VB.Net Tutorial/Class Module/Class Definition

Class declaration with a method that has a parameter

<source lang="vbnet">Module YourClassTest

  Sub Main()
     Dim obj As New YourClass
     obj.DisplayMessage("AAA")
  End Sub " Main

End Module Public Class YourClass

  Public Sub DisplayMessage(ByVal courseName As String)
     Console.WriteLine( _
        "Welcome to " & vbCrLf & courseName & "!")
  End Sub 

End Class</source>

Welcome to
AAA!

Class that contains instance variable and a property to get and set its value

<source lang="vbnet">Module YourClassTest

  Sub Main()
     Dim obj As New YourClass
     Console.WriteLine("Initial course name is: " & obj.YourName & vbCrLf)
     obj.YourName = "new Name"
     obj.DisplayMessage()
  End Sub " Mains

End Module

Public Class YourClass

  Private yourNameValue As String " course name for this YourClass
  " property YourName
  Public Property YourName() As String
     Get " retrieve yourNameValue
        Return yourNameValue
     End Get
     Set(ByVal value As String) " set yourNameValue
        yourNameValue = value " store the course name in the object
     End Set
  End Property " YourName
  " display a welcome message to the YourClass user
  Public Sub DisplayMessage()
     Console.WriteLine("Welcome to " & YourName & "!")
  End Sub " DisplayMessage

End Class</source>

Initial course name is:
Welcome to new Name!

Class with a constructor to initialize its member field value

<source lang="vbnet">Module YourClassTest

  Sub Main()
     Dim obj1 As New YourClass("AAA")
     Dim obj2 As New YourClass("BBB")
     Console.WriteLine(obj1.YourName)
     Console.WriteLine(obj2.YourName)
  End Sub " Main

End Module

Public Class YourClass

  Private yourNameValue As String " course name for this YourClass
  " constructor initializes course name with String supplied as argument
  Public Sub New(ByVal name As String)
     YourName = name " initialize yourNameValue via property
  End Sub " New
  " property YourName
  Public Property YourName() As String
     Get " retrieve yourNameValue
        Return yourNameValue
     End Get
     Set(ByVal value As String) " set yourNameValue
        yourNameValue = value " store the course name in the object
     End Set
  End Property " YourName
  Public Sub DisplayMessage()
     Console.WriteLine("Welcome to " & YourName & "!")
  End Sub " DisplayMessage

End Class " YourClass</source>

AAA
BBB

Define class

<source lang="vbnet">Option Strict On

Imports System
   Public Class YourClass
      Public weight As Integer
   End Class
   Public Class Tester
      Public Shared Sub Main( )
         Dim testObject As New Tester( )
         testObject.Run( )
      End Sub
      Public Sub Run( )
         Dim firstInt As Integer = 5
         Dim secondInt As Integer = firstInt
         Console.WriteLine("firstInt: {0} secondInt: {1}", firstInt, secondInt)
         secondInt = 7
         Console.WriteLine("firstInt: {0} secondInt: {1}", firstInt, secondInt)
         Dim obj As New YourClass( )
         obj.weight = 5
         Dim anotherObject As YourClass = obj
         Console.WriteLine("obj: {0}, anotherObject: {1}", obj.weight, anotherObject.weight)
         anotherObject.weight = 7
         Console.WriteLine( _
           "obj: {0}, anotherObject: {1}", obj.weight, anotherObject.weight)
      End Sub
   End Class</source>

firstInt: 5 secondInt: 5
firstInt: 5 secondInt: 7
obj: 5, anotherObject: 5
obj: 7, anotherObject: 7

Define your own Time Class

<source lang="vbnet">Module Tester

  Sub Main()
     Dim time As New CTime() " call CTime constructor
     Console.WriteLine("The initial universal times is: " & _
        time.ToUniversalString() & vbCrLf & _
        "The initial standard time is: " & _
        time.ToStandardString())
     time.SetTime(13, 27, 6) " set time with valid settings
     Console.WriteLine("Universal time after setTime is: " & _
        time.ToUniversalString() & vbCrLf & _
        "Standard time after setTime is: " & _
        time.ToStandardString())
     time.SetTime(99, 99, 99) " set time with invalid settings
     Console.WriteLine("Universal time: " & time.ToUniversalString() & _
        vbCrLf & "Standard time: " & time.ToStandardString())
  End Sub 

End Module Class CTime

  Inherits Object
  Private mHour As Integer " 0 - 23
  Private mMinute As Integer " 0 - 59
  Private mSecond As Integer " 0 - 59
  Public Sub New()
     SetTime(0, 0, 0)
  End Sub " New
  Public Sub SetTime(ByVal hourValue As Integer, _
     ByVal minuteValue As Integer, ByVal secondValue As Integer)
     If (hourValue >= 0 AndAlso hourValue < 24) Then
        mHour = hourValue
     Else
        mHour = 0
     End If
     If (minuteValue >= 0 AndAlso minuteValue < 60) Then
        mMinute = minuteValue
     Else
        mMinute = 0
     End If
     If (secondValue >= 0 AndAlso secondValue < 60) Then
        mSecond = secondValue
     Else
        mSecond = 0
     End If
  End Sub " SetTime
  " convert String to universal-time format
  Public Function ToUniversalString() As String
     Return String.Format("{0}:{1:D2}:{2:D2}", _
        mHour, mMinute, mSecond)
  End Function " ToUniversalString
  " convert to String in standard-time format
  Public Function ToStandardString() As String
     Dim suffix As String = " PM"
     Dim format As String = "{0}:{1:D2}:{2:D2}"
     Dim standardHour As Integer
     If mHour < 12 Then
        suffix = " AM"
     End If
     If (mHour = 12 OrElse mHour = 0) Then
        standardHour = 12
     Else
        standardHour = mHour Mod 12
     End If
     Return String.Format(format, standardHour, mMinute, _
        mSecond) & suffix
  End Function 

End Class</source>

The initial universal times is: 0:00:00
The initial standard time is: 12:00:00 AM
Universal time after setTime is: 13:27:06
Standard time after setTime is: 1:27:06 PM
Universal time: 0:00:00
Standard time: 12:00:00 AM

Implement an interface

<source lang="vbnet">Class YourClass

   Implements IFormattable
   Public Value As String
   Public Overridable Overloads Function ToString(ByVal _
     Format As String, ByVal Provider As IFormatProvider) _
     As String Implements IFormattable.ToString
       ToString = Value
   End Function
   Public Sub New(ByVal Value As String)
       Me.Value = Value
   End Sub

End Class

Module Module1

   Sub Main()
       Dim A As New YourClass("Hello VB.Net World")
       Dim S As New String("Hello")

   End Sub

End Module</source>

Overrides equals

<source lang="vbnet">Imports System Module Test

 Sub Main()
   Dim f as New Class1("Visual Basic", 1)
   Dim f2 as New Class1("Visual Basic", 1)
   Console.WriteLine(f2.Equals(f))   "True!  
   f = f2
   Console.WriteLine(f2.Equals(f))
 End Sub

End Module Public Class Class1

 Private Name as String
 Private Value as Integer
 Public Sub New(Name as String, Value as Integer)
   Me.Name = Name
   Me.Value = Value
 End Sub
 Public Overrides Function ToString() as String
   Return(Name & " has the value " & Value)
 End Function
 Public Overrides Overloads Function Equals(Obj as Object) as Boolean
   "Value equality test
   If Not IsNothing(Obj)
     If TypeOf Obj is Class1 then
       If CType(Obj, Class1).Name = Me.Name and CType(Obj, Class1).Value = Me.Value then 
         Return True
       End If
     End If
   End If
   Return False
 End Function

End Class</source>

True
True

Overrides ToString

<source lang="vbnet">Imports System Module Test

 Sub Main()
   Dim f as New Class1("A", 1)
   Dim f2 as New Class1("B", 2)
   Console.WriteLine(f)
   Console.WriteLine(f2)
 End Sub

End Module Public Class Class1

 Private Name as String
 Private Value as Integer
 Public Sub New(Name as String, Value as Integer)
   Me.Name = Name
   Me.Value = Value
 End Sub
 Public Overrides Function ToString() as String
   Return(Name & " has the value " & Value)
 End Function

End Class</source>

A has the value 1
B has the value 2

Structure and Class assignment: by reference or by value

<source lang="vbnet">public class Test

  public Shared Sub Main
       Dim cperson1 As New CPerson
       Dim cperson2 As CPerson
       cperson1.FirstName = "Alice"
       cperson2 = cperson1
       cperson2.FirstName = "Ben"
       Console.WriteLine(cperson1.FirstName & ", " & cperson2.FirstName)
       Dim sperson1 As New SPerson
       Dim sperson2 As SPerson
       sperson1.FirstName = "Alice"
       sperson2 = sperson1
       sperson2.FirstName = "Ben"
       Console.WriteLine(sperson1.FirstName & ", " & sperson2.FirstName)
  End Sub
  

End class Public Class CPerson

   Public FirstName As String
   Public LastName As String

End Class Public Structure SPerson

   Public FirstName As String
   Public LastName As String

End Structure</source>

Ben, Ben
Alice, Ben