How to check that Dynamically created checkbox checked or not?

Question

I've created some dynamic checkboxes in table header row.

If the checkbox is checked , table will have another row with a textbox.

Checkbox changed event is firing very well but when I'm trying to check whether the checkbox is checked or not , it's generating exception :

Object Reference not set to an instance of an object.

Here is my code :

Creating Dynamic controls here :

 TableRow thead = new TableRow();
 for (int i = 0; i < dt_fundtype.Rows.Count; i++)
 {
     TableCell td = new TableCell();
     CheckBox chk = new CheckBox();
     chk.ID = "fund_" + dt_fundtype.Rows[i]["fund_type_cd"];
     chk.Text = dt_fundtype.Rows[i]["fund_type"].ToString();
     chk.AutoPostBack = true;
     chk.CheckedChanged += new EventHandler(Chk_Fund_CheckedChange);
     td.Controls.Add(chk);
     thead.Cells.Add(td);
 }
 tbl_fundtype.Rows.Add(thead);

Checkbox checked changed event :

public void Chk_Fund_CheckedChange(object sender, EventArgs e)
{
     TableRow tr = new TableRow();
     for (int i=0;i<tbl_fundtype.Rows[0].Cells.Count;i++)
     {
         string DynamicChkID ="fund_"+ dt_fundtype.Rows[i]["fund_type_cd"].ToString();
         CheckBox chk = new CheckBox();
         chk = (CheckBox)tbl_fundtype.Rows[0].Cells[i].FindControl("DynamicChkID");
         if (chk.Checked == true)//Here is the Exception
         {
             TableCell td = new TableCell();
             td.Text = "Test";
             tr.Cells.Add(td);
         }
     }

     tbl_fundtype.Rows.Add(tr);
     hfTab.Value = "fund";
     collapsestate = "expand";
}

The event is firing very well , but when I check that the checkbox is checked or not there's an exception.

How can I resolve this problem ? Kindly Help me Please

Answer 1

This is the example I use which work for me.
I've simplified the binding logic and lookup logic etc, to illustrate

protected void Page_Load(object sender, EventArgs e)        
{
    AddStuff();
}

private void AddStuff()
{
    TableRow thead = new TableRow();
    for (int i = 0; i < 10; i++)
    {
        TableCell td = new TableCell();
        CheckBox chk = new CheckBox();
        chk.ID = "fund_" + i;
        chk.Text = i.ToString();
        chk.AutoPostBack = true;
        chk.CheckedChanged += new EventHandler(Chk_Fund_CheckedChange);
        td.Controls.Add(chk);
        thead.Cells.Add(td);
    }
    tbl_fundtype.Rows.Add(thead);
}

public void Chk_Fund_CheckedChange(object sender, EventArgs e)
{
    for (int i = 0; i < 10; i++)
    {
        var chk = tbl_fundtype.FindControl("fund_" + i) as CheckBox;
        if (chk.Checked)
        {
            //I am checked
        }
    }
}

And on my markup page I have:
<asp:Table ID="tbl_fundtype" runat="server" />

Answer 2

protected void Page_Load(object sender, EventArgs e)
{
    DataTable dt = Rowcreation();

    TableRow thead = new TableRow();
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        TableCell td = new TableCell();
        CheckBox chk = new CheckBox();
        chk.ID = "fund" + dt.Rows[i]["ID"];
        chk.Text = dt.Rows[i]["Name"].ToString();    

        chk.AutoPostBack = true;
        chk.CheckedChanged += new EventHandler(chk_fun_checkedchange);
        td.Controls.Add(chk);
        thead.Controls.Add(td);
    }
    pnl.Controls.Add(thead);   
}

public void chk_fun_checkedchange(object sender, EventArgs e)
{
    DataTable dt = Rowcreation();
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        CheckBox chkbx = (CheckBox ) pnl.Parent.Controls[0].FindControl("fund"+dt.Rows [i]["ID"]);
        if (chkbx.Checked == true)
        {
            lbl.Text = chkbx.Text;
        }
    }
}

private DataTable Rowcreation()
{
    DataTable dt = new DataTable();
    dt.Columns.Add("ID");
    dt.Columns.Add("Name");
    DataRow dr = dt.NewRow();
    dr["ID"] = "1";
    dr["Name"] = "Name1";
    dt.NewRow();
    dt.Rows.Add(dr);

    DataRow dr1 = dt.NewRow();
    dr1["ID"] = "2";
    dr1["Name"] = "Name2";
    dt.Rows.Add(dr1);

    dt.NewRow();
    DataRow dr2 = dt.NewRow();
    dr2["ID"] = "3";
    dr2["Name"] = "Name3";
    dt.Rows.Add(dr2);

    return dt;
}