Interfaces in Visual Basic .NET

In this article, I will explain you about Interfaces and their implementation in Visual Basic .NET.
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In this article, I will explain you about Interfaces and their implementation in Visual Basic .NET.

Interfaces

Interfaces define what is referred to as a contract. Literally, an interface is a type that contain methods, properties and events that classes can implement. Interfaces also provide another way of implementing polymorphism. We leave it to the class to implement those methods which are specify in an interface. With the help of an interfaces we can achieve multiple inheritance which is not supported by Visual Basic .NET. Visual Basic .NET introduces the Interface statement, which allows you to define true interfaces as distinct entities from classes, and to implement them with an improved version of the Implements keyword.

The following code show you the implementation of Interfaces:

Imports System.Console
Module Module1
 
    Sub Main()
        Dim FirstObj As New First()
        Dim SecondObj As New Second()
        'creating objects of class First and Second
        FirstObj.Add()
        FirstObj.Multiply()
        SecondObj.Add()
        SecondObj.Multiply()
        'accessing the methods from classes as specified in the interface
        Read()
    End Sub
 
End Module
 
Public Interface Calculation
    'creating an Interface named Calculation
    Sub Add()
    Function Multiply() As Double
    'specifying two methods in an interface
End Interface
 
Public Class First
    Implements Calculation
    'implementing interface in class First
 
    Public A As Double = 24
    Public B As Double = 24.34
 
    Sub Add() Implements Calculation.Add
        'implementing the method specified in interface
        WriteLine("Sum of A+B is" & A + B)
        Read()
    End Sub
 
    Public Function Multiply() As Double Implements Calculation.Multiply
        'implementing the method specified in interface
        WriteLine("Multiple of A*B is" & A * B)
        Read()
    End Function
 
End Class
 
Public Class Second
    Implements Calculation
    'implementing the interface in class Second
 
    Public C As Double = 40
    Public D As Double = 64.34
 
    Sub Add() Implements Calculation.Add
        WriteLine("Sum of C+D is" & C + D)
        Read()
    End Sub
 
    Public Function Multiply() As Double Implements Calculation.Multiply
        WriteLine("Welcome to Interface")
        Read()
    End Function
 
End Class

The output of the above code is:

Output1.gif

Summary

Hope this article help you to Understand Interfaces and their implementation in Visual Basic.

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