Declare Anevent Handler
Jan 10, 2008
In an attempt to learn how to program in VB I thought I would have a go at working through some of the examples in the VB2008 express edition documentation. The following example expects an event handler to exist. I am having difficulty understanding how to declare an event handler.I have lifted the following from the VB2008 express edition documentation.[URL] CONTROLS AT RUN TIME... The Visual Basic 2008 example also assumes that an event handler named TextChangedHandler exists for the first TextBox control. - I NEED TO DO THIS. Private Sub TextBoxes_AddText(ByVal sender As System.Object, ByVal e As System.EventArgs)' Declare a new TextBox.Dim TextBoxB As New TextBox' Set the location below the first TextBoxTextBoxB.Left = TextBoxA.LeftTextBoxB.Top = TextBoxA.Top + 10' Add the TextBox to the form's Controls collection.Me.Controls.Add(TextBoxB)AddHandler TextBoxB.TextChanged, AddressOf TextChangedHandlerEnd SubSo I did something like this ...Private Sub TextChangedHandler(ByVal sender As System.Object, ByVal e As System.EventArgs) _Handles TextBoxA.TextChanged End
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Mar 29, 2010
I am teaching myself VB, and when I try to run this program, I am getting "An error occurred creating the form. See Exception.InnerException for details. The error is: Object reference not set to an instance of an object." If I was to declare the variables inside each event handler, the program runs, but why won't it run when I make the scope public? Seems repititous having to declare the variables in every event handler. [code]
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Aug 27, 2011
How do I get a Event Handler to fire from within a nother Event Handler?
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Apr 18, 2011
The event handlers in my parent class are never called though the events are raised in the child class.
The Code:
Public Class childForm
Public Event checkboxchangedEvent(ByVal checkbox1 As Boolean, ByVal checkbox2 As Boolean)
Private Sub checkboxchanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckBox1.CheckedChanged, CheckBox2.CheckedChanged
[code]....
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Mar 21, 2012
remove an event handler from within the event handler?
I have a class that gets data from a hand scanner. When the scan is complete and the data is validated, the class fires a custom "ScanComplete" event and returns the data in a custom EventArgs.
In the calling program, I'm creating an instance of the scanning class and adding a handler for the "ScanComplete" event. In the event handler I get the data that was scanned and then remove the handler.
It seems to be working but it feels wrong to remove the handler while I'm running inside the handler. Will this cause a problem?
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Oct 24, 2011
I don't understand why I only get 1 Message Box in the following case when I run using (CTRL-F5 - Run Without Debugger) in VS2010:
Public Class Form1
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
' Add the event handler for handling UI thread exceptions to the event.
AddHandler Application.ThreadException, AddressOf ThreadExceptionHandler
[code].....
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Jul 30, 2011
Is it possible to determine using VB.NET whether a certain event has any handlers attached to it? I don't own the event, in this particular case I want to know which of the items in a Windows.Forms.MenuStrip have their ToolstripMenuItem.Click event handled.
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Nov 20, 2009
Here is a problem with focus. I have a container(e.g. Panel) which contains some controls. How can I detect the focus event whenever any of the controls in the container has received or lost focus? Do I need to add handler for each control?
example: If all controls in the container have no focus, the container will report as inactive; if one of the controls has focus, the container will report as active.
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Sep 11, 2009
I designing download manager in vb.net. Which supports various file premium hosts[rs,hotfile].... My need is how to get the download handler of IE. When user navigate the link in IE the download link wil be catch by professional application like(dap, idm).... How to achieve in my application? I meant how to get redirected link?
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Nov 2, 2010
I ma using DevExpress controls (which doesnt matter for this example). I have a lookupEdit control and I never want the EditValue_Changed event to fire. Can I use RemoveHandler to do this? If so can someone give me a code example of doing this? Should I put RemoveHandler in the load event of the user control I am creating? Or does it go in the EditValue_Changed event of the lookupControl?
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Oct 28, 2009
When adding a handler I want to be sure adding a unique(single) instance of the delegate. [code]...
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Apr 26, 2010
How I can run handler from one application to another, for example: In application one i have form1 and button. In application two I have also form1 and button. Now how I can run handler for button on form1 in first application from applicaton two?
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Oct 23, 2011
I am trying to add a Handler, but it do not work. what am I missing? I getting this error.
Dim EditingTextBox As New TextBox
Dim Save_Button As New Button
Dim Cancel_Button As New Button
Private Sub Labels_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click
[code]....
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May 21, 2011
I have a label called "test" in my Index.asp page in my MVC view folder. I want to be able to change the value of it in my controller class.
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Feb 11, 2009
I have this H file in C, which includes[CODE]...
I get an error :FatalExecutionEngineError was detectedMessage: The runtime has encountered a fatal error. The address of the error was at 0x79e71bd7, on thread 0x11f0. The error code is 0xc0000005. This error may be a bug in the CLR or in the unsafe or non-verifiable portions of user code. Common sources of this bug include user marshaling errors for COM-interop or PInvoke, which may corrupt the stack.How do I translate it correctly ?
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Jan 26, 2012
In C# we do
byte[] imageData = new byte[];
SqlCom.Parameters.Add(new SqlParameter("@ImageData", (object)imageData));
which makes the imageData variable as an object.But How do i do this in Visual Basic??
Dim imageData As byte() = new Byte()
SqlCom.Parameters.Add(new SqlParameter("@ImageData", ?? ) <-----What Should i do here?
My code is like this
conn.Open()
Dim cmd As SqlCommand = New SqlCommand("SELECT PhotoID From Photo " & str8 & " And Photo = @Photo", conn)
cmd.Parameters.AddWithValue("@Photo", CType(Photo, Object))[code]....
It comes out error like this:The data types image and varbinary are incompatible in the equal to operator. What should I do?
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Mar 16, 2011
To declare an object in JS i can simply do the following:
var house = new Object();
house.window="square"
house.color="green"
In asp.net (VB) if i try doing the same
Dim house = new Object()
house.window="square"
i get an error: System.MissingMemberException: Public member 'window' on type 'Object' not found.
Do i have to create a house class before i can reference house.window? Is there no way to do it without creating a class?
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Dec 21, 2010
In my VB 6.0 code, I declare have the following line[code]...
However, in VB.NET, I get the error "expecting declaration". Isn't this a declaration statement? Is there a good reference for finding the differences between VB.NET and VB 6.0?
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Jun 20, 2009
In c++ we declare integer's hex value like this
int myint=0xabcd;
so how to i declare integer's hex value in vb.net
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Jan 24, 2011
I want to know if it is possible to declare a variable thrice.
[code]...
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Sep 23, 2008
i am making a program and the program runs too slow, so i would like to declare my functions at once.. not like this :
[Code]...
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Apr 30, 2012
How to declare a datasource?
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Oct 1, 2010
how to declare a textbox because my computer for a particular textbox say that "is not declared"
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Oct 27, 2009
i know it's probly really easy. but how do i declare App.EXEName
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Apr 24, 2012
I am trying to send mail that is formated as HTML but I get an error showing thatlFormatHtml is not declared. How do I declare it?
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Apr 17, 2011
I need to get the customer name from the user as in combo box when the user selects the user I want that selected customer name should be searched in the sql table (here table name is "obbalance") and all the entries in the table having the name as the selected customer naem it should be shown in the data grid view
cmd.Parameters.Add(New SqlParameter("@p1", SqlDbType.NVarChar).Value = ComboBox1.SelectedItem.ToString)
cmd = New SqlCommand("select obbalance from balance where custname=@p1", con)
dr = cmd.ExecuteReader()
Form2.Show()
After this also it shows a error. It shows error in declaration.
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May 9, 2012
I have created a new class, but I cannot use the textbox in the class as it is in the form1 class how would i declare it or use it in both classes?
i have tried form1.textbox1.text which workings in coding but when running my system it does nothing.
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Jul 15, 2010
Can anyone tell me how to declare updareresource api in vb.net . i searched pivoke site i didnt found example for vb.net and also show me an example please explaining its parameters
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Feb 6, 2012
trying to figure out how to declare items here. here is the
[Code]...
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Jun 13, 2011
What is the right way to declare an array
Dim lblname As Label() = New Label(get_num_of_children()) {}
Dim mealcheck As Integer() = New Integer(get_num_of_children()) {}
[code].....
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