Null Pointer Exception,Object reference not set to an instance of an object

[swathi amireddy]

Currently im trying to migrate a project from .net 1.1 to 2.0.While running the application its giving an exception for the below code while doing the update operation:

protected void btnUpdate_Click(object sender, System.EventArgs e)
{
int ParamID=Convert.ToInt16(Session["ParamID"].ToString());(showing exception at this line)
....
....
}
private void grdParameters_ItemCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
Session["ParamID"]=e.Item.Cells[0].Text.ToString();
.....
.....
....
}

The exception that is raised is:
"Null pointer Exception unhandled by the usercode".Object reference not set to an instance of an object.

[r035198x]

Which line is reported for the error? You do understand what the exception means, right?

[kenobewan]

I suggest place the session string in a variable and write to check it exists. You want to think about adding some logic should the session variable be empty.

[swathi amireddy]

I suggest place the session string in a variable and write to check it exists. You want to think about adding some logic should the session variable be empty.

By debugging,we came to know that its getting the NULL value.Can u suggest some code that we need to add to solve the issue??

[r035198x]

Correcting it is as easy as putting a test (if test) for null before dereferencing (.dotting) the value that is null.

[Murugs]

int ParamID=0;//Initialize with default value
if (Session["ParamID"] != null)
{
ParamID=Convert.ToInt16(Session["ParamID"]);
}

hope this will helps you..

[swathi amireddy]

int ParamID=0;//Initialize with default value
if (Session["ParamID"] != null)
{
ParamID=Convert.ToInt16(Session["ParamID"]);
}

hope this will helps you..

Thank you....
its working....