vb.net給控件加事件

兩種方法：

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1. 用WithEvents聲明變量，這樣你就可以像對(duì)待拖上去的控件一樣操作：

Public?Class?Form3

WithEvents?btn?As?New?Button

Private?Sub?Form3_Load(sender?As?Object,?e?As?EventArgs)?Handles?Me.Load

Controls.Add(btn)

End?Sub

Private?Sub?btn_Click(sender?As?Object,?e?As?EventArgs)?Handles?btn.Click

MsgBox(Now)

End?Sub

End?Class

2. 使用AddHandler 語句：

Public?Class?Form3

Private?Sub?Form3_Load(sender?As?Object,?e?As?EventArgs)?Handles?Me.Load

Dim?btn?As?New?Button

AddHandler?btn.Click,?AddressOf?btn_Click

Controls.Add(btn)

End?Sub

Private?Sub?btn_Click(sender?As?Object,?e?As?EventArgs)

MsgBox(Now)

End?Sub

End?Class

WithEvents (Visual Basic)：

AddHandler 語句：

vb.net如何寫在form1上右鍵被單擊的事件?

如果是窗體右鍵單擊事件，是

Private Sub Form1_MouseClick(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseClick

If e.Button = Windows.Forms.MouseButtons.Right Then

'這里寫你要的代碼

End If

End Sub

但是如果只是右鍵單擊就彈出菜單的話沒必要這樣，只需要在窗體上放置一個(gè)ContextMenuStrip控件，然后在Form的ContextMenuStrip屬性中綁定這個(gè)控件就可以了。

vb.net中如何用事件和委托，會(huì)C#中的事件和委托，但不知VB.net中的語法，望給個(gè)簡單的例子熟悉語法。

一委托：此示例演示如何將方法與委托關(guān)聯(lián)然后通過委托調(diào)用該方法。

創(chuàng)建委托和匹配過程

創(chuàng)建一個(gè)名為 MySubDelegate 的委托。

Delegate Sub MySubDelegate(ByVal x As Integer)

聲明一個(gè)類，該類包含與該委托具有相同簽名的方法。

Class class1

Sub Sub1(ByVal x As Integer)

MsgBox("The value of x is: " CStr(x))

End Sub

End Class

定義一個(gè)方法，該方法創(chuàng)建該委托的實(shí)例并通過調(diào)用內(nèi)置的 Invoke 方法調(diào)用與該委托關(guān)聯(lián)的方法。

Protected Sub DelegateTest()

Dim c1 As New class1

' Create an instance of the delegate.

Dim msd As MySubDelegate = AddressOf c1.Sub1

' Call the method.

msd.Invoke(10)

End Sub

二、事件

下面的示例程序闡釋如何在一個(gè)類中引發(fā)一個(gè)事件，然后在另一個(gè)類中處理該事件。AlarmClock 類定義公共事件 Alarm，并提供引發(fā)該事件的方法。AlarmEventArgs 類派生自 EventArgs，并定義 Alarm 事件特定的數(shù)據(jù)。WakeMeUp 類定義處理 Alarm 事件的 AlarmRang 方法。AlarmDriver 類一起使用類，將使用 WakeMeUp 的 AlarmRang 方法設(shè)置為處理 AlarmClock 的 Alarm 事件。

該示例程序使用事件和委托和引發(fā)事件中詳細(xì)說明的概念。

示例

' EventSample.vb.

'

Option Explicit

Option Strict

Imports System

Imports System.ComponentModel

Imports Microsoft.VisualBasic

Namespace EventSample

' Class that contains the data for

' the alarm event. Derives from System.EventArgs.

'

Public Class AlarmEventArgs

Inherits EventArgs

Private _snoozePressed As Boolean

Private nrings As Integer

'Constructor.

'

Public Sub New(snoozePressed As Boolean, nrings As Integer)

Me._snoozePressed = snoozePressed

Me.nrings = nrings

End Sub

' The NumRings property returns the number of rings

' that the alarm clock has sounded when the alarm event

' is generated.

'

Public ReadOnly Property NumRings() As Integer

Get

Return nrings

End Get

End Property

' The SnoozePressed property indicates whether the snooze

' button is pressed on the alarm when the alarm event is generated.

'

Public ReadOnly Property SnoozePressed() As Boolean

Get

Return _snoozePressed

End Get

End Property

' The AlarmText property that contains the wake-up message.

'

Public ReadOnly Property AlarmText() As String

Get

If _snoozePressed Then

Return "Wake Up!!! Snooze time is over."

Else

Return "Wake Up!"

End If

End Get

End Property

End Class

' Delegate declaration.

'

Public Delegate Sub AlarmEventHandler(sender As Object, _

e As AlarmEventArgs)

' The Alarm class that raises the alarm event.

'

Public Class AlarmClock

Private _snoozePressed As Boolean = False

Private nrings As Integer = 0

Private stopFlag As Boolean = False

' The Stop property indicates whether the

' alarm should be turned off.

'

Public Property [Stop]() As Boolean

Get

Return stopFlag

End Get

Set

stopFlag = value

End Set

End Property

' The SnoozePressed property indicates whether the snooze

' button is pressed on the alarm when the alarm event is generated.

'

Public Property SnoozePressed() As Boolean

Get

Return _snoozePressed

End Get

Set

_snoozePressed = value

End Set

End Property

' The event member that is of type AlarmEventHandler.

'

Public Event Alarm As AlarmEventHandler

' The protected OnAlarm method raises the event by invoking

' the delegates. The sender is always this, the current instance

' of the class.

'

Protected Overridable Sub OnAlarm(e As AlarmEventArgs)

RaiseEvent Alarm(Me, e)

End Sub

' This alarm clock does not have

' a user interface.

' To simulate the alarm mechanism it has a loop

' that raises the alarm event at every iteration

' with a time delay of 300 milliseconds,

' if snooze is not pressed. If snooze is pressed,

' the time delay is 1000 milliseconds.

'

Public Sub Start()

Do

nrings += 1

If stopFlag Then

Exit Do

Else

If _snoozePressed Then

System.Threading.Thread.Sleep(1000)

If (True) Then

Dim e As New AlarmEventArgs(_snoozePressed, nrings)

OnAlarm(e)

End If

Else

System.Threading.Thread.Sleep(300)

Dim e As New AlarmEventArgs(_snoozePressed, nrings)

OnAlarm(e)

End If

End If

Loop

End Sub

End Class

' The WakeMeUp class has a method AlarmRang that handles the

' alarm event.

'

Public Class WakeMeUp

Public Sub AlarmRang(sender As Object, e As AlarmEventArgs)

Console.WriteLine((e.AlarmText + ControlChars.Cr))

If Not e.SnoozePressed Then

If e.NumRings Mod 10 = 0 Then

Console.WriteLine(" Let alarm ring? Enter Y")

Console.WriteLine(" Press Snooze? Enter N")

Console.WriteLine(" Stop Alarm? Enter Q")

Dim input As String = Console.ReadLine()

If input.Equals("Y") Or input.Equals("y") Then

Return

Else

If input.Equals("N") Or input.Equals("n") Then

CType(sender, AlarmClock).SnoozePressed = True

Return

Else

CType(sender, AlarmClock).Stop = True

Return

End If

End If

End If

Else

Console.WriteLine(" Let alarm ring? Enter Y")

Console.WriteLine(" Stop Alarm? Enter Q")

Dim input As String = Console.ReadLine()

If input.Equals("Y") Or input.Equals("y") Then

Return

Else

CType(sender, AlarmClock).Stop = True

Return

End If

End If

End Sub

End Class

' The driver class that hooks up the event handling method of

' WakeMeUp to the alarm event of an Alarm object using a delegate.

' In a forms-based application, the driver class is the

' form.

'

Public Class AlarmDriver

Public Shared Sub Main()

' Instantiates the event receiver.

Dim w As New WakeMeUp()

' Instantiates the event source.

Dim clock As New AlarmClock()

' Wires the AlarmRang method to the Alarm event.

AddHandler clock.Alarm, AddressOf w.AlarmRang

clock.Start()

End Sub

End Class

End Namespace

vb.net中怎么寫窗體form關(guān)閉的事件?

this.close() 只是關(guān)掉，沒有釋放，不對(duì) me.close() 應(yīng)該釋放一下 me.Dispose() 給分吧。

一般來說都是this.close(); 方法調(diào)用一下就可以了。

這像是以前 VB 的寫法，VB.net 里不是這樣的，應(yīng)該是：

Private Sub Form_Closed(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Closed

MagBox("1111")

End Sub

注意，... Handles MyBase.Closed 是在同一行里的。

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