Why does File.Open() not open the file? - vb.net

Question

I am implementing a Save File button in my VB.NET Windows Forms application.
I am attempting to encapsulate the normally expected behaviour of Save buttons in Windows applications. I.E: If a file was already selected then open the current file it, write to it and save it; else if there is no current file, or Save As was used, then show a SaveFileDialog, then open, write and save just the same.
I currently have coded the function below but I keep getting an exception:
Cannot access a closed file
The file is created just fine, but is empty (It should contain "Test string"). I can't understand how the file is closed unless some kind of garbage collection is doing away with it somehow??
The current code:
Function SaveFile(ByVal Type As ProfileType, ByVal suggestedFileName As String, ByVal saveAs As Boolean, ByVal writeData As String) As Boolean
Dim FileStream As Stream = Nothing
Dim FolderPath As String = Nothing
Dim CancelSave As Boolean = False
Dim SaveFileDialog As SaveFileDialog = New SaveFileDialog()
Try
If Type = ProfileType.Product Then 'Select the initial directory path
FolderPath = ProductPath
Else
FolderPath = ProfilePath
End If
If (FileName = String.Empty Or saveAs = True) Then 'If a file is not already selected launch a dialog to allow the user to select one
With SaveFileDialog
.Title = "Save"
.AddExtension = True
.CheckPathExists = True
.CreatePrompt = False
.DefaultExt = "xml"
.Filter = "Xml Files (*.xml)|*.xml"
.FilterIndex = 0
.FileName = suggestedFileName
.InitialDirectory = FolderPath
If .ShowDialog(Me) = Windows.Forms.DialogResult.OK Then
FullyQualfiedPathName = New String(SaveFileDialog.FileName) 'Save the path and name of the file
FileName = Path.GetFileName(FullyQualfiedPathName)
Else
CancelSave = True
End If
.Dispose()
End With
End If
If (FileName <> String.Empty) Then 'Write the string to the file if the filewas correctly selected
FileStream = File.Open(FullyQualfiedPathName, FileMode.OpenOrCreate, FileAccess.ReadWrite) 'Open the file
Using FileStreamWriter As New StreamWriter(FileStream) 'Create the stream writer
FileStreamWriter.Write(writeData) 'Write the data
FileStream.Close() 'Clse the file
End Using
ElseIf (CancelSave <> True) Then 'Only throw an exception if the user *didn't* cancel the SavefileDialog
Throw New Exception("File stream was nothing", New IOException())
End If
Catch ex As Exception
MessageBox.Show(ex.Message & Environment.NewLine & FullyQualfiedPathName)
End Try
Return True
End Function

Answer 1

One problem I see is that you should be putting your File.Open in a Using block:
Using fs = File.Open(fullyQualfiedPathName, FileMode.OpenOrCreate, FileAccess.ReadWrite)
Using writer As New StreamWriter(fs) 'Create the stream writer
writer.Write(writeData) 'Write the data
'fs.Close() <--- you do not need this line becuase the "Using" block will take care of this for you.
End Using
End Using
I'm not sure if this will resolve your issue because I can't run your code, but the Using block will automatically take care of closing and cleaning up disposable instances like FileStream and StreamWriter, even if an exception is thrown.
By the way, you should use proper naming conventions (lower camel case) for local variables.