[RESOLVED] [2005] Handle Groups?

I was just wondering if their was an easy way to create one handle for several controls.

For instance, I have 20 buttons and I want them all to do the same thing when clicked. Instead of having 20 handles for each button.click, is there a way to create one handle that can cover them all, such as a grouping or something?

You just put them all in the Handles clause of the event handler. You can do it manually or have the IDE do it for you. To do that you select all the controls in the designer, open the Properties window, click the Events button and then double-click the event of interest.

That is pretty easy.

If you have dropped the buttons on form at design time then use this code:

vb.net Code:

Private Sub Button_Click( _
    ByVal sender As System.Object, _
    ByVal e As System.EventArgs _
) Handles Button1.Click, Button2.Click, Button3.Click, Button4.Click
 
    ' do stufff
End Sub

And if you are creating controls at run-time then use below code:

vb.net Code:

AddHandler Button1.Click, AddressOf Button_Click
AddHandler Button2.Click, AddressOf Button_Click
AddHandler Button3.Click, AddressOf Button_Click
AddHandler Button4.Click, AddressOf Button_Click

Just to clarify, if you were to follow the instructions I provided then you'd end up with code much like what DS provided in his first code snippet. If you need to know whcih Button was actually clicked then you can get a reference to it from the 'sender' parameter.

Thanks, that didn't really solve the problem that I addressed but jmc your first suggestion will work for now.

I've used multiple events in the handles for a while, so I know how that works. What I want to know is if there is a way to create one variable or something for a group of buttons, and then I can use that variable.click in the handles section of a procedure and it will cover them all.

I don't want to have to type in "Handles button1.click button2.click button3.click...".

All the way to 20 or however many I use.

jmc your first suggestion may work in that I don't have to do as much typing if I simply select and then use the properties window to assign them all to an event automatically.

Thank you both for the suggestions though.

If you have a lot of buttons, make them into an array of buttons, then create the AddHandler (per Deepak's post) in a simple loop.

How can I make an array of buttons?

Dim MyButtons() As Button

or you can create the array by clustering your existing buttons;

Dim MyButtons(4) As Button = {MyButton1, MyButton2, ExitButto, SaveButton}

Controls can also be grouped into an array programmatically, so you do not need to type all of them in, this can be done by looping through Me.Controls, and adding any occurrences of a button control to an array.

Arrays such as this allow you to loop through controls, rather than consulting each control with individual statements.

Ok so once I put the names of the button in the array, I can just use:

Handles MyButtons.Click

To have the click event for every button in the array all in one handle? I'll try it out.

Also, is there a specific command for looping through arrays? I know what you mean by looping through me.controls using "for each ctrl as control in controls", but is there something for arrays like "for each variable as [slot] in array"?

ok, let's be more succinct here.

If you have an array of buttons called MyButtons, you can loop through using loops such as;

Code:

---

For Each B As Button In MyButtons
    B.Enabled = False
Next

---

So using a loop like that, you can assign the same event handler to every button and have one sub that will be called when any of those buttons is clicked. Within that sub, you can determine which button has been clicked by virtue of the "sender" property.

To loop through all controls, you will need to determine if a given control is the type you want. So the loop below will show the names of all buttons on "Me."

Code:

---

        For Each Con As Control In Me.Controls
            If Con.GetType.ToString = "System.Windows.Forms.Button" Then
                MessageBox.Show(Con.Name & " is a button")
            End If
        Next

---

You do need care in a loop such as this to check the component type. If you did not do that and tried to change a button property, but the current control was actually a CheckBox for example, you will get an exception thrown (if the CheckBox does not have that same property).

Quote:

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Originally Posted by Vectris

Ok so once I put the names of the button in the array, I can just use:

Handles MyButtons.Click

To have the click event for every button in the array all in one handle? I'll try it out.

Also, is there a specific command for looping through arrays? I know what you mean by looping through me.controls using "for each ctrl as control in controls", but is there something for arrays like "for each variable as [slot] in array"?

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No you have misunderstood. An array is an array. It has no Click event. If you want to handle the Click events of multiple Buttons then you have to handle the Click events of multiple Buttons, plain and simple. You either have to put them all in the Handles clause or else you have to call AddHandler for them all. What you're suggesting was possible in VB6 with control arrays but is not in VB.NET

Basically, this a waste of time. You're writing code to save yourself writing code but, as I've demonstrated, you don't have to write the code you're trying to avoid anyway. Just use the designer to create and/or attach your event handlers, which is exactly why VB.NET doesn't support control arrays in the first place.

Quote:

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Originally Posted by jmcilhinney

No you have misunderstood. An array is an array. It has no Click event.

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Well I know arrays don't have click events but I was wondering if adding click to the end of a special kind of array for controls or something would automatically read the contents and handle the click events for all the controls in the array.

Quote:

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Basically, this a waste of time.

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Well I don't see this as a waste of time, I see it as a way to save time, that's why I'm asking.

As for the rest of your post, is that just a "no" that it' can't be done? I'm not used to using the designer to make handles, I just go to the view code area and select the control and then the event. Then I add in handles as I need them. I was just looking for a way to add a bunch of handles quickly or cover a bunch of handles with just one.

Fact of the matter is, if you put a whole bunch of buttons on your form, then you're going to need a whole bunch of handlers. The benefit of tying all buttons to a single handler is that much less code needs to be written, making your program leaner and more efficient.

But whining about the correct solution because you may have to do a little typing is just childish and pointless. In the time it took you to post complaints, you could have finished adding the required code and done something useful.

I always think writing the code to do the loops is much more efficient in the long run. I have found myself adding 80 event handlers to buttons using the designer, and then having to delete about 20, and add another 30, etc...
Using a loop you don't need to make any adjustments to your code after adding or removing buttons later.

First, create a List(Of Button) to hold your buttons. In the Form_Load loop through all the controls on the form and add only the buttons to this List.
In addition, you add an event handler to each button.

vb.net Code:

Dim buttons As List(Of Button)
 
Private Sub Form1_Load(...) Handles Mybase.Load
   
   For Each ctrl As Control In Me.Controls
      If TypeOf ctrl Is Button Then
         Dim btn As Button = DirectCast(ctrl,Button)
         buttons.Add(btn)
         AddHandler buttons_Click, AddressOf btn.Click
      End If
   Next
 
End Sub
 
Private Sub buttons_Click(sender As Object, e As EventArgs)
   Dim btn As Button = DirectCast(sender, Button)
 
   btn.Text = "Hi, I'm a clicked button!"
End Sub

Whenever you might need to loop through all the buttons now you can loop through the List:

vb.net Code:

For Each btn As Button In buttons
   btn....
Next

You might be looking for something like this:

vb.net Code:

Dim buttons() As Button
Dim textBoxes() As TextBox
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    'initialize array of controls we want to use
    buttons = New Button() {Button2, Button3, Button4, Button5}
    textBoxes = New TextBox() {TextBox1, TextBox2, TextBox3, TextBox4, TextBox5}
 
    'Attach whatever events you want to. Ensure correct spelling :)
    AttachEvent("Click", AddressOf Button_Click, buttons)
    AttachEvent("TextChanged", AddressOf TextBox_TextChanged, textBoxes)
End Sub
 
Private Sub AttachEvent(ByVal eventName As String, ByVal eventHandler As EventHandler, ByVal ParamArray ctrls() As Control)
    Dim e As Reflection.EventInfo = ctrls(0).GetType.GetEvent(eventName)
    For Each ctrl In ctrls
        e.AddEventHandler(ctrl, eventHandler)
    Next
End Sub
 
Private Sub Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)
    'button click event code here
    MsgBox(sender.Name & " clicked")
End Sub
 
Private Sub TextBox_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs)
    'text-change event code here
    MsgBox(sender.Name & " text-changed")
End Sub

The code is self-explanatory. Let me know if you need some clarifications.

Pradeep :)

Quote:

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Originally Posted by Vectris

Well I know arrays don't have click events but I was wondering if adding click to the end of a special kind of array for controls or something would automatically read the contents and handle the click events for all the controls in the array.

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There is no special kind of array. There was in VB6. There isn't in VB.NET.

Quote:

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Originally Posted by Vectris

Well I don't see this as a waste of time, I see it as a way to save time, that's why I'm asking.

As for the rest of your post, is that just a "no" that it' can't be done? I'm not used to using the designer to make handles, I just go to the view code area and select the control and then the event. Then I add in handles as I need them. I was just looking for a way to add a bunch of handles quickly or cover a bunch of handles with just one.

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All this talk of writing code to loop through all the buttons top attach event handlers is a waste of time. You asked for a quick way to add a control to a Handles clause and you have one: use the Properties window of the designer.

Quote:

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Originally Posted by MaximilianMayrhofer

But whining about the correct solution because you may have to do a little typing is just childish and pointless.

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I'm not whining, I asked a question and I want my question answered, that's why I asked it. I don't want a bunch of "no you can't do this", just don't answer it then. Also I fail to see any "correct solutions" other than using the properties window, and I'm not complaining about that at all, in fact that's what I'm going to use, and it doesn't involve typing.

@Nick

While the properties window should be faster that will work very well for adding handles during runtime or just as an alternate way. I also like having a list of buttons, I never thought of doing that but it can be useful, thanks.

Quote:

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All this talk of writing code to loop through all the buttons top attach event handlers is a waste of time.

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It's not a waste of time if I need to re-asign lots of handles during runtime . But properties window will most likely be what I use for now.