Randomize listbox

Extensions.vb

Imports System.Runtime.CompilerServices

Module Extensions

    <Extension>
    Iterator Function Randomize(Of T)(items As IEnumerable(Of T)) As IEnumerable(Of T)
        Dim indexes As List(Of Integer) = Enumerable.Range(0, items.Count).ToList
        Dim rand As New Random
        While indexes.Count > 0
            Dim tmp As Integer = rand.Next(0, indexes.Count)
            Yield items.ElementAt(indexes(tmp))
            indexes.RemoveAt(tmp)
        End While


    End Function
End Module

Form1.vb

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Dim items = Enumerable.Range(0, 20)

        ListBox1.Items.AddRange(items.Cast(Of Object)().ToArray)


    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim items = ListBox1.Items.Cast(Of Object).Select(Function(i) CInt(i)).Randomize.ToArray

        ListBox1.Items.Clear()

        ListBox1.Items.AddRange(items.Cast(Of Object)().ToArray)
    End Sub
End Class