Hi,

After selecting the folder which contains xml files gets validate and display errors in RichTextBox.
Here it showing error from one xml file, but there is one more xml file which contains error.
How would I display error from multiple xml files in richtextbox.

Private Sub btnFolderXMLFiles_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFolderXMLFiles.Click
        Dim foldername As String
        Dim filename As String
        If FolderBrowserDialog1.ShowDialog() = DialogResult.OK Then
            foldername = FolderBrowserDialog1.SelectedPath()
        Else
            Dim Results As DialogResult = FolderBrowserDialog1.ShowDialog
            If Results = DialogResult.Cancel Then
                Return
            End If
            Exit Sub
        End If
        txtFolderXMLFiles.Text = foldername
        validatexmls(foldername)
    End Sub

Private Function validatexmls(ByVal infile As String) As Boolean
        Dim filename As String
        Dim mydir As New DirectoryInfo(infile)
        Dim m_xmld As XmlDocument
        Dim f As FileInfo() = mydir.GetFiles("*.xml")
        Dim i, j As Integer

        For i = 0 To f.Length - 1
            filename = f(i).FullName
            ' create xml doc
            m_xmld = New XmlDocument
            m_xmld.Load(filename)

            'First we create the xmltextreader
            Dim xmlr As New XmlTextReader(filename)

            'We pass the xmltextreader into the xmlvalidatingreader
            'This will validate the xml doc with the schema file
            'NOTE the xml file it self points to the schema file

            Dim xmlvread As New XmlValidatingReader(xmlr)

            ' Set the validation event handler
            AddHandler xmlvread.ValidationEventHandler, AddressOf ValidationCallBack
            m_success = True 'make sure to reset the success var

            ' Read XML data
            While (xmlvread.Read)
            End While
            'Close the reader.
            xmlvread.Close()
        Next
        'The validationeventhandler is the only thing that would
        'set m_Success to false
        Return m_success
    End Function

Private Sub ValidationCallBack(ByVal sender As Object, ByVal args As ValidationEventArgs)
        'Display the validation error. This is only called on error
        m_success = False
        Dim mywriter As System.IO.TextWriter
        mywriter = System.IO.File.CreateText("ValidationError.log")
        mywriter.WriteLine("Validation error: " + args.Message)
        mywriter.Close()
        WriterBox.Text = ("Validation error: " + args.Message)
    End Sub

Thanks,
Shailesh

Problem has been solved!