AJAX Generate Random Names from Array in VB

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AJAX Generate Random Names from Array in VB

ASP.NET AJAX Tutorial

This tutorial will show how we can use AJAX to dynamically generate a list of random names without calling postback. VB version.

This tutorial was created with Microsoft's ASP.NET AJAX Extensions, which can be downloaded at this link

This tutorial makes use of the UpdatePanel control in Visual Studio's AJAX toolbox. It will show you how we can generate random names from a string array at the click of a button, without postback.

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The first thing we need to do is start an ASP.NET AJAX-Enabled Web Site within Visual Studio .NET
Then we can add our UpdatePanel, button and label to the ASPX page:

<asp:ScriptManager ID="ScriptManager1" runat="server" />
<div>

<asp:UpdatePanel ID="UpdatePanel1" runat="server">

<ContentTemplate><fieldset><legend>Panel with Random Names</legend><br />

<asp:Button ID="Button1" runat="server" Text="Generate Random Names" OnClick="Button1_Click" />
<br />

<asp:UpdateProgress ID="UpdateProgress1" runat="server" DisplayAfter="100" DynamicLayout="true">

</asp:UpdateProgress>

<asp:Label ID="lblNames" runat="server"></asp:Label>

</fieldset></ContentTemplate>

</asp:UpdatePanel>

</div>

</form>

We add the following assembly reference, because we are goingto use a string array to store names:

Imports System.Collections.Generic

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Then we create the string array:

Private ReadOnly strNames() As String = {"Mark", "Tom", "Harry", "Sally", "Sandra", "Paul", "Anastasia", "David", "Alex", "Michael", "Tina", "Zachary", "Bob", "Elise"}

Then we create the method that will choose a list of names at random:

Private Sub FillListBoxRandom()

lblNames.Text = ""

Dim names As List(Of String) = New List(Of String)()

Dim count As Integer = strNames.Length

For i As Integer = 1 To 3

System.Threading.Thread.Sleep(100)
Dim rnd As New Random()
Dim number As Integer = rnd.Next(count)
Dim selName As String = strNames(number)
If (Not names.Contains(selName)) Then

names.Add(selName)

End If

Next i

For Each name As String In names

lblNames.Text += name & "<BR />"

Next name

End Sub

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The code-behind will look something like this:

Imports System.Collections.Generic

Partial Class _Default

Inherits System.Web.UI.Page

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)

FillListBoxRandom()

End Sub

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

End Sub

Private Sub FillListBoxRandom()