interface
End Interface
Note:- All members of an Interface type are implicitly public and abstract. to this end ,it is illegal to use the Public keyword or Must Override keyword on a member inside and interface definition
Implementing an Interface:- yours first step towards implementing an Interface is to use the Implement keyword
with a class defination
Public Class One Implements Test
'implementing interface in class One
Public i As Double = 12
Public j As Double = 12.17
Sub display() Implements Test.display
'implementing the method specified in interface
Console.WriteLine("sum of i+j is" & i + j)
End Sub
Public Function Div() As Double Implements Test.Multiply
'implementing the method specified in interface
Console.WriteLine("Div is" & i / j)
End Function
End Class
Note:- You can Implement multiple interfaces by adding comma-delimited list of interface name after the implement keywords. such as Public Class One :Employee,Student,College, etc.
Coding for Interface:-
Module Module1
Sub Main()
Dim OneObj As New One()
Dim TwoObj As New Two()
'creating objects of class One and Two
OneObj.display()
OneObj.Div()
TwoObj.display()
TwoObj.Div()
'accessing the methods from classes as specified in the interface
End Sub
End Module
Public Interface Test
'creating an Interface named Test
Sub display()
Function Div() As Double
'specifying two methods in an interface
End Interface
Public Class One
Implements Test
'implementing interface in class One
Public i As Double = 35
Public j As Double = 12.17
Sub display() Implements Test.display
'implementing the method specified in interface
Console.WriteLine("sum of i+j is" & i + j)
End Sub
Public Function Div() As Double Implements Test.Div
'implementing the method specified in interface
Console.WriteLine("Div is " & i / j)
End Function
End Class
Public Class Two
Implements Test
'implementing the interface in class Two
Public a As Double = 56
Public b As Double = 32.17
Sub display() Implements Test.display
Console.WriteLine("Welcome to Interfaces")
End Sub
Public Function Div() As Double Implements Test.Div
Console.WriteLine("Div is " & a / b)
End Function
End Class
Output:-