Object reference not set to an instance of an object

Question

1.00/5 (1 vote)

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Hi all,

I got this exception: "object reference not set to an instance of an object".
Why did this exception occur?

Can you please suggest me?

C#

private void AssignmentCollector()
   {
       try
       {
           if (Request.QueryString["flag"] == "1")
           {
               EmployeeDataset = (DataSet)Session["DataSet"];
               if (EmployeeDataset != null)
               {
                   GvEmpDetails.DataSource = "";
                   GvEmpDetails.DataSource = EmployeeDataset;
                   GvEmpDetails.DataBind();
               }
               //Checking the Matching Investigators from Case assignment
               //ArrayList emp = new ArrayList();
               //emp = (ArrayList)Session["empId"];
               empName = (string)Session["employeName"];
               email = (string)Session["Employeemail"];
               string[] emplist = null;
               if (empName != null)
               {
                   emplist = empName.Split(',');
               }
               //Retrieve Rowid
               int rowid = 0;
               gridpagesize = GvEmpDetails.PageSize;
               sessionPageIndex = (int)Session["PageIndex"];
               startIndex = sessionPageIndex * gridpagesize;

              for (int i = 0; i < emplist.Length; i = i + 1)// at this line i am getting that exception.after coming here it is going to catch block
                 {
                   rowid = 0;
                   for (int j = startIndex; j < (startIndex + GvEmpDetails.Rows.Count); j++)
                   {
                       //string id = EmployeeDataset.Tables[0].Rows[j][0].ToString();
                       CheckBox empCheckBox = (CheckBox)GvEmpDetails.Rows[rowid].Cells[0].FindControl("EmployeeCheckBox");
                       Label employeename = (Label)GvEmpDetails.Rows[rowid].Cells[1].FindControl("lblFName");
                       if (emplist[i].ToString() == employeename.Text)
                       {
                           empCheckBox.Checked = true;
                           EmployeeDataset.Tables[0].Rows[j]["Checked"] = "Checked";
                           //empEmail+= emp[i+2].ToString() + ",";
                           if (empName.Contains(emplist[i].ToString()))
                           {
                           }
                           else
                           {
                               empName += emplist[i].ToString() + ",";
                               email += EmployeeDataset.Tables[0].Rows[j]["EmailId"].ToString() + ",";
                           }
                       }
                       rowid++;
                   }

               }
               Session["DataSet"] = EmployeeDataset;
               Session["employeName"] = empName;
               Session["Employeemail"] = email;
           }
           else if (Request.QueryString["flag"] == "2")
           {
               GrpDataset = (DataSet)Session["GrpdSet"];
               if (GrpDataset != null)
               {
                   gvGroupMailId.DataSource = "";
                   gvGroupMailId.DataSource = GrpDataset;
                   gvGroupMailId.DataBind();
               }
               empName = (string)Session["empGrpName"];
               string[] emplist = null;
               if (empName != null)
               {
                   emplist = empName.Split(',');

                   int rowid = 0;
                   gridpagesize = gvGroupMailId.PageSize;
                   sessionPageIndex = (int)Session["GPageIndex"];
                   startIndex = sessionPageIndex * gridpagesize;
                   for (int i = 0; i < emplist.Length; i = i + 1)
                   {
                       rowid = 0;
                       for (int j = startIndex; j < (startIndex + gvGroupMailId.Rows.Count); j++)
                       {
                           //string id = EmployeeDataset.Tables[0].Rows[j][0].ToString();
                           CheckBox empCheckBox = (CheckBox)gvGroupMailId.Rows[rowid].Cells[0].FindControl("EmployeeCheckBox");
                           Label employeename = (Label)gvGroupMailId.Rows[rowid].Cells[1].FindControl("lblGroupName");
                           if (emplist[i].ToString() == employeename.Text)
                           {
                               empCheckBox.Checked = true;
                               GrpDataset.Tables[0].Rows[j]["Checked"] = "Checked";
                               //empEmail+= emp[i+2].ToString() + ",";
                               if (empName.Contains(emplist[i].ToString()))
                               {
                               }
                               else
                               {
                                   empName += emplist[i].ToString() + ",";
                                   email += GrpDataset.Tables[0].Rows[j]["EmailId"].ToString() + ",";
                               }
                           }
                           rowid++;
                       }
                   }
                   Session["GrpdSet"] = GrpDataset;
                   Session["empGrpName"] = empName;
                   Session["employeeGrp"] = email;
               }
           }
       }

Hi all,

please check this code. In this I am getting the exception that I mentioned above.
Please suggest me.

Posted 8-Feb-11 0:12am

mandarapu

Updated 8-Feb-11 22:42pm

JF2015

v5

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Comments

Monjurul Habib 8-Feb-11 14:27pm

please provide a sample code.

mandarapu 9-Feb-11 2:48am

hi i provide the code and i mentioned where error is coming please check and suggest me

JF2015 9-Feb-11 4:43am

Edited to add code formatting.

3 solutions

Solution 2

You're trying to call a method or access a property of an object that is null.

eg

C#

MyObject myObject = null;
myObject.MyMethod(); // error thrown here

Run the code through the debugger and you'll see it.

Posted 8-Feb-11 1:48am

Chris Maunder773.4K

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Abhinav S · Accepted Answer · 2011-02-08T00:16:00

You will get this error when you try an access an object that has not been instatiated.

For e.g. I have a class Employee which has a Name attribute.

Employee obj;
MessageBox.Show(obj.Name.ToString()); //will throw this error as obj is still null

What you should be doing is instantiating your object using the new keyword.

CPallini · Accepted Answer · 2011-02-08T22:54:00

Solution 3

It looks like emplist.Length makes the exception happen.
You're strongly encouraged to use the debugger to step into your code (check, for instance, the runtime value of empName).
:)

Posted 8-Feb-11 22:54pm

CPallini