Uso de diferentes clases para verificar los controles de formulario principal

I'm struggling to wrap my head around a concept and I've been at this for 4-5 hours now. So I'm hoping that someone can explain this to me.

I have multiple checkboxes inside a tabpage labeled "tabpage2" on the main form "QoE" and I have multiple classes that need to know the check states of those checkboxes.

I first went about this using:

dim f as new QoE

in each class, then calling the checkboxes like this:

f.chkTcpRTT.checked

but the result is always coming back "False" whether the box is checked or not, which I am assuming has to do with the fact that I am using the word "new".

My second thought was to use the property method

Public Shared Property getchecker(ByVal chk As CheckBox) As Boolean
    Get
        Return chk.Checked
    End Get
    Set(ByVal value As Boolean)
        chk.Checked = value
    End Set
End Property

But this still leaves me with having to pass an object from the other class which I cant figure out. so I tried this:

Public Shared Property getchecker(ByVal txt As string) As Boolean
    Get
        For Each ctrl as Control in TabPage2.Controls
            If ctrl.name = txt Then
                 Return ctrl.Checked
            End If
        Next
    End Get
    Set(ByVal value As Boolean)
        txt.Checked = value
    End Set
End Property

But now I am getting the error: "Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class."

The methods that I am using to call these features are all "public shared" so why am I getting this error and how can I get these checkstates? If its possible I would like to use some variation of the first code, so why is everything coming back false? is it because of the "new" flag? I would love to know a little background if its possible.

Gracias chicos

preguntado el 26 de noviembre de 13 a las 23:11

2 Respuestas

Suena como TabPage2 is an instance variable, yet you are trying to reference TabPage2 de un Shared método donde TabPage2 no existe

Necesitas quitar el Shared modificador en el getchecker método.

Response re comments.

Intente algo como esto:

Public Property getchecker(ByVal txt As string) As Boolean
    For Each ctrl as Control in Me.TabPage2.Controls
        If ctrl.name = txt Then
                Return ctrl.Checked
        End If
    Next
    Return False
End Property

To use this you would pass your reference of f to the other class and it would call it like so f.getchecker("foo").

respondido 27 nov., 13:05

Tabpage2 is a container that contains 6 checkboxes, its a tabpage from a TAB control object.... Also, without the shared, how would I call the property from another class ? ... Plus I would have to pass it a checkbox object, how do I reference a checkbox from another class in the first place? - Nefariis

You can set the access modifier of the checkboxes to public and then you can access them from your main window as well (through the instance variable tabpage2). - styxxy

They have been set to public this entire time, and so is the tab container. I still cant seem to access them in anyway - Nefariis

You would need to pass a reference to the form to allow access. At the end of the day you need to pass some reference around to do what you want. A shared method has no idea of any instances of the class without being passed a reference. - Enigmatividad

Can you post some code? and I thought dim f as new QoE was passing a reference? - Nefariis

In order to call controls from other classes you have to initiate the form and all the controls.

Public Class Form1
    Public Shared f as Form1

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
       f = Me
    End Sub

End Class

Then in other classes just refer to f normally like

Form1.f.Textbox1.Text = ""

or

Form1.f.CheckBox1.Checked = True

Disfrutar

For some additional reading:

http://www.vbforums.com/showthread.php?744677-RESOLVED-Struggling-with-trying-to-access-a-control-on-a-form-from-seperate-classes&p=4563273&highlight=#post4563273

Respondido el 24 de enero de 14 a las 00:01

Not a great solution. f is null in your example. What happens if you have two Form1s open? - LarsTech

Like I said in the last post - You really should give it a try first. I'm currently using this in two of my programs. - Nefariis

Not trolling, just saw you post the exact same answer, so I posted the exact same comment. :-) - LarsTech

Yeah sorry, i deleted that, and I also added some extra reading and some other options - Nefariis

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