CODEWITHSUNDEEP
vba
Artur Alvaro
Artur Alvaro

Reputation: 115

What's wrong with this iterating over a collection code?

I want to pass the items from ListBox1 to ListBox2, and delete them from LisBox1. It throws a null exception at "lb2.Items.Add(item)" but can't find out why. It works fine with just one item though

I tried doing a "for each item in lb1.items... lb2.items.add(item) + lb1.items.remove(item)" but it wouldn't work for you can't modify a list while iterating over it or an exception will be thrown. Also tried other different approaches but couldn't make it work

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    If lb1.Items.Count > 0 Then
        Dim itemsAPasar((lb1.Items.Count - 1)) As Object 
        For Each item In lb1.Items 
            itemsAPasar(UBound(itemsAPasar)) = item  
        Next
        For Each item In itemsAPasar
            lb2.Items.Add(item) 
        Next
        For Each item In itemsAPasar
            lb1.Items.Remove(item)
        Next
    End If
End Sub

Upvotes: 0

Views: 33

Answers (1)

Brandon
Brandon

Reputation: 14196

It looks like you could simplify your approach a bit...

Dim itemsToMove = lb1.Items.ToList()
For Each item in itemsToMove
    lb1.Items.Remove(item)
    lb2.Items.Add(item)
Next

Upvotes: 3

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