Looping through controls

[hagadorn]

Hi im trying to loop through only the listviews in a group that i have on my form. Here is the code i am using at the moment:

'disable all but the processor group to allow the form to be filled in the correct order
        For Each grp As GroupBox In Me.Controls
            If grp.Name <> "grpProcessors" Then
                grp.Enabled = False
                For Each lst As ListView In grp.Controls
                    lst.Items.Clear()
                Next
                For Each txt As TextBox In grp.Controls
                    txt.Text = ""
                Next
            End If
        Next

The problem with this is that if a certain control in the grp.controls list is not a listview then the programme crashes. The same problem is present in looping through the groupboxes on the form however if there are no non-groupbox controls then the loop works. How would i loop through the list of controls and only find the listview boxes?

 

[JohnH]

"for each .. in controls" iterates ALL controls in the collection, and not all of them may be groupboxes etc.

for each c as control in x.controls
  if typeof c is groupbox then
    directcast(c, groupbox).enabled = true

  end if
next

 

[hagadorn]

thanks very much that works fantastically

 

[JohnH]

When you upgrade to VB 2008 you can do similar to what you first tried, for example by extension methods:

For Each b In Me.Controls.OfType(Of Button)()

Next

and LINQ:

For Each b As Button In From c In Me.Controls Where TypeOf c Is Button

Next