I have a program that lists files found from a search, and when the user selects one of the files and clicks open, it will open the file they've selected. I only want them to be able to open one file at a time, and I want an error box to show if they click Open without selecting a file...does anyone know what error I can use or what kind of conditioning I can use to make this happen? This is what I have:

Private Sub OpenBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles OpenBtn.Click
            For Each file As ListViewItem In FilesList.Items
                Dim filePath As String = file.SubItems(1).Text & "\" & file.Text
                If file.Selected = True Then
                End If
        Catch ex1 As System.ComponentModel.Win32Exception
            MessageBox.Show("Unable to identify a program with which to open this file.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
          End Try
    End Sub

Hi, Use ListView1.SelectedItems instead of ListView1.Items. If ListView1.SelectedItems.Count =0 then There is nothing selected otherwise something selected.

If you want the user should select only one then Change MultiSelect Property to False.