I'm trying to complete this airline reservation application, but having a problem in this part of the question:Creat an event handler for the FlightBindingSource's PositionChanged event: select FlightBindingSource in the class Name combobox then select position changed in method name combobox to creat the FlightBindingSource's PositionChanged event handler. Write a code to access the currently displayed flight object and pass its flightNumber to method DisplayPassengers as a decimal.This Is my code so far:
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Public Class AirlineReservationForm Private database As New ReservationsDataClassesDataContext() Private Sub FillAll()[code].....
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
I'm making a very basic vb.net winforms app, essentially you can drag files into it, and it then uses a batch file to process the files.
It's pretty simple and everything is going to plan so far, it accepts the right files, it uses the batch file to process them and the batch file does what it is supposed to.The only problem is that I don't know how to hook into the Exited event that can/should be raised by the batch file process when the process completes...
I want the DOS window of the batch file to remain hidden while it is running, so I have used ProcessStartInfo to specify the batch file, then set the WindowStyle property of the process to ProcessWindowStyle.Minimised, then used System.Diagnostics.Process.Start(myBatch) to start the process at the appropriate moment.
This is fine, it works and does what I want. However, the only way to tell when a process ends is to use the Exited event. But the Exited event apparently only works with a Process not a ProcessStartInfo. I could switch to use Process instead but then I couldn't (AFAIK) run the DOS window minimised... I've only been writing .net for a few days. This is how I'm running the batch file:
Dim myBatch As New ProcessStartInfo("C:\batchFiles\test.bat") myBatch.WindowStyle = ProcessWindowStyle.Minimized system.Diagnostics.Process.Start(myBatch)
I am having an Activex Application (dll) which contains a third party control ie a Chart Control, as well as a Windows Application(.EXE). I am using that dll project in my exe application in order to populate the Activex user Control. If i double-click on the Activex Control, how can i pass an event handler from this dll Project to Windows application? If this event gets worked successfully, i have to load a screen from that windows application.
When the user clicks on the Activex Control, ie the Chart Control, is there any way to send a event handler from dll project to Windows Application?
The only way I know to force a paint event in my pictureboxes is to do a 'Picturebox1.invalidate'. I read that this isn't the best way to do it though, so what's the best way to make my picture boxes repaint?
I have a login form that when the user clicks OK and logs in successfully it loads the main application form.However when I show the main form and close the login form, the app is firing the shutdown event.Is this because the app thinks that the login form is the only form open and thus fires the shutdown event?Here is the code for the login routine, when I call Me.Close() at the end is when the shutdown event is fired. Am I doing things out of order? I used to do it this way in VB6 with no problems (I know they're a lot different).Note, it's nothing in frmMain either, this happens no matter what form I try to open.
Private Sub btnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOK.Click 'iLoginResult = 0 : Success ' 1 : Invalid user name or password ' 2 : Other login error
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?
When I utilize AddHandler in VB to add my own method to the Click event :
AddHandler Button.Click, AddressOf myButton_Click
I see that my code executes last - after other event handlers for the Button_Click event. Is there a way to insert my event handler in front of other events so that it executes first?
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.
sometimes, when I use Form.close() when debugging my program, although the form is closed, the application is still running. I noticed this behaviour when using the msgbox function.
I've been looking for a solution to this for several hours now and cannot find a solution.
The Scenario:I have a masterpage baseclass (called basemaster)All of my master pages inherit from basemaster basemaster defines an event 'Public Event HandleClickEvent As EventHandler'I have a masterpage named master1 master1 defines an event handler 'Public Shadows Event HandleClickEvent As EventHandler'master1 has a user control named usr1 usr1 has a button that raises event ButtonClicked when clicked I have a page (thePage) that uses master1 thePage has a button click event handler that it registers like so: 'AddHandler Master.HandleClickEvent, AddressOf HandleTheClick' master1 has code something like:
Protected Sub Usr1_ButtonClicked(ByVal sender As Object, ByVal e As System.EventArgs) Handles Usr1.ButtonClicked RaiseEvent HandleClickEvent(sender, e) End Sub when thePage loads I see it register the handler on master1 when the button is clicked, Usr1_ButtonClicked is fired and I step through the RaiseEvent but HandleClickEvent on thePage is never reached.
how to add one event handler name clearallboxes that handles the TextChanged event for both examples(Customer text box and Total text box ) This event handler should clear the values in the text boxes that display the results.
i have a page which dynanically create a link when it load, after i click on the link it should loop in the database fetch all the record and display another set of link , then when i click on these link it should give me all information about this particular record it like this one
Q: when the page loads, it creates the first link which is associated with an event handler, it fire the first event handler (Getname) but it not firing the second event handler (GetnameDetails)
Protected Sub Page_Init(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Init If ViewState.Item("nameload") IsNot Nothing Then If ViewState.Item("nameload").ToString = "True" Then
I have a form that is derived from a base class. When the form is created a behavior class is also generated that handles event management, bindings, etc...I create a form instance(FormFoo). When the associated behavior class is created it has a method in it with a signature of: grid_EventA(....) Handles grid.eventA
I want to handle EventA in FormFoo instead of the behavior class so I remove the handler that was generated in the behavior class and add a handler that points to a method in FormFoo. This all works just peachy. The event is properly handled in FormFoo only.
Next I instantiate a modal form(FormBar) via a button click in FormFoo. I then close FormBar. Now we have a problem.When eventA fires it is now handled from the Event handler in FormFoo AND in the behavior class associated with form foo(bad).Is the event handler in the behavior class(grid_EventA(....) Handles grid.eventA) getting resubscribed when the form gets focus again? I don't understand how that event is getting resubscribed.
I figured it out I removed the Handles grid.EventA from the method signature:
grid_EventA(....) Handles grid.eventA
Then I added the handler during initialization of the BehaviorClass using:
AddHandler grid.EventA, AddressOf grid_EventA
Once I did that the problem went away. It appears that when you use MethodName(..) Handles that the event bindings get reset when the control comes back into focus.
public event EventHandler Trigger; protected void OnTrigger(EventArgs e) {
[Code]....
Is there a way to do this in VB.NET? Test for null I mean?
MORE INFO
I forgot to mention. I have classes written in C# but I am writing my unit tests in VB.NET.
I am trying this in the unit test...
If myObject.Trigger IsNot Nothing Then ''#do something End If
This is causing a compile time error which says ... "Public Event Trigger is an Event and cannot be called directly. Use the RaiseEvent statement to raise an event."
At the beginning of a VB .NET function I remove an event handler and add it again at the end of the function because the function's code would trigger those events and I do not want them to trigger for the duration of the function. This usually works, but I have run into a few situations where the event still gets called even though I have already removed it. Sometimes removing it twice at the beginning of the function fixes it, but other times no matter how many times I remove it, it still fires.
Edit:The code is in a Form that has a virtual mode datagridview. I want to run some operations that will trigger the CellValueNeeded event for the datagridview without that event being fired (because it will interfere).
Public Sub DoEventRaisingStuff() RemoveHandler grid.CellValueNeeded, AddressOf grid_CellValueNeeded 'Do things that would trigger CellValueNeeded AddHandler grid.CellValueNeeded, AddressOf grid_CellValueNeeded End Sub
Removing the handler multiple times does not prevent the event from firing, so it doesn't seem to be added multiple times somewhere else by accident.Is there a way to find out what event handlers are active?
I'd like to know how to attach an event handler in VB,There is a C# sample code in this URL that I want to convert to VB (Figure 8)
http://msdn.microsoft.com/msdnmag/issues/06/01/speechinWindowsVista/default.aspx?loc=&fig=true#fig8 I have succesfully converted every lines to VB except those :
I have a chart Component that was rendering based on my menu selection(say Sales data, Purchase data), I have two different class to render this, In main form i have a chart control(which was referenced by my appropriate class), When I choose "sales" both sales and purchase chart rendering event handler called, how to solve this?
I downloaded and installed VS2010 yesterday, and converted the app to VB2010.
The app works correctly except for one problem. I have a label array which has two event handlers defined, one for a double click and one for mouse down.
A double click is ignored and the mouse down event is raised. It shows the left button was clicked once.
If I comment out the mouse down handler, the double click event is raised and it shows left button was clicked twice.
What i want to accomplish is allow a user to double click an array element on the screen which then saves the number associated with that element and then click somewhere else to copy the data or alternatively, drag and drop the element to the new location.
The drag operation on the source element always triggers a mouse down, but so does the first of the two clicks in a double click.
It seems that none of the other newer events are raised, eg GiveFeedbackEvent, QueryContinueDrag, DragOver, etc.
So, how do I trap a double click and a drag start without using the mousedown event for the dragstart?
