Mover Box

Colonel Angus · February 20th, 2004, 09:34 AM

I am working on what I have come to call a "Mover Box". That is, two listboxes with buttons between them to allow the user to move selections from one box to the other.

The process has 2 steps:
1. Taking the selection(s) made in one box and adding them to the other.
2. Removing them from the originating listbox.

Step 1 went smoothly with this code:

Code:

Dim li As ListItem
For Each li In lbOrigin.Items
    If li.Selected Then
        lbDestination.Items.Add(New ListItem(li.Text, li.Value))
    End If
Next

However, I thought that step 2 would be as straightforward with this code:

Code:

For Each li In lbOrigin.Items
    If li.Selected Then
        lbOrigin.Items.Remove(li)
    End If
Next

When I run this code, step 2 generates the error, "Collection was modified; enumeration operation may not execute."

I'm having trouble finding a way around this. I have tried a few avenues, but all were dead ends.

Any ideas on how I can remove these items successfully?

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In God we trust, everything else we test.

Colonel Angus · February 20th, 2004, 10:22 AM

Ok, file this under "I shouldn't have over complicated this" or under "Duh".

The solution is this. I was thinking that I was dealing with a collection, and that the SelectedItem property was only a single value - likely the first or last Item that I clicked on.

Well, I was only partly wrong. All I needed was this:

Code:

lbOrigin.Items.Remove(lbAvailable.SelectedItem)

That takes care of the error, but only the first item selected is removed.

-Colonel

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In God we trust, everything else we test.