Export To TEXT FILES : ERROR :Object reference not set to an instance of an object

Question

1.00/5 (2 votes)

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I was trying to run this code:

VB

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

       If dataGridView1.RowCount > 0 Then

           Dim RowcCount As [String] = ""
           Dim Startuppath As String = Application.StartupPath + "/"
           'File Extension as your requirement .dat or .txt
           Dim Destinationpath As String = Startuppath & "" & DateTime.Now.ToString("dd-MMM-yyy") & ".txt"
           Using Streamwrite As StreamWriter = File.CreateText(Destinationpath)

               For i As Integer = 0 To dataGridView1.Rows.Count - 1
                   RowcCount = ""
                   For j As Integer = 0 To dataGridView1.Columns.Count - 1
                       If RowcCount.Length > 0 Then
                           RowcCount = RowcCount & "," & DataGridView1.Rows(i).Cells(j).Value.ToString()
                       Else
                           RowcCount = dataGridView1.Rows(i).Cells(j).Value.ToString()
                       End If
                   Next
                   Streamwrite.WriteLine(RowcCount)
               Next
               Streamwrite.WriteLine(Streamwrite.NewLine)
               Streamwrite.Close()
               MessageBox.Show("File Created Successfully")

           End Using

       Else
       End If
   End Sub

There is an error this line when the program is being exceuted.

RowcCount = dataGridView1.Rows(i).Cells(j).Value.ToString()

There error is

NullReferenceException was unhandled.
An unhandled exception of type 'System.NullReferenceException' occurred in AllTrialApplication.exe
Addition information: object reference not set to an instance of an object

Posted 7-Sep-14 22:55pm

NekoNao

Updated 8-Sep-14 14:41pm

v2

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4 solutions

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Abhinav S · Answer 1 · 2014-09-07T23:12:00

Solution 1

dataGridView1.Rows(i).Cells(j).Value.ToString() will throw an error if you are trying to typecast a null.
Thus check if dataGridView1.Rows(i).Cells(j).Value is null before typecasting to string.
Or elae, use Convert.ToString();[^].

Posted 7-Sep-14 23:12pm

Abhinav S

Abhinav S · Answer 2 · 2014-09-07T23:13:00

Solution 2

dataGridView1.Rows(i).Cells(j).Value.ToString() will throw an error if you are trying to typecast a null.
Thus check if dataGridView1.Rows(i).Cells(j).Value is null before typecasting to string.
Or elae, use Convert.ToString()[^].

Posted 7-Sep-14 23:13pm

Abhinav S

Comments

NekoNao 8-Sep-14 5:32am

There is data in the last row but still gets the error.

NekoNao 8-Sep-14 20:44pm

It always has errors in the LAST ROW. that it said it is NULL but there is data

MuhammadUSman1 · Answer 3 · 2014-09-08T17:42:00

The only solution which can help you is that you put break point and debug code line by line.
And trace what the exactly value you are showing in datagirdview and what you are trying to get.
and for helping check following links.

Debugging Your Visual Basic Application

if any issue the let me know.

-> M.U

NekoNao · Answer 4 · 2014-09-08T17:47:00

Solution 4

The only solution I got is that i changed

For i As Integer = 0 To dataGridView1.Rows.Count - 1

to

For i As Integer = 0 To dataGridView1.Rows.Count - 2

I do not know why but it works!

Posted 8-Sep-14 17:47pm