This is a very common requirement in applications and one that I always need to think a few extra minutes (hours, if you want) before I get it.
The GUI contains a CheckedListBox (or any other list) and the user want to be able to move the items up and down in the list. Yes I know - it seems trivial at first…
Here is one solution that uses a single method that is called with a parameter to indicate if the item is to be moved up or down.
'''
''' Moves an item in the listbox
'''
Private Sub MoveItemInListbox(ByVal up As Boolean)
' Check that something is selected
If checklistItems.SelectedItem Is Nothing Then
MessageBox.Show("Nothing selected")
Exit Sub
End If
' No flicker - on
' Remember the selected stuff, index, the item itself and if the item is
' checked or not
Dim selectedIndex As Integer = checklistItems.SelectedIndex
Dim selectedItem As Object = checklistItems.SelectedItem
Dim checked As Boolean = checklistItems.GetItemChecked(selectedIndex)
' Remove the item
' Calculate the new index
Dim newIndex As Integer = selectedIndex
If up Then
newIndex = newIndex - 1
Else
newIndex = newIndex + 1
End If
' Check that the index is within our bounds
If newIndex > checklistItems.Items.Count - 1 Or newIndex < 0 Then
Exit Sub
End If
' Put the item back in the list and check it if needed
checklistItems.Items.Insert(newIndex , selectedItem)
checklistItems.SetItemChecked(newIndex , checked)
' Set focus on the moved item
checklistItems.SelectedIndex = newIndex
checklistItems.EndUpdate()
end sub
Yeah - i’ve ripped the solution from http://www.msnewsgroups.net/group/microsoft.public.dotnet.languages.csharp/topic21474.aspx, if you don’t trust me.