object reference not set to an instance of an object

Question

1.00/5 (2 votes)

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C#

protected void btndelete_Click1(object sender, EventArgs e)
    {
        int id1 = Convert.ToInt32(GridView1.SelectedDataKey.Value);
        StringCollection sc = new StringCollection();
        //string id = string.Empty;
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            CheckBox cb = (CheckBox)GridView1.Rows[i].Cells[0].FindControl("chkrow");
            if (cb != null)
            {
                if (cb.Checked)
                {
                    
                    //int id = Convert.ToInt32(GridView1.DataKeys[index].Values["ID"].ToString());
                   //int id1 = Convert.ToInt32(GridView1.SelectedDataKey.Value);
                    //id = GridView1.Rows[i].Cells[1].Text;
                    sc.Add(id);
                   
                }
            }
        }
        delete(sc);
         show();

Posted 29-Jul-13 19:31pm

Mohammed Shamsheer

Updated 29-Jul-13 19:45pm

Ankur^\m/

v2

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Comments

Sergey Alexandrovich Kryukov 30-Jul-13 1:36am

In what line?
—SA

_Asif_ 30-Jul-13 2:02am

why the code has comments? it is causing confusion. Please remove the comments by using improve question option

3 solutions

Solution 3

C#

//int id = Convert.ToInt32(GridView1.DataKeys[index].Values["ID"].ToString());
                   //int id1 = Convert.ToInt32(GridView1.SelectedDataKey.Value);
                    //id = GridView1.Rows[i].Cells[1].Text;
                    sc.Add(id);

In above code you have commented the line where you are initializing int variable 'id' and then using it again.
uncomment the line and Run again.

Posted 29-Jul-13 21:50pm

salah9

Solution 1

Make sure you have initialised all the objects that you have used to call any member function or data member.Often mistakenly data member or member functions are called using objects those have null value.Once initialised, it will be referenced to an instance of an object.Try to debug your code putting break points on suspected line.Then run the solution and debug it.Once you manage to initialise uninitialised object, error will be resolved.Hope this will help you...

Posted 29-Jul-13 19:38pm

Jitendra Sabat

Updated 29-Jul-13 19:59pm

v2

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Sergey Alexandrovich Kryukov · Accepted Answer · 2013-07-29T19:44:00

You did not show where the exception with the message "Object reference not set to an instance of an object" is thrown.

Not to worry. This is one of the very easiest cases to detect and fix. It simply means that some member/variable of some reference type is dereferenced by using and of its instance (non-static) members, which requires this member/variable to be non-null, but in fact it appears to be null. Simply execute it under debugger, it will stop the execution where the exception is thrown. Put a break point on that line, restart the application and come to this point again. Evaluate all references involved in next line and see which one is null while it needs to be not null. After you figure this out, fix the code: either make sure the member/variable is properly initialized to a non-null reference, or check it for null and, in case of null, do something else.

Please see also: want to display next record on button click. but got an error in if condition of next record function "object reference not set to an instance of an object"[^].

Sometimes, you cannot do it under debugger, by one or another reason. One really nasty case is when the problem is only manifested if software is built when debug information is not available. In this case, you have to use the harder way. First, you need to make sure that you never block propagation of exceptions by handling them silently (this is a crime of developers against themselves, yet very usual). The you need to catch absolutely all exceptions on the very top stack frame of each thread. You can do it if you handle the exceptions of the type System.Exception. In the handler, you need to log all the exception information, especially the System.Exception.StackTrace:
http://msdn.microsoft.com/en-us/library/system.exception.aspx[^],
http://msdn.microsoft.com/en-us/library/system.exception.stacktrace.aspx[^].

The stack trace is just a string showing the full path of exception propagation from the throw statement to the handler. By reading it, you can always find ends. For logging, it's the best (in most cases) to use the class System.Diagnostics.EventLog:
http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx[^].

Good luck,

—SA