Question

I’m having problems with finding my controls in my dynamically created literal control. I want to be able to grab the value in the label with the fnameID(x) id.

ASPX:

<div>   <asp:Panel ID='Panel1' runat='server'>   </asp:Panel> </div> <asp:Button ID='Button1' runat='server' Text='Button'      onclick='Button1_Click' /> 

CODE BEHIND:

protected void Page_Load(object sender, EventArgs e) {     for (int i = 0; i < 50; i++)     {         CheckBox _checkbox = new CheckBox();         _checkbox.ID = 'dynamicCheckListBox' + Convert.ToString(i);         Panel1.Controls.Add(_checkbox);         Panel1.Controls.Add(new LiteralControl('<Label id='fnameID'              + i + '' >test' + i + '</Label><br/>'));     }  }  protected void Button1_Click(object sender, EventArgs e) {     Label lbl = (Label)Panel1.FindControl('fnameID0');     Response.Write(lbl.Text); } 

Currently I am getting the following error when I click on the button:

Object reference not set to an instance of an object.  Exception Details: System.NullReferenceException: Object reference not set to an instance of an object. 

Source Error:

{ Label lbl = (Label)Page.FindControl('fnameID0'); **Response.Write(lbl.Text);** } 

Answer 1

Try explicitly setting the ID of the control you generate:

protected void Page_Load(object sender, EventArgs e) {     for (int i = 0; i < 50; i++)     {         CheckBox _checkbox = new CheckBox();         _checkbox.ID = 'dynamicCheckListBox' + Convert.ToString(i);         Panel1.Controls.Add(_checkbox);          LiteralControl dynLabel = new LiteralControl('<Label id='fnameID'              + i + '' >test' + i + '</Label><br/>');         dynLabel.ID = 'fnameID' + i.ToString();          Panel1.Controls.Add(dynLabel);     }  } 

You’re getting the null reference exception because no control with the specified ID is being found, so FindControl is returning null, and you can’t get the Text property of a null.