Problem in accesing mdi form

  • Thread starter Thread starter Pk
  • Start date Start date
P

Pk

Hi,

Im having a problem in forms. I have a mdi parent form named Main, and
a child form named form1.
From Main form, i have a certain menu item that when clicked, it opens
Click to expand...
form1. But the problem is that when I close form1 and I open it again
by accessing the menu, nothing happens.

When I tried to debug it, I put a breakpoint at the menu item

Private sub mnu1_click(byval sender as object, byval e system.args)
handles mnu1_click

dim frmadd as new form1
frmadd.mdiparent=me
frmadd.show()

End Sub

It generates an error, stating:

An unhandled exception of type 'System.ObjectDisposedException'
occurred in system.windows.forms.dll

Additional information: Cannot access a disposed object named "Form1".

This isnt a problem in VB6..

Thanks
 
PK,

In what form have you set this code.

Did you know that there are more experts for VB6 upgrading in the newsgroup

microsoft.public.dotnet.languages.vb.upgrading

Although this is a general question in the VB net language.
The most active newsgroup for that is

microsoft.public.dotnet.languages.vb

I hope this helps,

Cor
 
This is working for me just fine, the only way I can imagine this occuring
for you is that frmAdd is declared at a higher scope than you are showing
here.

However, may I make a suggestion?


When you dimension a variable, you should type it first.

dim frmAdd as form1 = new form1

or, preferred

dim frmAdd as form1
frmAdd = new form1

I use a hashtable to manage special child forms. That way I know if the
form is already open and I simple BringToFront(). I handle the form's
Closed() event from my mdi parent and remove the form from from my
hashtable, remove the event handler, and manually Dispose() it

private sub muOpenSpecial_Click(Sender, e)

dim frmAdd as form1

if not myForms.Contains("FormAdd') then

frmAdd = new form1
frmAdd.mdiParent = me
addhandler frmAdd.Closed, Addressof AddForm_Closed
myForms.add("FormAdd",frmAdd)
frmAdd.show

else

frmAdd = ctype(myForms("FormAdd"),from1)
if frmadd.windowstate = minimized then
if not me.ActiveMdiChild is nothing then
frmadd.windowstate=me.ActiveMdiChild
else
frmadd.windowstate=maximized
end if
end if

end if

end sub

private sub AddForm_Closed(Sender, e)
dim frmAdd as form1
frmAdd = ctype(sender,form1)
myForms.Remove("FormAdd")
removehandler frmAdd.Closed, Addressof AddForm_Closed
frmAdd.dispose
end sub
 
Hi,

thanks for code
but one thing i did not get i.e myForms
and where this should be written in mdi form or child form.

Looking for quick response.
Bye
 
myForms is the hashtable and all that code was intended to be placed in the
mdi parent.
 
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