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POHow do I make a ListBox refresh its item text?
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copied!<p>I'm making an example for someone who hasn't yet realized that controls like <code>ListBox</code> don't have to contain strings; he had been storing formatted strings and jumping through complicated parsing hoops to get the data back out of the <code>ListBox</code> and I'd like to show him there's a better way.</p> <p>I noticed that if I have an object stored in the <code>ListBox</code> then update a value that affects <code>ToString</code>, the <code>ListBox</code> does not update itself. I've tried calling <code>Refresh</code> and <code>Update</code> on the control, but neither works. Here's the code of the example I'm using, it requires you to drag a listbox and a button onto the form:</p> <pre><code>Public Class Form1 Protected Overrides Sub OnLoad(ByVal e As System.EventArgs) MyBase.OnLoad(e) For i As Integer = 1 To 3 Dim tempInfo As New NumberInfo() tempInfo.Count = i tempInfo.Number = i * 100 ListBox1.Items.Add(tempInfo) Next End Sub Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click For Each objItem As Object In ListBox1.Items Dim info As NumberInfo = DirectCast(objItem, NumberInfo) info.Count += 1 Next End Sub End Class Public Class NumberInfo Public Count As Integer Public Number As Integer Public Overrides Function ToString() As String Return String.Format("{0}, {1}", Count, Number) End Function End Class</code></pre> <p>I thought that perhaps the problem was using fields and tried implementing <em>INotifyPropertyChanged</em>, but this had no effect. (The reason I'm using fields is because it's an example and I don't feel like adding a few dozen lines that have nothing to do with the topic I'm demonstrating.)</p> <p>Honestly I've never tried updating items in place like this before; in the past I've always been adding/removing items, not editing them. So I've never noticed that I don't know how to make this work.</p> <p>So what am I missing?</p>

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