VB.Net Tutorial/Class Module/Class Definition

Содержание

1 Class declaration with a method that has a parameter
2 Class that contains instance variable and a property to get and set its value
3 Class with a constructor to initialize its member field value
4 Define class
5 Define your own Time Class
6 Implement an interface
7 Overrides equals
8 Overrides ToString
9 Structure and Class assignment: by reference or by value

Class declaration with a method that has a parameter

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

Welcome to
AAA!

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

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

Initial course name is:
Welcome to new Name!

Class with a constructor to initialize its member field value

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

AAA
BBB

Define class

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

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

Define your own Time Class

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

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

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

Overrides equals

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

True
True

Overrides ToString

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

A has the value 1
B has the value 2

Structure and Class assignment: by reference or by value

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

Ben, Ben
Alice, Ben

VB.Net Tutorial/Class Module/Class Definition

Содержание

Class declaration with a method that has a parameter

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

Class with a constructor to initialize its member field value

Define class

Define your own Time Class

Implement an interface

Overrides equals

Overrides ToString

Structure and Class assignment: by reference or by value

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