I have about 50 radiobuttons on one form and I don't want to create an if statement for each one to detect when one changes, they are not part of a group box. How would I detect if any radiobutton changed and then write the name to another variable?
Put all the radio buttons on a panel and loop through the panels radio button controls, programmatically adding the same event handler for each as described by #Steve. One way I like to handle the event is to assign each radio button an index into its tag property. Then just store any relevant data in a list of objects and access the data for that radio button by pulling out it's corresponding object from the list using its tag. Much easier than doing it by hand.
Edit: Good catch #Neolisk. Updated answer.
You could Always set the CheckedChanged event for all 50 radiobuttons to the same event handler.
This is an example done via code:
Private Sub OnChange(sender As System.Object, e As System.EventArgs)
Dim rb = CType(sender, RadioButton)
Console.WriteLine(rb.Name + " " + rb.Checked.ToString)
End Sub
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
AddHandler Me.RadioButton1.CheckedChanged, AddressOf OnChange
AddHandler Me.RadioButton2.CheckedChanged, AddressOf OnChange
' and so on .....'
End Sub
I have done this via code and not using the designer to avoid the long add of Handles RadioButton1.CheckedChanged, RadioButton2.CheckedChanged .......
Related
Is there any way to catch all keydown event from any controls like textboxes inside a groupbox using one event handler.?
I try groupbox_keydown, but it's not triggered. I try to make some research in msdn and they say groupbox cannot get focus, so the keydown event will never raised. Is there any workaround for it.?
KeyPreview already set to True.
Edit:
i have some textboxes inside a groupbox. most of them have default or predefined value. what i want is when user have filled the required data and want to skip some textboxes, he just need to press some key like ctrl+enter to excecuting a click on a button in that groupbox or calling a procedure.
This seems to work ok It iterates through the controls collection in the groupbox and adds the .KeyDown event to the example handler.
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For Each ctl As Control In GroupBox1.Controls
AddHandler ctl.KeyDown, AddressOf GroupBox1Controls_KeyDown
Next
End Sub
Private Sub GroupBox1Controls_KeyDown(sender As Object, e As KeyEventArgs)
MessageBox.Show(DirectCast(sender, Control).Name)
End Sub
It may be that there are controls that don't have a .KeyDown event, so you might want to add an empty Try..Catch..End Try block into the code like this, but I wouldn't recommend it as it could hide other problems with the code.
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
For Each ctl As Control In GroupBox1.Controls
Try
AddHandler ctl.KeyDown, AddressOf GroupBox1Controls_KeyDown
Catch
End Try
Next
End Sub
I have an application where I have around 50 labels. In those labels a number is visible.
When the user clicks on the label the number needs to be written to an edit box.
This works fine, the only problem is that I have added 50 functions like below, and every time it’s the same. I was wondering if there is a common function for this
Remark: The labels have different names. So if its possible that this will work for all the labels on the form.
Private Sub LI_L_Click(sender As Object, e As EventArgs) Handles LI_L.Click
cmbOBJID.Text = LI_L.Text
End Sub
In the form designer, you should be able to set the handler for every label to the same function. Then you can use the "sender" parameter to determine which label is raising the event.
Notice also how all the controls that the function is linked to are listed after the "Handles" keyword. This is another way you could connect the code to all the labels if you prefer this over using the Visual Studio UI properties grid.
Private Sub LI_Click(sender As Object, e As EventArgs) Handles Label1.Click, Label2.Click, Label3.Click
cmdOBJID.Text = DirectCast(sender, Label).Text
End Sub
While it is easy to add several events to one handler in the style of
Private Sub LI_Click(sender As Object, e As EventArgs) Handles Label1.Click, Label2.Click, Label3.Click
It will be tedious for more than just a few labels.
You can add handlers programatically if you can find a way to refer to the labels you need to add handlers to. In this example, I put all the labels in a groupbox named "GroupBoxOptions":
Option Infer On
Option Strict On
Public Class Form1
Sub TransferDataToEditBox(sender As Object, e As EventArgs)
Dim lbl = DirectCast(sender, Label)
tbEditThis.Text = lbl.Text
End Sub
Sub InitLabelHandlers()
For Each lbl In GroupBoxOptions.Controls.OfType(Of Label)
AddHandler lbl.Click, AddressOf TransferDataToEditBox
Next
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
InitLabelHandlers()
End Sub
End Class
You may have some other way of selecting the labels which use the handler.
A pretty nice and quick solution is to traverse all the label controls on a form, assigning through the AddHandler function the event to run when a user clicks a label.
In code:
For Each c As Control In Me.Controls.OfType(Of Label)
AddHandler c.Click, AddressOf myLabelClick
Next
With the prevous snippet, we loop onto all the winform controls of type Label. A loop like that is useful when we have a lot of labels for which an event must be assigned. For each of them, we associate the event Click of the control with a customized Sub named myLabelClick. That subroutine will look like the following:
Private Sub myLabelClick(sender As Object, e As EventArgs)
cmdObjId.Text = DirectCast(sender, Label).Text
End Sub
Here we use the sender variable (which represents the control for which the click has been done) to access its Text property, and change the cmdObjId.Text accordingly.
Just to complement the solution from BlueMonkMN:
If you are using the DevExpress Tools, you need to import DevExpress.XtraEditors and change Label to LabelControl:
DirectCast(sender, LabelControl).Text
This worked for me.
In VB.net form, I have 20 buttons. They are named from btnLoc1 ~ btnLoc20. I do not want to code each button click event.
How to loop through each button to check which was clicked?
Do I need to implement timer tick to listen for button click event?
You can create a single event handler for all the Buttons. Select all the buttons in the designer, open the Properties window, click the Events button and then double-click the Click event. That will generate a Click event handler, just like when you double-click a Button in the designer, except this one will have multiple items in the Handles clause. You can then use the sender parameter to acces the Button that was clicked, e.g.
Private Sub Buttons_Click(sender As Object, e As EventArgs) Handles Button1.Click,
Button2.Click,
Button3.Click
Dim btn = DirectCast(sender, Button)
'Use btn here.
End Sub
The question then is, what do you want to do with that Button? If you want to do something different for each Button then you really should be creating separate event handlers. Alternatively, you might have a list of data and you want to use the item in that list that corresponds to the Button that was clicked. There are numerous ways to do that. One is to put the data in the Tag property of the Button itself and retrieve it from there. Another is to use concurrent indexes, e.g.
Dim buttons = Controls.OfType(Of Button)().ToArray()
Dim data = {"First", "Second", "Third"}
MessageBox.Show(data(buttons.IndexOf(btn)))
Obviously you need to ensure that the Button array and the data array do line up.
For being noticed if button was clicked - eventhandler is best choice.
But you can create only one eventhandler for all buttons
Private Sub Button_Click(sender As Object, e As EventArgs)
Dim button As Button = DirectCast(sender, Button)
MessageBox($"Button '{button.Name}' was clicked")
End Sub
Then in constructor
Public Sub New()
InitializeComponennts()
AddHandler Button1.Click, AddressOf Me.Button_Click
AddHandler Button2.Click, AddressOf Me.Button_Click
AddHandler Button3.Click, AddressOf Me.Button_Click
' and so on
End Sub
If you want to get information about how much each button was clicked, simply create dictionary and add click amount in one eventhandler
Private ButtonsClickAmount As New Dictionary(Of String, Integer)()
Private Sub Button_Click(sender As Object, e As EventArgs)
Dim button As Button = DirectCast(sender, Button)
If ButtonsClickAmount.ContainKey(button.Name) = True Then
ButtonsClickAmount(button.Name) += 1
Else
ButtonsClickAmount.Add(button.Name, 1)
End If
End Sub
I want to add the same event on my multiple textboxes. Let's say for example I want all my textboxes to trim the text value of itself when it has lost focus
my idea is to loop through all the textboxes and to add an event handler to all of it, but how will I refer to the textbox itself, I think it is the same as using the "this" keyword, but it is not available in vb.net - any other recommendations?
In order to get the element which triggered the event you can use the sender parameter of the event and cast it to the required type. It is not clear from the question which platform you are using, but below is the sample code for Windows Forms:
Private Sub txt1_TextChanged(sender As Object, e As EventArgs) Handles txt1.TextChanged
Dim currentTextbox as TextBox = CType(sender, TextBox)
' Do what you want with the textbox
End Sub
Similar principles should apply to Web forms or WPF as well.
Through all the textboxes Use handles for all textboxes
Private Sub TextBox1_LostFocus(sender As Object, e As EventArgs) _
Handles TextBox1.LostFocus, TextBox2.LostFocus
Dim txtBox As TextBox = sender
txtBox.Text = Strings.Trim(txtBox.Text)
End Sub
I've 100 buttons created dynamically in a form. How can I an add event handler to them?
You can use AddHandler to add a handler for any event.
For example, this might be:
AddHandler theButton.Click, AddressOf Me.theButton_Click
Just to round out Reed's answer, you can either get the Button objects from the Form or other container and add the handler, or you could create the Button objects programmatically.
If you get the Button objects from the Form or other container, then you can iterate over the Controls collection of the Form or other container control, such as Panel or FlowLayoutPanel and so on. You can then just add the click handler with
AddHandler ctrl.Click, AddressOf Me.Button_Click (variables as in the code below),
but I prefer to check the type of the Control and cast to a Button so as I'm not adding click handlers for any other controls in the container (such as Labels). Remember that you can add handlers for any event of the Button at this point using AddHandler.
Alternatively, you can create the Button objects programmatically, as in the second block of code below.
Then, of course, you have to write the handler method, as in the third code block below.
Here is an example using Form as the container, but you're probably better off using a Panel or some other container control.
Dim btn as Button = Nothing
For Each ctrl As Control in myForm.Controls
If TypeOf ctrl Is Button Then
btn = DirectCast(ctrl, Button)
AddHandler btn.Click, AddressOf Me.Button_Click ' From answer by Reed.
End If
Next
Alternatively creating the Buttons programmatically, this time adding to a Panel container.
Dim Panel1 As new Panel()
For i As Integer = 1 to 100
btn = New Button()
' Set Button properties or call a method to do so.
Panel1.Controls.Add(btn) ' Add Button to the container.
AddHandler btn.Click, AddressOf Me.Button_Click ' Again from the answer by Reed.
Next
Then your handler will look something like this
Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
' Handle your Button clicks here
End Sub
#Debasish Sahu, your answer is an answer to another question, namely: how to know which button (or any other control) was clicked when there is a common handler for a couple of controls? So I'm giving an answer to this question how I usually do it, almost the same as yours, but note that also works without type conversion when it handles the same type of Controls:
Private Sub btn_done_clicked(ByVal sender As System.Object, ByVal e As System.EventArgs)
Dim selectedBtn As Button = sender
MsgBox("you have clicked button " & selectedBtn.Name)
End Sub
I needed a common event handler in which I can show from which button it is called without using switch case... and done like this..
Private Sub btn_done_clicked(ByVal sender As System.Object, ByVal e As System.EventArgs)
MsgBox.Show("you have clicked button " & CType(CType(sender, _
System.Windows.Forms.Button).Tag, String))
End Sub
Some code for a variation on this problem. Using the above code got me my click events as needed, but I was then stuck trying to work out which button had been clicked.
My scenario is I have a dynamic amount of tab pages. On each tab page are (all dynamically created) 2 charts, 2 DGVs and a pair of radio buttons. Each control has a unique name relative to the tab, but there could be 20 radio buttons with the same name if I had 20 tab pages. The radio buttons switch between which of the 2 graphs and DGVs you get to see. Here is the code for when one of the radio buttons gets checked (There's a nearly identical block that swaps the charts and DGVs back):
Private Sub radioFit_Components_CheckedChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
If sender.name = "radioFit_Components" And sender.visible Then
If sender.checked Then
For Each ctrl As Control In TabControl1.SelectedTab.Controls
Select Case ctrl.Name
Case "embChartSSE_Components"
ctrl.BringToFront()
Case "embChartSSE_Fit_Curve"
ctrl.SendToBack()
Case "dgvFit_Components"
ctrl.BringToFront()
End Select
Next
End If
End If
End Sub
This code will fire for any of the tab pages and swap the charts and DGVs over on any of the tab pages. The sender.visible check is to stop the code firing when the form is being created.