VB.Net Tutorial/Event/Event
Содержание
- 1 Add and remove event handler
- 2 Add, remove event handler to/from ToggleButton
- 3 Custom event handler
- 4 Event handler
- 5 Get event sender type
- 6 Handle events from more than one components
- 7 Inherit Event
- 8 Multiple Event Handler
- 9 Raise Events
- 10 Subclass EventArgs to create your own event arguments
- 11 Use one method to handle more than one RadioButton click event
- 12 WithEvents and Event method
Add and remove event handler
<source lang="vbnet">Imports System.Windows.Forms public class AddRemoveEventHandler
public Shared Sub Main
Application.Run(New Form1)
End Sub
End class
Public Class Form1
Private Sub RadioButton1_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton1.CheckedChanged
If RadioButton1.Checked Then
AddHandler Button1.Click, AddressOf ButtonHandler1
Else
RemoveHandler Button1.Click, AddressOf ButtonHandler1
End If
End Sub
Private Sub RadioButton2_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles RadioButton2.CheckedChanged
If RadioButton2.Checked Then
AddHandler Button1.Click, AddressOf ButtonHandler2
Else
RemoveHandler Button1.Click, AddressOf ButtonHandler2
End If
End Sub
Private Sub ButtonHandler1(ByVal sender As System.Object, ByVal e As System.EventArgs)
MessageBox.Show("ButtonHandler1")
End Sub
Private Sub ButtonHandler2(ByVal sender As System.Object, ByVal e As System.EventArgs)
MessageBox.Show("ButtonHandler2")
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
RadioButton1.Checked = True
End Sub
End Class <Global.Microsoft.VisualBasic.rupilerServices.DesignerGenerated()> _ Partial Public Class Form1
Inherits System.Windows.Forms.Form
"Form overrides dispose to clean up the component list.
<System.Diagnostics.DebuggerNonUserCode()> _
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing AndAlso components IsNot Nothing Then
components.Dispose()
End If
MyBase.Dispose(disposing)
End Sub
"Required by the Windows Form Designer
Private components As System.ruponentModel.IContainer
"NOTE: The following procedure is required by the Windows Form Designer
"It can be modified using the Windows Form Designer.
"Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> _
Private Sub InitializeComponent()
Me.RadioButton1 = New System.Windows.Forms.RadioButton
Me.RadioButton2 = New System.Windows.Forms.RadioButton
Me.Button1 = New System.Windows.Forms.Button
Me.SuspendLayout()
"
"RadioButton1
"
Me.RadioButton1.AutoSize = True
Me.RadioButton1.Location = New System.Drawing.Point(8, 8)
Me.RadioButton1.Name = "RadioButton1"
Me.RadioButton1.Size = New System.Drawing.Size(99, 17)
Me.RadioButton1.TabIndex = 0
Me.RadioButton1.Text = "ButtonHandler1"
Me.RadioButton1.UseVisualStyleBackColor = True
"
"RadioButton2
"
Me.RadioButton2.AutoSize = True
Me.RadioButton2.Location = New System.Drawing.Point(8, 40)
Me.RadioButton2.Name = "RadioButton2"
Me.RadioButton2.Size = New System.Drawing.Size(99, 17)
Me.RadioButton2.TabIndex = 1
Me.RadioButton2.Text = "ButtonHandler2"
Me.RadioButton2.UseVisualStyleBackColor = True
"
"Button1
"
Me.Button1.Location = New System.Drawing.Point(152, 16)
Me.Button1.Name = "Button1"
Me.Button1.Size = New System.Drawing.Size(75, 23)
Me.Button1.TabIndex = 2
Me.Button1.Text = "Button1"
Me.Button1.UseVisualStyleBackColor = True
"
"Form1
"
Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
Me.ClientSize = New System.Drawing.Size(292, 273)
Me.Controls.Add(Me.Button1)
Me.Controls.Add(Me.RadioButton2)
Me.Controls.Add(Me.RadioButton1)
Me.Name = "Form1"
Me.Text = "AddRemoveHandler"
Me.ResumeLayout(False)
Me.PerformLayout()
End Sub
Friend WithEvents RadioButton1 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton2 As System.Windows.Forms.RadioButton
Friend WithEvents Button1 As System.Windows.Forms.Button
End Class</source>
Add, remove event handler to/from ToggleButton
<source lang="vbnet">Imports System.Windows.Forms public class AddHandlerAndRemoveHandlerForToggleButton
public Shared Sub Main
Application.Run(New Form1)
End Sub
End class Public Class Form1
Inherits System.Windows.Forms.Form
- Region " Windows Form Designer generated code "
Public Sub New()
MyBase.New()
"This call is required by the Windows Form Designer.
InitializeComponent()
"Add any initialization after the InitializeComponent() call
End Sub
"Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
"Required by the Windows Form Designer
Private components As System.ruponentModel.IContainer
"NOTE: The following procedure is required by the Windows Form Designer
"It can be modified using the Windows Form Designer.
"Do not modify it using the code editor.
Friend WithEvents Button1 As System.Windows.Forms.Button
Friend WithEvents CheckBox1 As System.Windows.Forms.CheckBox
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.Button1 = New System.Windows.Forms.Button
Me.CheckBox1 = New System.Windows.Forms.CheckBox
Me.SuspendLayout()
"
"Button1
"
Me.Button1.Location = New System.Drawing.Point(40, 32)
Me.Button1.Name = "Button1"
Me.Button1.TabIndex = 0
Me.Button1.Text = "Click Me!"
"
"CheckBox1
"
Me.CheckBox1.Appearance = System.Windows.Forms.Appearance.Button
Me.CheckBox1.Checked = True
Me.CheckBox1.CheckState = System.Windows.Forms.CheckState.Checked
Me.CheckBox1.Location = New System.Drawing.Point(136, 31)
Me.CheckBox1.Name = "CheckBox1"
Me.CheckBox1.Size = New System.Drawing.Size(128, 24)
Me.CheckBox1.TabIndex = 1
Me.CheckBox1.Text = "Toggle Event Handling"
Me.CheckBox1.TextAlign = System.Drawing.ContentAlignment.MiddleCenter
"
"Form1
"
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(292, 273)
Me.Controls.Add(Me.CheckBox1)
Me.Controls.Add(Me.Button1)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
- End Region
Private Sub CheckBox1_CheckedChanged( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles CheckBox1.CheckedChanged
If CheckBox1.Checked Then
AddHandler Button1.Click, _
AddressOf myClickHandler
Else
RemoveHandler Button1.Click, _
AddressOf myClickHandler
End If
End Sub
Private Sub myClickHandler( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs)
MsgBox("Event Handled!")
End Sub
End Class</source>
Custom event handler
<source lang="vbnet">Imports System.Collections Delegate Sub NameChangedDelegate(ByVal new_name As String) public class Test
Private WithEvents emp As Employee
public Shared Sub Main
Dim emp As New Employee
AddHandler emp.NameChanged, AddressOf Employee_NameChanged
AddHandler emp.NameChanged, AddressOf Employee_NameChanged
emp.FirstName = "Rod"
RemoveHandler emp.NameChanged, AddressOf Employee_NameChanged
emp.LastName = "Stephens"
RemoveHandler emp.NameChanged, AddressOf Employee_NameChanged
End Sub
Private Shared Sub Employee_NameChanged(ByVal new_name As String) Handles emp.NameChanged
Console.WriteLine("Employee_NameChanged: " & new_name)
End Sub
End class Public Class Employee
Private m_FirstName As String
Public Property FirstName() As String
Get
Return m_FirstName
End Get
Set(ByVal value As String)
m_FirstName = value
RaiseEvent NameChanged(m_FirstName & " " & m_LastName)
End Set
End Property
Private m_LastName As String
Public Property LastName() As String
Get
Return m_LastName
End Get
Set(ByVal value As String)
m_LastName = value
RaiseEvent NameChanged(m_FirstName & " " & m_LastName)
End Set
End Property
Private m_EventDelegates As New ArrayList
Public Delegate Sub NameChangedDelegate(ByVal new_name As String)
Public Custom Event NameChanged As NameChangedDelegate
AddHandler(ByVal value As NameChangedDelegate)
Console.WriteLine("AddHandler")
m_EventDelegates.Add(value)
End AddHandler
RemoveHandler(ByVal value As NameChangedDelegate)
Console.WriteLine("RemoveHandler")
m_EventDelegates.Remove(value)
End RemoveHandler
RaiseEvent(ByVal new_name As String)
Console.WriteLine("RaiseEvent (" & new_name & ")")
For Each a_delegate As NameChangedDelegate In m_EventDelegates
a_delegate(new_name.Replace(" ", "+"))
Next a_delegate
End RaiseEvent
End Event
End Class</source>
AddHandler AddHandler RaiseEvent (Rod ) Employee_NameChanged: Rod+ Employee_NameChanged: Rod+ RemoveHandler RaiseEvent (Rod Stephens) Employee_NameChanged: Rod+Stephens RemoveHandler
Event handler
<source lang="vbnet">Module Module1
Class Job
Public Event Meeting()
Public Event Testing(ByVal Temp As Integer)
Public Event Coding(ByVal Room As String, ByVal Duration As Integer)
Public Sub GenerateEvents()
RaiseEvent Meeting()
RaiseEvent Testing(212)
RaiseEvent Coding("VB.net", 25)
End Sub
End Class
Dim WithEvents Alarms As New Job()
Sub MyMeeting() Handles Alarms.Meeting
Console.WriteLine("MyMeeting alarm occurred")
End Sub
Sub MyTesting(ByVal Temp As Integer) Handles Alarms.Testing
Console.WriteLine("MyTesting alarm occurred: Temp: " & Temp)
End Sub
Sub MyCoding(ByVal Room As String, ByVal Duration As Integer) Handles Alarms.Coding
Console.WriteLine("MyCoding alarm occurred: " & Room & " " & Duration)
End Sub
Sub Main()
Alarms.GenerateEvents()
End Sub
End Module</source>
MyMeeting alarm occurred MyTesting alarm occurred: Temp: 212 MyCoding alarm occurred: VB.net 25
Get event sender type
<source lang="vbnet">Imports System.Windows.Forms public class TypeOfSenderIsControl
public Shared Sub Main
Application.Run(New Form1)
End Sub
End class
Public Class Form1
Inherits System.Windows.Forms.Form
- Region " Windows Form Designer generated code "
Public Sub New()
MyBase.New()
"This call is required by the Windows Form Designer.
InitializeComponent()
"Add any initialization after the InitializeComponent() call
End Sub
"Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
"Required by the Windows Form Designer
Private components As System.ruponentModel.IContainer
"NOTE: The following procedure is required by the Windows Form Designer
"It can be modified using the Windows Form Designer.
"Do not modify it using the code editor.
Friend WithEvents Button1 As System.Windows.Forms.Button
Friend WithEvents Button2 As System.Windows.Forms.Button
Friend WithEvents Button3 As System.Windows.Forms.Button
Friend WithEvents Button4 As System.Windows.Forms.Button
Friend WithEvents Button5 As System.Windows.Forms.Button
Friend WithEvents Button6 As System.Windows.Forms.Button
Friend WithEvents Button7 As System.Windows.Forms.Button
Friend WithEvents Button8 As System.Windows.Forms.Button
Friend WithEvents Button9 As System.Windows.Forms.Button
Friend WithEvents Button10 As System.Windows.Forms.Button
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.Button1 = New System.Windows.Forms.Button
Me.Button2 = New System.Windows.Forms.Button
Me.Button3 = New System.Windows.Forms.Button
Me.Button4 = New System.Windows.Forms.Button
Me.Button5 = New System.Windows.Forms.Button
Me.Button6 = New System.Windows.Forms.Button
Me.Button7 = New System.Windows.Forms.Button
Me.Button8 = New System.Windows.Forms.Button
Me.Button9 = New System.Windows.Forms.Button
Me.Button10 = New System.Windows.Forms.Button
Me.SuspendLayout()
"
"Button1
"
Me.Button1.Location = New System.Drawing.Point(80, 16)
Me.Button1.Name = "Button1"
Me.Button1.TabIndex = 0
Me.Button1.Text = "Button1"
"
"Button2
"
Me.Button2.Location = New System.Drawing.Point(80, 48)
Me.Button2.Name = "Button2"
Me.Button2.TabIndex = 1
Me.Button2.Text = "Button2"
"
"Button3
"
Me.Button3.Location = New System.Drawing.Point(80, 80)
Me.Button3.Name = "Button3"
Me.Button3.TabIndex = 2
Me.Button3.Text = "Button3"
"
"Button4
"
Me.Button4.Location = New System.Drawing.Point(80, 112)
Me.Button4.Name = "Button4"
Me.Button4.TabIndex = 3
Me.Button4.Text = "Button4"
"
"Button5
"
Me.Button5.Location = New System.Drawing.Point(80, 144)
Me.Button5.Name = "Button5"
Me.Button5.TabIndex = 4
Me.Button5.Text = "Button5"
"
"Button6
"
Me.Button6.Location = New System.Drawing.Point(168, 16)
Me.Button6.Name = "Button6"
Me.Button6.TabIndex = 5
Me.Button6.Text = "Button6"
"
"Button7
"
Me.Button7.Location = New System.Drawing.Point(168, 48)
Me.Button7.Name = "Button7"
Me.Button7.TabIndex = 6
Me.Button7.Text = "Button7"
"
"Button8
"
Me.Button8.Location = New System.Drawing.Point(168, 80)
Me.Button8.Name = "Button8"
Me.Button8.TabIndex = 7
Me.Button8.Text = "Button8"
"
"Button9
"
Me.Button9.Location = New System.Drawing.Point(168, 112)
Me.Button9.Name = "Button9"
Me.Button9.TabIndex = 8
Me.Button9.Text = "Button9"
"
"Button10
"
Me.Button10.Location = New System.Drawing.Point(168, 144)
Me.Button10.Name = "Button10"
Me.Button10.TabIndex = 9
Me.Button10.Text = "Button10"
"
"Form1
"
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(292, 273)
Me.Controls.Add(Me.Button10)
Me.Controls.Add(Me.Button9)
Me.Controls.Add(Me.Button8)
Me.Controls.Add(Me.Button7)
Me.Controls.Add(Me.Button6)
Me.Controls.Add(Me.Button5)
Me.Controls.Add(Me.Button4)
Me.Controls.Add(Me.Button3)
Me.Controls.Add(Me.Button2)
Me.Controls.Add(Me.Button1)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
- End Region
Private Sub Button1_Click( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button1.Click
MsgBox("Hello World!")
End Sub
Private Sub LotsOfButtons( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles Button1.Click, Button2.Click, _
Button3.Click, Button4.Click, _
Button5.Click, Button6.Click, _
Button7.Click, Button8.Click, _
Button9.Click, Button10.Click
Dim clickedCtrl As Control
If TypeOf sender Is Control Then
clickedCtrl = DirectCast(sender, Control)
Console.WriteLine(clickedCtrl.Text)
End If
End Sub
End Class</source>
Handle events from more than one components
<source lang="vbnet">Imports System.Windows.Forms public class EventHandlerForMoreThanOneComponent
public Shared Sub Main
Application.Run(New Form1)
End Sub
End class Public Class Form1
Inherits System.Windows.Forms.Form
- Region " Windows Form Designer generated code "
Public Sub New()
MyBase.New()
"This call is required by the Windows Form Designer.
InitializeComponent()
"Add any initialization after the InitializeComponent() call
End Sub
"Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
"Required by the Windows Form Designer
Private components As System.ruponentModel.IContainer
"NOTE: The following procedure is required by the Windows Form Designer
"It can be modified using the Windows Form Designer.
"Do not modify it using the code editor.
Friend WithEvents ImageList1 As System.Windows.Forms.ImageList
Friend WithEvents txtFirstName As System.Windows.Forms.TextBox
Friend WithEvents txtLastName As System.Windows.Forms.TextBox
Friend WithEvents txtEmail As System.Windows.Forms.TextBox
Friend WithEvents lblFirstName As System.Windows.Forms.Label
Friend WithEvents lblLastName As System.Windows.Forms.Label
Friend WithEvents lblEmail As System.Windows.Forms.Label
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.ruponents = New System.ruponentModel.Container()
Me.txtFirstName = New System.Windows.Forms.TextBox()
Me.txtLastName = New System.Windows.Forms.TextBox()
Me.txtEmail = New System.Windows.Forms.TextBox()
Me.lblFirstName = New System.Windows.Forms.Label()
Me.lblLastName = New System.Windows.Forms.Label()
Me.lblEmail = New System.Windows.Forms.Label()
Me.SuspendLayout()
"
"txtFirstName
"
Me.txtFirstName.Location = New System.Drawing.Point(80, 32)
Me.txtFirstName.Name = "txtFirstName"
Me.txtFirstName.Size = New System.Drawing.Size(152, 20)
Me.txtFirstName.TabIndex = 1
Me.txtFirstName.Text = ""
"
"txtLastName
"
Me.txtLastName.Location = New System.Drawing.Point(80, 56)
Me.txtLastName.Name = "txtLastName"
Me.txtLastName.Size = New System.Drawing.Size(152, 20)
Me.txtLastName.TabIndex = 2
Me.txtLastName.Text = ""
"
"txtEmail
"
Me.txtEmail.Location = New System.Drawing.Point(80, 80)
Me.txtEmail.Name = "txtEmail"
Me.txtEmail.Size = New System.Drawing.Size(224, 20)
Me.txtEmail.TabIndex = 3
Me.txtEmail.Text = ""
"
"lblFirstName
"
Me.lblFirstName.AutoSize = True
Me.lblFirstName.Location = New System.Drawing.Point(8, 32)
Me.lblFirstName.Name = "lblFirstName"
Me.lblFirstName.Size = New System.Drawing.Size(59, 13)
Me.lblFirstName.TabIndex = 4
Me.lblFirstName.Text = "First Name"
"
"lblLastName
"
Me.lblLastName.AutoSize = True
Me.lblLastName.Location = New System.Drawing.Point(8, 56)
Me.lblLastName.Name = "lblLastName"
Me.lblLastName.Size = New System.Drawing.Size(59, 13)
Me.lblLastName.TabIndex = 5
Me.lblLastName.Text = "Last Name"
"
"lblEmail
"
Me.lblEmail.AutoSize = True
Me.lblEmail.Location = New System.Drawing.Point(8, 80)
Me.lblEmail.Name = "lblEmail"
Me.lblEmail.Size = New System.Drawing.Size(33, 13)
Me.lblEmail.TabIndex = 6
Me.lblEmail.Text = "Email"
"
"Form1
"
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(312, 125)
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.lblEmail, Me.lblLastName, Me.lblFirstName, Me.txtEmail, Me.txtLastName, Me.txtFirstName})
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
- End Region
Private Sub Names_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtFirstName.TextChanged, txtLastName.TextChanged
txtEmail.Text = txtFirstName.Text & "." & txtLastName.Text
End Sub
End Class</source>
Inherit Event
<source lang="vbnet">Module Module1
Public Class DailyEvents
Public Event Meeting(ByVal Item As String,ByVal StartTime As String)
Public Event Coding(ByVal Item As String,ByVal StartTime As String)
Public Event Testing(ByVal Item As String,ByVal StartTime As String)
Public Sub GenerateEvents()
RaiseEvent Meeting("A", "9:30AM")
RaiseEvent Meeting("B", "11:30AM")
RaiseEvent Meeting("C", "2:30PM")
RaiseEvent Coding("D", "12:30PM")
RaiseEvent Testing("E", "5:30PM")
End Sub
End Class
Public Class TodaysActivities
Inherits DailyEvents
Public StartDay As DateTime
Public EndDay As DateTime
Public Sub New(ByVal StartDay As DateTime, ByVal EndDay As DateTime)
MyBase.New()
Me.StartDay = StartDay
Me.EndDay = EndDay
End Sub
End Class
Dim WithEvents Today As New TodaysActivities(Now(), Now.AddHours(8))
Sub ScheduleHandler(ByVal Item As String,ByVal StartTime As String)
Console.WriteLine(Item & " at: " & StartTime)
End Sub
Sub Main()
AddHandler Today.Meeting, AddressOf ScheduleHandler
AddHandler Today.Coding, AddressOf ScheduleHandler
AddHandler Today.Testing, AddressOf ScheduleHandler
Today.GenerateEvents()
End Sub
End Module</source>
A at: 9:30AM B at: 11:30AM C at: 2:30PM D at: 12:30PM E at: 5:30PM
Multiple Event Handler
<source lang="vbnet">Module Module1
Class DailyJob
Public Event Coding(ByVal Item As String, ByVal StartTime As DateTime)
Public Event Testing(ByVal Item As String, ByVal StartTime As DateTime)
Public Event Meeting(ByVal Item As String, ByVal StartTime As DateTime)
Public Sub GenerateEvents()
RaiseEvent Coding("coding", Now())
RaiseEvent Testing("testing", Now().AddMinutes(5.0))
RaiseEvent Meeting("meeting", Now.AddMinutes(10.0))
End Sub
End Class
Dim WithEvents ThisDailyJob As New DailyJob()
Sub DoJob(ByVal Item As String, ByVal StartTime As DateTime)
Console.WriteLine("Starting " & Item & " at: " & StartTime)
End Sub
Sub Main()
AddHandler ThisDailyJob.Coding, AddressOf DoJob
AddHandler ThisDailyJob.Testing, AddressOf DoJob
AddHandler ThisDailyJob.Meeting, AddressOf DoJob
ThisDailyJob.GenerateEvents()
End Sub
End Module</source>
Starting coding at: 11/05/2007 9:33:45 PM Starting testing at: 11/05/2007 9:38:45 PM Starting meeting at: 11/05/2007 9:43:45 PM
Raise Events
<source lang="vbnet">Module Module1
Dim WithEvents ValueInfo As New Value()
Class Value
Public Event ValueUp(ByVal Amount As Double)
Public Event ValueDown(ByVal Amount As Double)
Public Event Result(ByVal Amount As Double, ByVal AnnounceDate As DateTime)
Public Sub GenerateEvents()
RaiseEvent ValueUp(2)
RaiseEvent ValueDown(-5.5)
RaiseEvent Result(1.25, Now())
End Sub
End Class
Sub PriceGoingUp(ByVal Price As Double)
Console.WriteLine("Up: " & Price)
End Sub
Sub PriceGoingDown(ByVal Price As Double)
Console.WriteLine("Down: " & Price)
End Sub
Sub ResultAnnouncement(ByVal Amount As Double, ByVal AnnounceDate As DateTime)
Console.WriteLine("Result: " & Amount & " " & AnnounceDate)
End Sub
Sub Main()
AddHandler ValueInfo.ValueUp, AddressOf PriceGoingUp
AddHandler ValueInfo.ValueDown, AddressOf PriceGoingDown
AddHandler ValueInfo.Result, AddressOf ResultAnnouncement
ValueInfo.GenerateEvents()
End Sub
End Module</source>
Up: 2 Down: -5.5 Result: 1.25 11/05/2007 9:33:43 PM
Subclass EventArgs to create your own event arguments
<source lang="vbnet">Module Module1
Class MyEventArgs
Inherits System.EventArgs
Public Message As String
Public Time As DateTime
Public Sub New(ByVal S As String, ByVal DT As DateTime)
MyBase.New()
Message = S
Time = DT
End Sub
End Class
Class MyMonitor
Public Event EventStart(ByVal E As Object, ByVal Args As MyEventArgs)
Public Sub GenerateEvent()
Dim Args As New MyEventArgs("Hacker, Hacker", Now())
RaiseEvent EventStart(Me, Args)
End Sub
End Class
Dim WithEvents HackerAlarm As New MyMonitor()
Sub Attack(ByVal O As Object, ByVal Args As MyEventArgs) Handles HackerAlarm.EventStart
Console.WriteLine("Hack Attack in progress")
Console.WriteLine(Args.Message)
Console.WriteLine(Args.Time)
End Sub
Sub Main()
HackerAlarm.GenerateEvent()
End Sub
End Module</source>
Hack Attack in progress Hacker, Hacker 11/05/2007 9:33:47 PM
Use one method to handle more than one RadioButton click event
<source lang="vbnet">Imports System.Windows.Forms public class HandlerMoreThanOneRadioButtonEventWithOneMethod
public Shared Sub Main
Application.Run(New Form1)
End Sub
End class Public Class Form1
Inherits System.Windows.Forms.Form Dim radioButtons(4) As RadioButton Dim selectedOption As Integer = 0
- Region " Windows Form Designer generated code "
Public Sub New()
MyBase.New()
"This call is required by the Windows Form Designer.
InitializeComponent()
"Add any initialization after the InitializeComponent() call
radioButtons(0) = RadioButton1
radioButtons(1) = RadioButton2
radioButtons(2) = RadioButton3
radioButtons(3) = RadioButton4
radioButtons(4) = RadioButton5
End Sub
"Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
"Required by the Windows Form Designer
Private components As System.ruponentModel.IContainer
"NOTE: The following procedure is required by the Windows Form Designer
"It can be modified using the Windows Form Designer.
"Do not modify it using the code editor.
Friend WithEvents RadioButton1 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton2 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton3 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton4 As System.Windows.Forms.RadioButton
Friend WithEvents RadioButton5 As System.Windows.Forms.RadioButton
Friend WithEvents Label1 As System.Windows.Forms.Label
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
Me.RadioButton1 = New System.Windows.Forms.RadioButton
Me.RadioButton2 = New System.Windows.Forms.RadioButton
Me.RadioButton3 = New System.Windows.Forms.RadioButton
Me.RadioButton4 = New System.Windows.Forms.RadioButton
Me.RadioButton5 = New System.Windows.Forms.RadioButton
Me.Label1 = New System.Windows.Forms.Label
Me.SuspendLayout()
"
"RadioButton1
"
Me.RadioButton1.Location = New System.Drawing.Point(118, 64)
Me.RadioButton1.Name = "RadioButton1"
Me.RadioButton1.TabIndex = 0
Me.RadioButton1.Text = "RadioButton1"
"
"RadioButton2
"
Me.RadioButton2.Location = New System.Drawing.Point(118, 88)
Me.RadioButton2.Name = "RadioButton2"
Me.RadioButton2.TabIndex = 1
Me.RadioButton2.Text = "RadioButton2"
"
"RadioButton3
"
Me.RadioButton3.Location = New System.Drawing.Point(118, 112)
Me.RadioButton3.Name = "RadioButton3"
Me.RadioButton3.TabIndex = 2
Me.RadioButton3.Text = "RadioButton3"
"
"RadioButton4
"
Me.RadioButton4.Location = New System.Drawing.Point(118, 136)
Me.RadioButton4.Name = "RadioButton4"
Me.RadioButton4.TabIndex = 3
Me.RadioButton4.Text = "RadioButton4"
"
"RadioButton5
"
Me.RadioButton5.Location = New System.Drawing.Point(118, 160)
Me.RadioButton5.Name = "RadioButton5"
Me.RadioButton5.TabIndex = 4
Me.RadioButton5.Text = "RadioButton5"
"
"Label1
"
Me.Label1.Location = New System.Drawing.Point(40, 24)
Me.Label1.Name = "Label1"
Me.Label1.TabIndex = 5
Me.Label1.Text = "Label1"
"
"Form1
"
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(292, 266)
Me.Controls.Add(Me.Label1)
Me.Controls.Add(Me.RadioButton5)
Me.Controls.Add(Me.RadioButton4)
Me.Controls.Add(Me.RadioButton3)
Me.Controls.Add(Me.RadioButton2)
Me.Controls.Add(Me.RadioButton1)
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
- End Region
Private Sub RadioButton1_CheckedChanged( _
ByVal sender As System.Object, _
ByVal e As System.EventArgs) _
Handles RadioButton1.CheckedChanged, _
RadioButton2.CheckedChanged, _
RadioButton3.CheckedChanged, _
RadioButton4.CheckedChanged, _
RadioButton5.CheckedChanged
Dim i As Integer = 0
Dim found As Boolean = False
While i < 5 And Not found
If radioButtons(i).Checked Then
found = True
selectedOption = i + 1
Label1.Text = CStr(selectedOption)
End If
i += 1
End While
End Sub
End Class</source>
WithEvents and Event method
<source lang="vbnet">Public Class Tester
Shared Dim WithEvents Click3 As New TripleClicker
Public Shared Sub Main
Click3.Click()
Click3.Click()
Click3.Click()
End Sub
Private Shared Sub Click3_TplClick(ByVal Text As String) Handles Click3.TplClick
Console.WriteLine(Text)
End Sub
End Class Public Class TripleClicker
Public Event TplClick(ByVal Text As String)
Public Sub Click()
Static intCount As Integer = 0
intCount += 1
If intCount >= 3 Then
intCount = 0
RaiseEvent TplClick("The button was triple clicked.")
End If
End Sub
End Class</source>
The button was triple clicked.
