Interfaces

In VB.NET, an interface is a contract that specifies a set of members that a class must implement. To define an interface in VB.NET, we use the Interface keyword. A class that implements an interface must implement all the members defined in that interface.

Example:

vb.netCopy codeInterface IShape
    ReadOnly Property Area As Double
    ReadOnly Property Perimeter As Double
End Interface

Class Rectangle
    Implements IShape
    
    Private _length As Double
    Private _width As Double
    
    Public Sub New(ByVal length As Double, ByVal width As Double)
        Me._length = length
        Me._width = width
    End Sub
    
    Public ReadOnly Property Area As Double Implements IShape.Area
        Get
            Return Me._length * Me._width
        End Get
    End Property
    
    Public ReadOnly Property Perimeter As Double Implements IShape.Perimeter
        Get
            Return 2 * (Me._length + Me._width)
        End Get
    End Property
End Class

' Create an object of the Rectangle class and access its properties
Dim rectangle As New Rectangle(5, 10)
Console.WriteLine(rectangle.Area)
Console.WriteLine