Question

Hello I’m getting this error, while trying to save serial number to XML File.
If the file doesn’t exist, it saves the file fine, but if i change Registered tag to False in Xml file, and try again, it says “The Process Cannot acces the file … because it is being used by another process”.
In my main form i read the information from XML, and in my regform (which i open if registered tag in xml is false) i write to the file. is it because of that?! I don’t think so.
Here is my Registration class:

    Imports System.IO
    Imports System.Xml

    Public Class RegistrationClass
    Public Property SerialNumber As String
    Public Property Registered As Boolean = False
    Public Sub Write_Reg(ByVal FileString As String, ByVal RegisterName As String, ByVal          RegisterCompany As String, ByVal RegisterSerialNumber As String)
        Dim Registered As Boolean = False
        Dim Comment As String = "StroySoft 2012 Register Database"
        Dim SerialNumber As String = "dev-xxx-123"
        Dim ClientOS As String = Trim(My.Computer.Info.OSFullName)
        If RegisterSerialNumber = SerialNumber Then
            Dim settings As New XmlWriterSettings()
            settings.Indent = True

            ' Initialize the XmlWriter.
            Dim XmlWrt As XmlWriter = XmlWriter.Create(FileString, settings)

            With XmlWrt

                ' Write the Xml declaration.
                .WriteStartDocument()

                ' Write a comment.
                .WriteComment(Comment)

                ' Write the root element.
                .WriteStartElement("Data")

                ' Start our first person.
                .WriteStartElement("Register")

                ' The person nodes.

                .WriteStartElement("Name")
                .WriteString(RegisterName.ToString())
                .WriteEndElement()

                .WriteStartElement("Company")
                .WriteString(RegisterCompany.ToString())
                .WriteEndElement()

                .WriteStartElement("SerialNumber")
                .WriteString(RegisterSerialNumber.ToString())
                .WriteEndElement()

                Registered = True
                .WriteStartElement("Registered")
                .WriteString(Registered)
                .WriteEndElement()

                .WriteStartElement("ClientOS")
                .WriteString(ClientOS)
                .WriteEndElement()

                ' The end of this person.
                .WriteEndElement()

                ' Close the XmlTextWriter.
                .WriteEndDocument()
                .Close()
            End With
            MsgBox("Успешна регистрация! Благодарим Ви!")
            MainForm.РегистрацияToolStripMenuItem.Visible = False
        Else
        MsgBox("Невалиден сериен номер!")
        End If
    End Sub
    Public Sub Check_Reg(ByVal FileString As String)
        If (System.IO.File.Exists(FileString)) Then

            Dim document As XmlReader = New XmlTextReader(RegForm.RegFile)

            While (document.Read())

                Dim type = document.NodeType

                If (type = XmlNodeType.Element) Then

                    If (document.Name = "Registered") Then
                        If document.ReadInnerXml.ToString() = "True" Then
                            Registered = True
                        Else
                            Registered = False
                        End If

                    End If

                    If (document.Name = "SerialNumber") Then
                        SerialNumber = document.ReadInnerXml.ToString()
                    End If

                End If

            End While

        Else

            MessageBox.Show("The filename you selected was not found.")

        End If
    End Sub
End Class

Answer 1

is it because of that?! I don’t think so.

It’s exactly because of that.

You should always make sure to properly dispose IDisposable resources such as Streams and Writers/Readers by wrapping them in a Using block. In your case I don’t see you closing your reader. But if you wrap it in a Using block you shouldn’t worry about it. Even if an exception is thrown the resource will be properly released.

Example:

Using XmlWrt As XmlWriter = XmlWriter.Create(FileString, settings)
    ...
End Using

You should do the same with your XmlReader:

Using document As XmlReader = XmlReader.Create(RegForm.RegFile)
    ...    
End Using