retrieving contents from multiple doc file and saving to a new doc file using vb.net

 Imports System.Windows.Forms
Imports word = Microsoft.Office.Interop.Word
Imports Microsoft.Office.Interop.Word
Imports System.Runtime.InteropServices

Public Class Form1
    Dim flb As New System.Windows.Forms.FolderBrowserDialog
    Dim fod As OpenFileDialog = New OpenFileDialog()
    Dim objapp As New word.Application
    Dim objdoc As New word.Document
    Dim object1 As Object
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        flb.RootFolder = Environment.SpecialFolder.MyComputer
        flb.ShowNewFolderButton = False
        Dim result As DialogResult = flb.ShowDialog
        If (result = DialogResult.OK) Then
            ListBox1.Items.Clear()
            TextBox1.Text = flb.SelectedPath
            For Each filename In Directory.GetFiles(flb.SelectedPath, "*.doc").Union(Directory.GetFiles(flb.SelectedPath, "*.rtf").ToArray())
                             
            Next
        End If
    End Sub
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
 Call readandwrite()

    End Sub
    Sub readandwrite()

        Dim missing As Object = System.Reflection.Missing.Value
        Dim oFals As Object = False
        Dim oTru As Object = True
        
        Dim obj1 As Object
        obj1 = TextBox1.Text & "\sam1"


         Try
        objapp = New word.Application
        objdoc = New word.Document

        If ListBox1.Items.Count > 0 Then

            For i As Integer = 0 To ListBox1.Items.Count - 1
                Dim obj As Object = ListBox1.Items(i)
                
                objdoc = objapp.Documents.Open(obj, missing, oTru, missing)
                objapp = New word.Application
                objdoc = New word.Document

                objdoc = objapp.Documents.Add(obj)
                
                objdoc.SaveAs(obj1)

              

                objdoc.Activate()
                objdoc.Close()
                objapp.Quit()


                objdoc = Nothing
                objapp = Nothing

            Next



        End If
        Catch ex As Exception
         MsgBox("read error")
         End Try

    End Sub