VB.NET CheckboxList doubles when button is clicked. Why? - asp.net

Question

Every time I click the Delete Button, the check marks double in quantity:
Public Class About
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim di As New IO.DirectoryInfo("C:\Images\")
Dim imageArray As IO.FileInfo() = di.GetFiles()
Dim image As IO.FileInfo
'clear imageArray
'list the names of all images in the specified directory
For Each image In imageArray
CheckBoxList1.Items.Add(image.Name)
Next
End Sub
Protected Sub btnDelete_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnDelete.Click
For count As Integer = 0 To CheckBoxList1.Items.Count - 1
If CheckBoxList1.Items(count).Selected Then
File.Delete("C:\Images\" & CheckBoxList1.Items(count).ToString)
End If
Next
End Sub
End Class
The checkboxlist isn't refreshed so that the checkbox that I deleted is removed from the checkboxlist. How do I accomplish that? Thanks!

Answer 1

On a button click, Page_Load is ran again, so the code that adds the checkboxes is ran a second time.
Add a check for Page.IsPostBack, and only add the checkboxes if it is not a postback.
If Not Page.IsPostBack Then
For Each image In imageArray
CheckBoxList1.Items.Add(image.Name)
Next
End If
(I hope syntax is right... Not used to VB)

Answer 2

the whole content of the Page_Load event handler has to be executed only once in your case, so rewrite it like this:
If Not IsPostBack Then
Dim di As New IO.DirectoryInfo("C:\Images\")
Dim imageArray As IO.FileInfo() = di.GetFiles()
Dim image As IO.FileInfo
'clear imageArray
'list the names of all images in the specified directory
For Each image In imageArray
CheckBoxList1.Items.Add(image.Name)
Next
End If