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:-
