VB.NET Excel Program Leaves EXCEL.EXE floating after completion

Question

I am writing a program that loops through all of the sheets in an Excel workbook and saves each sheet as its own workbook. It turned out to be a bit trickier than I expected

Answer 1

Below is code that works for me (NOTE order that I release objects, which is important)

xlWorkBook.Close()
xlApp.Quit()
ReleaseObject(xlWorkSheet)
ReleaseObject(xlWorkBook)
ReleaseObject(xlApp)

Private Sub ReleaseObject(ByVal obj As Object)
  Try
    System.Runtime.InteropServices.Marshal.ReleaseComObject(obj)
    obj = Nothing
  Catch ex As Exception
    obj = Nothing
  Finally
    GC.Collect()
  End Try
End Sub

Answer 2

Okay, this works form me for a very simple worksheet. Let me know if you have any questions.

Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
    'Get information from text boxes
    Dim InputLocation As String
    Dim OutputLocation As String

    InputLocation = InputLoc.Text & "\" & Filename.Text

    If OutputLoc.Text = "" Then
        OutputLocation = InputLoc.Text
    Else
        OutputLocation = OutputLoc.Text
    End If

    'Make file to save files in
    ' Get date and time in filename as well
    Dim TLDateTime As String
    Dim TLDay As String
    Dim TLMonth As Integer
    Dim TLYear As Integer
    Dim TLHour As Integer
    Dim TLMinute As Integer
    Dim TLDate As String
    Dim TLTime As String
    Dim TLSecond As Integer

    TLDay = DateTime.Now.Day
    TLMonth = DateTime.Now.Month
    TLYear = DateTime.Now.Year
    TLHour = DateTime.Now.Hour
    TLMinute = DateTime.Now.Minute
    TLSecond = DateTime.Now.Second

    Dim MyDate As New DateTime(TLYear, TLMonth, TLDay, TLHour, TLMinute, TLSecond)
    Dim MyString As String = MyDate.ToString("MMMddyyyy_HHmmss")
    TLDate = TLMonth.ToString + TLDay.ToString + TLYear.ToString
    TLTime = TLHour.ToString + TLMinute.ToString
    TLDateTime = TLDate + "_" + TLTime

    Try
        Directory.CreateDirectory(OutputLocation & "\" & "Field Sales Report Graphs " & TLDateTime)
        OutputLocation = OutputLocation & "\" & "Field Sales Report Graphs " & TLDateTime
    Catch
        MsgBox("Trying to create a file that exists, please delete it. If the file does not exist check to make sure your output location exists")
    End Try

    'Open up excel file with information in it
    Dim xlApp1 As Excel.Application = New Excel.Application
    xlApp1.Visible = True
    xlApp1.Application.DisplayAlerts = False

    Dim locs As Excel.Workbook
    locs = xlApp1.Workbooks.Open(InputLocation)
    Dim fileNames As New ArrayList
    Dim counter As Integer = 1
    For Each ws As Excel.Worksheet In locs.Worksheets
        fileNames.Add(ws.Name)
        ws = xlApp1.Workbooks(counter).Sheets(1)
        ws.SaveAs(Filename:=OutputLocation & "\" & fileNames(counter - 1) & ".xlsx")
        'close excel and release com objects
        System.Runtime.InteropServices.Marshal.ReleaseComObject(ws)
        xlApp1.Workbooks(counter).Close(False)
        counter += 1
    Next
    System.Runtime.InteropServices.Marshal.ReleaseComObject(locs)
    locs = Nothing
    xlApp1.Quit()
    System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp1)
    xlApp1 = Nothing
End Sub

Answer 3

You might need to do the following if you have unreferenced COM objects that are being created:

GC.Collect()
GC.WaitForPendingFinalizers()

Taken from this MSDN forum post: http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/cb5f7948-c229-483e-846b-a1cfbbcd86ca/

Answer 4

The solution I finally came across was to add

System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp1.ActiveWorkbook)
xlApp1.ActiveWorkbook.Close()

to the loop. I found this answer in the comments of The first answer on another stack overflow post. Basically, the problem I was having is that the worksheet.copy method creates a workbook object with no reference, but it turns out it can be referenced by referring to the activesheet. If you wanted to do more with it than just kick it out the door like I am, I imagine you could create a new workbook object and assign it or as the post I link to suggests, you can save it as something as well. For my puposes, it is just fine to release it after saving the worksheet I want and this removed my excel.exe hanging process.

If you want a bit more elgant code option you should check out the ron tornambe post where he does the for each loop I managed to not get right instead of the wonky thing I create. Basically you would want to use his loop in my code and you would have it all set up. Thanks as always stack overflow.