如何在列表框中删除重复项VB.net

Question

I am trying to remove duplicates in a ListBox which is populated by a query pull. I use this code to prevent adding duplicates in VB 6.0 but does not work when converted over to VB.net. Is there a substitute method to prevent or remove duplicates.

colSchema = dr("Col_Schema").ToString
If Not lstSchema.Items.ToString.Contains(colSchema) Then
     lstSchema.Items.Add(New ListItem(colSchema))
End If

Answer 1

This code

lstSchema.Items.ToString

is converting Items to a string. Items is most likely the type ListBox.ObjectCollection (if this is WinForms) or a similar collection type for other UI frameworks. Calling ToString on such classes will end up calling Object.ToString, which just returns the name of the class.

Instead, try

lstSchema.Items.Contains(colSchema)

If that does not work for some reason, please update your question explaining exactly what you were trying to solve by calling ToString.

Answer 2

try

colSchema = dr("Col_Schema").ToString
dim exists as boolean = false
for i as integer = 0 to lstSchema.items.count - 1
if lstSchema.items.item(i) = colSchema then
exists = true
end if
next
if exists = false then
lstSchema.Items.Add(New ListItem(colSchema))
end if