VB.Net Tutorial/Class Module/Class Inheritance

Call base method

Option Strict On
Public Class BaseClass
   Public Sub MainMethod()
      Console.WriteLine("Calling Me.Method1...")
      Me.Method1()
      Console.WriteLine("Calling MyClass.Method1...")
      MyClass.Method1()
   End Sub
   Public Overridable Sub Method1()
      Console.WriteLine("BaseClass.Method1...")
   End Sub
End Class
Public Class DerivedClass : Inherits BaseClass
      Public Overrides Sub Method1()
         Console.WriteLine("DerivedClass.Method1...")
      End Sub
End Class
Public Module modMain
   Public Sub Main()
      Console.WriteLine("Invoking BaseClass.MainMethod")
      Dim bc As New BaseClass
      bc.MainMethod()
      Console.WriteLine()
      Console.WriteLine("Invoking DerivedClass.MainMethod")
      Dim dc As New DerivedClass
      dc.MainMethod()
   End Sub
End Module

Invoking BaseClass.MainMethod
Calling Me.Method1...
BaseClass.Method1...
Calling MyClass.Method1...
BaseClass.Method1...
Invoking DerivedClass.MainMethod
Calling Me.Method1...
DerivedClass.Method1...
Calling MyClass.Method1...
BaseClass.Method1...

Circle class that inherits from class Point

Module Tester
   Sub Main()
      Dim circle As Circle
      circle = New Circle(37, 43, 2.5) " instantiate Circle
      Console.WriteLine("X coordinate is " & circle.X & vbCrLf & _
         "Y coordinate is " & circle.Y & vbCrLf & "Radius is " & _
         circle.Radius)
      circle.X = 2
      circle.Y = 2
      circle.Radius = 4.25
      Console.WriteLine("The new location and radius of circle are " & _
         vbCrLf & circle.ToString())
      Console.WriteLine("Diameter is " & _
         String.Format("{0:F}", circle.Diameter()))
      Console.WriteLine("Circumference is " & _
         String.Format("{0:F}", circle.Circumference()))
      Console.WriteLine("Area is " & String.Format("{0:F}", circle.Area()))
   End Sub " Main
End Module 

Public Class Point
   Protected mX, mY As Integer
   Public Sub New()
      X = 0
      Y = 0
   End Sub " New
   Public Sub New(ByVal xValue As Integer, _
      ByVal yValue As Integer)
      X = xValue
      Y = yValue
   End Sub " New
   Public Property X() As Integer
      Get
         Return mX
      End Get
      Set(ByVal xValue As Integer)
         mX = xValue " no need for validation
      End Set
   End Property " X
   Public Property Y() As Integer
      Get
         Return mY
      End Get
      Set(ByVal yValue As Integer)
         mY = yValue " no need for validation
      End Set
   End Property " Y
   Public Overrides Function ToString() As String
      Return "[" & mX & ", " & mY & "]"
   End Function " ToString
End Class 

Public Class Circle
   Inherits Point " Circle Inherits from class Point
   Private mRadius As Double " Circle"s radius
   Public Sub New()
      Radius = 0
   End Sub " New
   Public Sub New(ByVal xValue As Integer, _
      ByVal yValue As Integer, ByVal radiusValue As Double)
      mX = xValue
      mY = yValue
      Radius = radiusValue
   End Sub " New
   Public Property Radius() As Double
      Get
         Return mRadius
      End Get
      Set(ByVal radiusValue As Double)
         If radiusValue > 0 Then
            mRadius = radiusValue
         End If
      End Set
   End Property " Radius
   Public Function Diameter() As Double
      Return mRadius * 2
   End Function " Diameter
   " calculate Circle circumference
   Public Function Circumference() As Double
      Return Math.PI * Diameter()
   End Function " Circumference
   " calculate Circle area
   Public Overridable Function Area() As Double
      Return Math.PI * mRadius ^ 2
   End Function " Area
   " return String representation of Circle
   Public Overrides Function ToString() As String
      Return "Center = " & "[" & mX & ", " & mY & "]" & _
         "; Radius = " & mRadius
   End Function " ToString
End Class

X coordinate is 37
Y coordinate is 43
Radius is 2.5
The new location and radius of circle are
Center = [2, 2]; Radius = 4.25
Diameter is 8.50
Circumference is 26.70
Area is 56.75

Class implicitly Inherits Object

Module Tester
   Sub Main()
      Dim point As CPoint
      point = New CPoint(2, 5) 
      Console.WriteLine("X coordinate is " & point.X & _
         vbCrLf & "Y coordinate is " & point.Y)
      point.X = 10 
      point.Y = 10 
      Console.WriteLine("The new location of point is " & point.ToString())
   End Sub " Main
End Module
Public Class CPoint
   " implicitly Inherits Object
   Private mX, mY As Integer
   Public Sub New()
      X = 0
      Y = 0
   End Sub
   
   Public Sub New(ByVal xValue As Integer,ByVal yValue As Integer)
      X = xValue
      Y = yValue
   End Sub " New
   Public Property X() As Integer
      Get
         Return mX
      End Get
      Set(ByVal xValue As Integer)
         mX = xValue " no need for validation
      End Set
   End Property " X
   Public Property Y() As Integer
      Get
         Return mY
      End Get
      Set(ByVal yValue As Integer)
         mY = yValue " no need for validation
      End Set
   End Property " Y
   Public Overrides Function ToString() As String
      Return "[" & mX & ", " & mY & "]"
   End Function " ToString
End Class

X coordinate is 2
Y coordinate is 5
The new location of point is [10, 10]

Class inheritance and polymorphism

Imports System.Collections
public class Test
   public Shared Sub Main
        Dim objShape1 As New Triangle
        Dim objShape2 As New Circle
        Dim objShape3 As New Square
        Dim ShapeEnum As IEnumerator
        Dim dblTotalArea As Double
        objShape1.SideA = 3
        objShape1.SideB = 3.2
        objShape1.SideC = 0.94
        Console.WriteLine("The triangle"s area is " & objShape1.Area.ToString & ".")
        objShape2.Radius = 4
        Console.WriteLine("The circle"s area is " & objShape2.Area.ToString & ".")
        objShape3.Side = 10.01
        Console.WriteLine("The square"s area is " & objShape3.Area.ToString & ".")
        Dim aryShapes() As Shape = {objShape1, objShape2, objShape3}
        ShapeEnum = aryShapes.GetEnumerator
        While ShapeEnum.MoveNext
            dblTotalArea += CType(ShapeEnum.Current, Shape).Area
        End While
        Console.WriteLine("The total area of your shapes is " & dblTotalArea.ToString & ".")
   End Sub
End class
Public MustInherit Class Shape
    Public MustOverride Function Area() As Double
    Public MustOverride Function Perimeter() As Double
End Class

Public Class Square
    Inherits Shape
    Private mySide As Double
    Public Property Side() As Double
        Get
            Side = mySide
        End Get
        Set(ByVal Value As Double)
            mySide = Value
        End Set
    End Property
    Public Overrides Function Area() As Double
        Area = mySide * mySide
    End Function
    Public Overrides Function Perimeter() As Double
        Return (4 * mySide)
    End Function
End Class
Public Class Triangle
    Inherits Shape
    Private mySide1, mySide2, mySide3 As Double
    Property SideA() As Double
        Get
            SideA = mySide1
        End Get
        Set(ByVal Value As Double)
            mySide1 = Value
        End Set
    End Property
    Property SideB() As Double
        Get
            SideB = mySide2
        End Get
        Set(ByVal Value As Double)
            mySide2 = Value
        End Set
    End Property
    Public Property SideC() As Double
        Get
            SideC = mySide3
        End Get
        Set(ByVal Value As Double)
            mySide3 = Value
        End Set
    End Property
    Public Overrides Function Area() As Double
        Dim dblPerim As Double
        dblPerim = Perimeter()
        Return (Math.Sqrt(dblPerim * (dblPerim - mySide1) * _
        (dblPerim - mySide2) * (dblPerim - mySide3)))
    End Function
    Public Overrides Function Perimeter() As Double
        Return (mySide1 + mySide2 + mySide3)
    End Function
    Sub New(ByVal SideA As Double, ByVal SideB As Double, ByVal SideC As Double)
        MyBase.New()
        mySide1 = SideA
        mySide2 = SideB
        mySide3 = SideC
    End Sub
    Sub New()
        MyBase.New()
    End Sub
End Class
Public Class Circle
    Inherits Shape
    Private m_dblRadius As Double
    Public Property Radius() As Double
        Get
            Radius = m_dblRadius
        End Get
        Set(ByVal Value As Double)
            m_dblRadius = Value
        End Set
    End Property
    Public Overrides Function Area() As Double
        Return (Math.PI * m_dblRadius ^ 2)
    End Function
    Public Overrides Function Perimeter() As Double
        Return (2 * Math.PI * m_dblRadius)
    End Function
    Sub New()
        MyBase.New()
    End Sub
    Sub New(ByVal Radius As Double)
        MyBase.New()
        m_dblRadius = Radius
    End Sub
End Class

The triangle"s area is 26.8715818068085.
The circle"s area is 50.2654824574367.
The square"s area is 100.2001.
The total area of your shapes is 177.337164264245.

Inherit constant from base class

Public Class ConstantBase
   Public Const GENERATION As Integer = 1
End Class
Public Class ConstantDerived : Inherits ConstantBase
End Class
Public Class classMain
   Public Shared Sub Main()
       Dim cd As New ConstantDerived
       Console.WriteLine(cd.GENERATION)
   End Sub
End Class

1

Inherit ToString method from Object

Option Strict On
Public Class EmptyClass
End Class
Public Module modMain
   Public Sub Main()
      Dim ec As New EmptyClass
      Console.WriteLine(ec.ToString()) 
   End Sub
End Module

EmptyClass

Multilevel inheritance

Class Person
    Public Name As String
    Public Age As Integer
    Public Sub New(ByVal Name As String, ByVal Age As Integer)
        Me.Name = Name
        Me.Age = Age
    End Sub
End Class
Class Player
    Inherits Person
    Public Sport As String
    Public Team As String
    Public Sub New(ByVal Name As String, ByVal Age As Integer, _
    ByVal Sport As String, ByVal Team As String)
        MyBase.New(Name, Age)
        Me.Team = Team
        Me.Sport = Sport
    End Sub
End Class
Class BasketPlayer
    Inherits Player
    Public PointsPerGame As Double
    Public Rebounds As Double
    Public Sub New(ByVal Name As String, ByVal Age As Integer, _
    ByVal Sport As String, ByVal Team As String, ByVal Points As Double, ByVal Rebounds As Double)
        MyBase.New(Name, Age, Sport, Team)
        Me.PointsPerGame = Points
        Me.Rebounds = Rebounds
    End Sub
    Public Sub Show()
        Console.WriteLine("Player: " & Name)
        Console.WriteLine("Age: " & Age)
        Console.WriteLine("Sport: " & Sport)
        Console.WriteLine("Team: " & Team)
        Console.WriteLine("Points: " & PointsPerGame)
        Console.WriteLine("Rebounds: " & Rebounds)
    End Sub
End Class
Module Module1
    Sub Main()
        Dim K As New BasketPlayer("AA", 12, "Basketball", "Team", 25.5, 6.3)
        K.Show()
    End Sub
End Module

Player: AA
Age: 12
Sport: Basketball
Team: Team
Points: 25.5
Rebounds: 6.3

Shadows member function from base class

Option Strict On
Public Class ShadowClass
   Private value As String
   Public Sub New(value As String)
      Me.value = value
   End Sub
   Public Shadows Function ToString() As String
      Return "Value of " & Me.GetType.Name & ": " & Me.value
   End Function
End Class
Public Module ShadowTest
   Public Sub Main()
      Dim sc As ShadowClass = New ShadowClass("The Shadow")
      Console.WriteLine(sc.ToString())
      Dim obj As Object = New ShadowClass("The Shadow")
      Console.WriteLine(obj.ToString())
   End Sub
End Module

Value of ShadowClass: The Shadow
ShadowClass

Simple Inheritance

Public Class Tester
    Public Shared Sub Main
        Dim objJohn As New John
        objJohn.Walk()
    End Sub
End Class

Public Class Person
    Public Sub Walk()
        Console.WriteLine("Walking...")
    End Sub
End Class
Class John
    Inherits Person
End Class

Walking...

Use For Each for Class Hierarchy

public class Test
   public Shared Sub Main
        Dim people As New Collection
        people.Add(New Employee("A"))
        people.Add(New Customer("B"))
        For Each person As Object In people
            Console.WriteLine(person.Name)
        Next person
   End Sub
End class

Public Class Employee
    Public Name As String
    Public Sub New(ByVal new_name As String)
        Name = new_name
    End Sub
    Public Overridable Function IsManager() As Boolean
        Return False
    End Function
End Class
Public Class Customer
    Public Name As String
    Public Sub New(ByVal new_name As String)
        Name = new_name
    End Sub
End Class
Public Class Manager
    Inherits Employee
    Public Sub New(ByVal new_name As String)
        MyBase.new(new_name)
    End Sub
    Public Overrides Function IsManager() As Boolean
        Return True
    End Function
End Class

A
B