Q: TListBox.ItemIndex changes to -1 when accessing .Items

jimbu...@technologydynamics.com (Jim Burns)

Delphi Developer

Mon, 26 Apr 1999 03:00:00 GMT

Q: TListBox.ItemIndex changes to -1 when accessing .Items

I don't understand this one. Can anyone help?

Quite simply I have a master list and need to update my listbox with the
change. The code:

LayoutLB.Items[CurrentLayoutIndex] := LayoutList[CurrentLayoutIndex];

Once this line executes the ListBox, LayoutLB.ItemIndex changes to (-1).
It was valid before this line. I know I could update the entire list, but
I don't know if that will work, I'm gonna try it now, but I also really
don't want to update needlessly. Only 1 line needs changing at a time. ;)

Why?

Any ideas?

Many thanks in advance,

-- Jim Burns
Consultant Technology Dynamics
Pearland, Texas
(713) 485-0410
jimbu...@technologydynamics.com

Boris Ingr

Delphi Developer

Tue, 27 Apr 1999 03:00:00 GMT

Re:Q: TListBox.ItemIndex changes to -1 when accessing .Items

Quote

In article <55tbdd$...@ganja.nol.net> jimbu...@technologydynamics.com (Jim Burns) writes:
>From: jimbu...@technologydynamics.com (Jim Burns)
>Subject: Q: TListBox.ItemIndex changes to -1 when accessing .Items
>Date: Thu, 07 Nov 1996 18:56:59 GMT
>I don't understand this one. Can anyone help?
>Quite simply I have a master list and need to update my listbox with the
>change. The code:
> LayoutLB.Items[CurrentLayoutIndex] := LayoutList[CurrentLayoutIndex];
>Once this line executes the ListBox, LayoutLB.ItemIndex changes to (-1).
>It was valid before this line. I know I could update the entire list, but
>I don't know if that will work, I'm gonna try it now, but I also really
>don't want to update needlessly. Only 1 line needs changing at a time. ;)
>Why?
>Any ideas?

adding new items seems to invalidate the itemindex - perhaps you could stash
itemindex in a var prior to adding items, then set it back from the var
afterwards

HTH

Boris Ingram, Cyborg Software
boris...@iafrica.com
100076.3...@compuserve.com
http://www.pcb.co.za/users/borising/cyborg.htm

Other Threads

1. TListBox itemIndex changing

2. Access Violation in TListbox->Items->Strings when the Item is a verylong string

3. Access Violation in TListbox->Items->Strings when the Item is a very long string

4. TlistBox - Changing items attributes

5. Change the font of one item in TListBox?

6. How to handle item changed event with TListBox/TCheckListBox

7. Changing Item color in a TListBox

8. Moving TListBox items to another TListBox

9. TListBox - How do I Deselect all Selected Items in a TListBox

10. tlistbox.itemindex problem