在VB.net中比较可以为空的DateTime

Dim date1 As DateTime? = DateTime.Now
Dim date2 As DateTime? = DateTime.Now.AddDays(1)

If date1.HasValue AndAlso date2.HasValue Then
    If date1.Value > date2.Value Then
        Console.WriteLine("date1 is greater than date2")
    ElseIf date1.Value< date2.Value Then
        Console.WriteLine("date1 is less than date2")
    Else
        Console.WriteLine("date1 is equal to date2")
    End If
Else
    Console.WriteLine("One or both dates are null")
End If