Visual Basic

Public Class FileInfoDateComparer
    Implements IComparer

Public Function Compare(ByVal x As Object, ByVal y As Object) As Integer _
    Implements System.Collections.IComparer.Compare

    ' Notice that Compare takes two Objects, not FileInfo objects.  Check
    ' to see if they are both FileInfo objects first.
    If TypeOf x Is FileInfo AndAlso TypeOf y Is FileInfo Then
        ' If they are, cast the Objects back to FileInfo objects
        ' so we can use them.
        Dim op1 As FileInfo = DirectCast(x, FileInfo)
        Dim op2 As FileInfo = DirectCast(y, FileInfo)
        Return op1.LastAccessTimeUtc.CompareTo(op2.LastAccessTimeUtc)
    Else
        ' Throw an ArgumentException here because both arguements were not FileInfo objects.
    End If
End Function

stableFiles.Sort(New FileInfoDateComparer)