sorting listview only works once

Question

I have a listview that I use the ListViewItemComparer Class.  I have set it to statically call the sort set to column 0.  I also have a timer that checks the source for the list for changes and updates every 5 seconds.

The first time I make the call all columns sort, as advertised, but each subsequent sort only plugs in the last row completely, all others only have column 0 filled in, the other two columns are blank.

I am thinking (a dangerous thing) that the repeated sorts are the problem and I need to reset the listview sort back to original before sorting again, but am not sure that is it or how to go about it. I have attached the code. 

Thanking you all in advance.

    Private Sub listTorrents()
        Dim tb As New uTToolBoxManager(uThttpAddress, uTuserName, uTpassword)
        tb.Authenticate()
        If pingCount >= 5 Then Exit Sub
        lvActiveTorrents.Items.Clear()
        If uTError = 1 Then
            Exit Sub
        End If
        Dim i As Integer = 0
        Dim ratio As Integer = 0
        Dim torrents = tb.GetCompletedFilesPerRatio(ratio)
        For Each torrent In torrents
            lvActiveTorrents.Items.Add(torrent.Name)
            lvActiveTorrents.Items(i).SubItems.Add(CStr(torrent.Ratio & " %"))
            lvActiveTorrents.Items(i).SubItems.Add(CStr(Round((torrent.Downloaded / torrent.Size) * 100) & "%"))
            i = i + 1
        Next
        lvActiveTorrents.ListViewItemSorter = New ListViewItemComparer(0)
    End Sub

    Class ListViewItemComparer
        Implements IComparer

        Private col As Integer

        Public Sub New()
            col = 0
        End Sub

        Public Sub New(ByVal column As Integer)
            col = column
        End Sub

        Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
            Return [String].Compare(CType(x, ListViewItem).SubItems(col).Text, CType(y, ListViewItem).SubItems(col).Text)
        End Function

    End Class

Answer 1

hi,

Is your listview data bounded?

Refer to: http://vbcity.com/forums/t/164556.aspx

Answer 2

_Omar - no it is not, however I  figured out how to fix, was ridiculously simple and overlooked it.

I simply added this:

lvActiveTorrents.ListViewItemSorter = Nothing  
before this line
lvActiveTorrents.Items.Clear()

 Thanks for helping though, your link is useful for another project!

Answer 3

I can not reproduce the problem: (add a listview and a button to the form)

Public Class Form1

   Private Class Sorter
      Implements IComparer

      Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer Implements System.Collections.IComparer.Compare
         Dim item1 = DirectCast(x, ListViewItem)
         Dim item2 = DirectCast(y, ListViewItem)

         Return item1.Text.CompareTo(item2.Text)

      End Function
   End Class

   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

      Dim rnd As New Random

      Dim newItems = From i In Enumerable.Range(1, 10) _
                     Select New ListViewItem With {.Text = Chr(65 + rnd.Next(0, 26))}

      ListView1.Items.Clear()
      ListView1.Items.AddRange(newItems.ToArray)
      ListView1.ListViewItemSorter = New Sorter

   End Sub

End Class

Every time I click the button, new items are created and correctly sorted without previously setting ListViewItemSorter to Nothing .

You've mentioned a timer in your first post. Which kind of timer? A System.Windows.Forms.Timer? What makes me sceptic is that you write "all others only have column 0 filled in, the other two columns are blank", which does not seem only to be a sorting problem.(?)

---

Armin

Answer 4

Armin,

Yes, it is a forms.timer. I have tried other sort methods and no go. I can only surmise it has something to do with the timer calling the sub-routine. Add the ListViewItemSorter = Nothing, it works, take it out, it doesn't work.

Go figger..

Thanks for your response.

Answer 5

Then I think this is cleaner code

    Private Sub listTorrents()
        Dim tb As New uTToolBoxManager(uThttpAddress, uTuserName, uTpassword)
        tb.Authenticate()
        lvActiveTorrents.ListViewItemSorter = New ListViewItemComparer(0)
        If pingCount >= 5 Then Exit Sub
        lvActiveTorrents.Items.Clear()
        If uTError = 1 Then
            Exit Sub
        End If
        Dim i As Integer = 0
        Dim ratio As Integer = 0
        Dim torrents = tb.GetCompletedFilesPerRatio(ratio)
        For Each torrent In torrents
            lvActiveTorrents.Items.Add(torrent.Name)
            lvActiveTorrents.Items(i).SubItems.Add(CStr(torrent.Ratio & " %"))
            lvActiveTorrents.Items(i).SubItems.Add(CStr(Round((torrent.Downloaded / torrent.Size) * 100) & "%"))
            i = i + 1
        Next
        End

---

Success
Cor

Answer 6

Cor - except it doesn't work.