Android Question Work with substring

Dim s As String = $"https://www.test.com/mysite/test.html"$
    
Dim result() As String = Regex.Split("/", s)

If result.Length > 0 Then
    Log(result(result.Length - 1))
End If

    Private s As String = "https://www.test.com/mysite/test.html"
    Private i As Int
    Private r As String
    i = s.LastIndexOf("/")
    r = s.SubString(i + 1)
    Log(r)

    Dim Text As String = $"https://www.test.com/mysite/test.html"$
    Dim Pattern As String = $"\/([^\/?#]+)(?:[?#]|$)"$
    Dim Matcher1 As Matcher = Regex.Matcher(Pattern,Text)
    If Not (Matcher1.Find) Then Return
    Log(Matcher1.Group(1))

Dim S As String = "https://www.test.com/mysite/test.html"
Log(File.GetName(S))

Dim S As String = "https://www.test.com/mysite/test.html"
Log(S.Replace("https://www.test.com/mysite/", ""))