Remove Checkboxes?

Remove Checkboxes?

• tomdart

  nicely observed Dave. :-)

  I would have pretty much said the same thing. But would have also asked if you wish to remove all checkboxes on the form if so then we pretty much can do this:

  for each currentControl as Control in Me.Controls

  if currentControl Is CheckBox then

  Me.Controls.Remove(currentControl)

  end if

  next

  
  
  

• Paul Baudouin

  ah I know why, you should be going through backwards from the collection...

  for counter as Integer = this.groupBox2.Controls.Count - 1 to 0 step -1

     if typeof(Me.Controls(counter)) Is CheckBox then

       Me.Controls.Remove(Me.Controls(counter))

    end if

  next

   

  
  
  

• beermix

  Thanks - I knew I had seen that before somewhere recently - glad you could remember where it was.

  For those who might be confused the following code works.

  For counter As Integer = Me.Controls.Count - 1 To 0 Step -1

  If TypeOf Me.Controls(counter) Is CheckBox Then

  Me.Controls.Remove(Me.Controls(counter))

  End If

  Next

  
  

• Roozbeh Sharafi

  Strange - when I run the following code it leaves five boxes behind. I wonder what you do that is different.

  Class Form1

  Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

  For X As Integer = 1 To 10

  Dim Box As New CheckBox

  Me.Controls.Add(Box)

  Box.SetBounds(200, 50 + 30 * X, 20, 20)

  Next

  End Sub

  Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

  For Each currentControl As Control In Me.Controls

  If TypeOf currentControl Is CheckBox Then

  Me.Controls.Remove(currentControl)

  End If

  Next

  End Sub

  End Class

  
  

• Robert Wakeland

  Using the controls collection is not a good way to remove controls as it will usually only remove half of them.

  I think what happens is that once you remove the first one the collection is updated and what was the second one now becomes the first one. But your loop thinks it has already done that one so it goes on to remove the next one, leaving the second one (which is now the first) in the collection. Does that make sense

  Something like the following seems to work ok

  Dim RemovedOne As Boolean

  Do

  RemovedOne = False

  For Each C As Control In Me.Controls

  If TypeOf C Is CheckBox Then

  Me.Controls.Remove(C)

  RemovedOne = True

  Exit For

  End If

  Next

  If Not RemovedOne Then

  Exit Do

  End If

  Loop While RemovedOne

  
  

• PerBylund

  actually I disagree with that dave. it WILL remove them if its been added into the collection.
  
  

• Olmann

  glad we sorted that out Dave! lol :-)
  
  

• Umair Khan

  Thanks Dave,
  That's worked, The code came from the following link, not sure if its worked or not <url>http://visualbasic.about.com/</url>
  It was an answer to a question that someone had asked and I started to play around with it and decided I would like the option to remove the Checkboxes.
  
  Here is the full code that I am using.
  
  Public Class Form1
  Dim CheckBoxSequence() As String
  Dim CheckSeq As Integer = 0
  Dim CheckBoxMatrix() As String
  Dim MatrixSize, i, RowCount, ColCount As Integer
  Dim RSize, CSize As Integer
  Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
  MakeBoxes()
  End Sub
  Private Sub SequenceCapture(ByVal sender As Object, ByVal e As System.EventArgs)
  CheckBoxSequence(CheckSeq) = sender.name
  CheckSeq += 1
  End Sub
  Private Sub Button1_Click( _
  ByVal sender As System.Object, _
  ByVal e As System.EventArgs)Handles Button1.Click
  
  For i As Int16 = 0 To CheckSeq
  Label1.Text = Label1.Text & CheckBoxSequence(i) & vbCrLf
  Next
  
  End Sub
  Private Sub MakeBoxes()
  RSize = CInt(RowSize.Text)
  CSize = CInt(ColSize.Text)
  MatrixSize = RSize * CSize
  ReDim CheckBoxMatrix(MatrixSize - 1)
  ReDim CheckBoxSequence(MatrixSize - 1)
  i = 0
  For RowCount = 1 To RSize
  For ColCount = 1 To CSize
  CheckBoxMatrix(i) = i.ToString
  Dim ChkBox As New CheckBox
  AddHandler ChkBox.CheckedChanged, _
  AddressOf SequenceCapture
  ChkBox.Name = "Checkbox" & i.ToString + 1
  ChkBox.Location = _
  New Point(20 * ColCount, 20 * RowCount)
  ChkBox.Text = ""
  ChkBox.Size = New Size(20, 20)
  Me.Controls.Add(ChkBox)
  i += 1
  Next
  Next
  
  End Sub
  Private Sub ColSize_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles ColSize.LostFocus
  MakeBoxes()
  End Sub
  Private Sub RowSize_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles RowSize.LostFocus
  MakeBoxes()
  End Sub
  Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
  Dim RemovedOne As Boolean
  Do
  RemovedOne = False
  
  For Each C As Control In Me.Controls
  
  If TypeOf C Is CheckBox Then
  Me.Controls.Remove(C)
  RemovedOne = True
  Exit For
  End If
  Next
  
  If Not RemovedOne Then
  Exit Do
  End If
  
  Loop While RemovedOne
  End Sub
  
  End Class
  
  
  
  
  
  

• Chris D Jones

  First of all there are a number of issues with the code you have posted for creating the checkboxes.

  1. If you call the procedure without entering anything into the textboxes then the lines that set RSize and CSize will generate exceptions.

  2. The CheckBoxMatrix seems a bit odd. The line that says

  CheckBoxMatrix(i) = i.ToString

  isn't really doing anything useful as it is simply setting the content of the array element to the string representation of the index.

  3. The line

  ChkBox.Name = "Checkbox" & i.ToString + 1

  generates an exception with Option Strict On (which is usually a good idea). Try changing it to

  ChkBox.Name = "Checkbox" & (i+1).ToString

  4. You haven't kept a reference to any of the checkboxes you have created which causes you a problem when you want to get rid of them.

  I would suggest you make CheckBoxMatrix an array of checkboxes, i.e.

  Dim CheckBoxMatrix() as CheckBox

  Then rework your loop as follows:

  For RowCount = 1 To Rsize
  For ColCount = 1 To Csize
  Dim ChkBox As New CheckBox
  AddHandler ChkBox.CheckedChanged, AddressOf SequenceCapture
  ChkBox.Name = "Checkbox" & (i + 1).ToString
  ChkBox.Location = New Point(20 * ColCount, 20 * RowCount)
  ChkBox.Text = ""
  ChkBox.Size = New Size(20, 20)
  CheckBoxMatrix(i) = ChkBox
  Me.Controls.Add(ChkBox)
  i += 1
  Next
  Next

  Then when you want to get rid of them all you have to do is

  Private Sub RemoveBoxes()
  For counter As Integer = 0 To Matrixsize - 1
  CheckBoxMatrix(counter).Dispose()
  Next
  End Sub
  

  
  
• Remove Checkboxes?