VB2010 read a csv in datagrid, update in grid and save to same csv - vb.net

Question

Created a procedure in VB2010 to read a csv-file in datagridviewer, update cells in grid and save to same csvfile
Opening the csvfile in the datagridviewer works fine,
Updating in the datagridviewer works fine also
But when I save the datagrid to a csv-file with the same name, I get an error message "The process Can not access the file because it is used by an other process".
But if I save it to an other filename it is ok.
Then I tried to copy the new file with the new filename back to the original filename.
I received still the same error message that I cant copy because the file is still in use.
Does anybody now how to solve this.
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim fName As String = ""
OpenFileDialog1.InitialDirectory = "H:\Data\2014\Software\VB2010\"
OpenFileDialog1.Filter = "CSV files (*.csv)|*.CSV"
OpenFileDialog1.FilterIndex = 2
OpenFileDialog1.RestoreDirectory = True
If (OpenFileDialog1.ShowDialog() = Windows.Forms.DialogResult.OK) Then
fName = OpenFileDialog1.FileName
End If
Me.TextBox1.Text = fName
Dim TextLine As String = ""
Dim SplitLine() As String
DataGridView1.ColumnCount = 5
DataGridView1.Columns(0).Name = "Name"
DataGridView1.Columns(1).Name = "Gender"
DataGridView1.Columns(2).Name = "Age"
DataGridView1.Columns(3).Name = "Ranking"
DataGridView1.Columns(4).Name = "Date"
If System.IO.File.Exists(fName) = True Then
Dim objReader As New System.IO.StreamReader(fName)
Do While objReader.Peek() <> -1
TextLine = objReader.ReadLine()
SplitLine = Split(TextLine, ",")
Me.DataGridView1.Rows.Add(SplitLine)
Loop
Else
MsgBox("File Does Not Exist")
End If
End Sub
Private Sub SaveGridDataInFile(ByRef fName As String)
'method called by button2
Dim I As Integer = 0
Dim j As Integer = 0
Dim cellvalue$
Dim rowLine As String = ""
Try
Dim objWriter As New System.IO.StreamWriter(fName, True)
For j = 0 To (DataGridView1.Rows.Count - 2)
For I = 0 To (DataGridView1.Columns.Count - 1)
If Not TypeOf DataGridView1.CurrentRow.Cells.Item(I).Value Is DBNull Then
cellvalue = DataGridView1.Item(I, j).Value
Else
cellvalue = ""
End If
rowLine = rowLine + cellvalue + ","
Next
objWriter.WriteLine(rowLine)
rowLine = ""
Next
objWriter.Close()
objWriter = Nothing
MsgBox("Text written to file")
Catch e As Exception
MessageBox.Show("Error occured while writing to the file." + e.ToString())
Finally
FileClose(1)
End Try
Call copy_file()
End Sub
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
'çall method SaveGridDataInFile
SaveGridDataInFile(Me.TextBox1.Text)
' FileCopy("H:\Data\2014\Software\VB2010\datagr_ex2.csv", "H:\Data\2014\Software\VB2010\datagr_ex.csv")
End Sub
Sub copy_file()
Dim FileToDelete As String
FileToDelete = "H:\Data\2014\Software\VB2010\datagr_ex.csv"
If System.IO.File.Exists(FileToDelete) = True Then
System.IO.File.Delete(FileToDelete)
MsgBox("File Deleted")
End If
FileCopy("H:\Data\2014\Software\VB2010\datagr_ex2.csv", "H:\Data\2014\Software\VB2010\datagr_ex.csv")
End Sub

Answer 1

My guess is you need to close the StreamReader you use to load the file before you can reopen the file to save it. The StreamReader class implements IDisposable so you can use VB.Net's Using Statement to automatically close the file when you're finished reading, i.e.
If System.IO.File.Exists(fName) = True Then
Using objReader As New System.IO.StreamReader(fName)
Do While objReader.Peek() <> -1
TextLine = objReader.ReadLine()
SplitLine = Split(TextLine, ",")
Me.DataGridView1.Rows.Add(SplitLine)
Loop
End Using
Else
MsgBox("File Does Not Exist")
End If