Object reference not set to an instance of an object.

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Object reference not set to an instance of an object.
I have got error when i click on data in listbox. I just want to get the selected items from the listbox and fill it to my textbox.
How to solve the same
Here is my code

VB

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

Public Sub binddata()
    Dim str As String
    Dim con As SqlConnection = New SqlConnection("Data Source=ML0003135586;Initial Catalog=TestSQL;Integrated Security=True")
    con.Open()
    str = "Select distinct [title] from [tblForums]"
    Dim command As SqlCommand = New SqlCommand(str, con)
    ListBox1.DataSource = command.ExecuteReader
    ListBox1.DataTextField = "title"
    ListBox1.DataValueField = "title"
    ListBox1.DataBind()
    con.Close()
End Sub

Protected Sub ListBox1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ListBox1.SelectedIndexChanged
    txttitle.Text = ListBox1.SelectedItem.ToString
End Sub

Thanks in advance

Posted 26-Jul-11 15:19pm

drkterror

Updated 26-Jul-11 18:17pm

koolprasad2003

v3

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Comments

Sergey Alexandrovich Kryukov 26-Jul-11 22:26pm

Line of code where exception is thrown is not indicated.
--SA

shefeekcm 26-Jul-11 23:59pm

debug the code and provide the line the exception comes

Tajuddin_HYD 27-Jul-11 0:22am

the problem because of not using postback condition, actually his calling binddata() in page load

3 solutions

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Firo Atrum Ventus · Answer 1 · 2011-07-26T16:57:00

Solution 1

Typo at txttitle.Text?

Posted 26-Jul-11 16:57pm

Firo Atrum Ventus

Tajuddin_HYD · Answer 2 · 2011-07-26T17:31:00

Solution 2

HI,
use this in page load

VB

If Not IsPostBack Then
    binddata()
End If

Posted 26-Jul-11 17:31pm

Tajuddin_HYD

koolprasad2003 · Answer 3 · 2011-07-26T18:30:00

Why do you use Server side event to get selected item in Textbox.
Use Javascript it will help you to improve the performance.

Here is example

<head runat="server">
    <title>Untitled Page</title>
    <script language="javascript" type="text/javascript">
    function callME()
    {
        alert(document.getElementById("lst1").value);
    }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <asp:ListBox runat="server" ID="lst1" onclick="return callME()">
        <asp:ListItem Text="a" Value="a1"></asp:ListItem>
        <asp:ListItem Text="b" Value="b1"></asp:ListItem>
    </asp:ListBox>
    </form>
</body>

Hope it helps