Get file name from URI string in C#

I have this method for grabbing the file name from a string URI. What can I do to make it more robust?

private string GetFileName(string hrefLink)
{
    string[] parts = hrefLink.Split("https://stackoverflow.com/");
    string fileName = "";

    if (parts.Length > 0)
        fileName = parts[parts.Length - 1];
    else
        fileName = hrefLink;

    return fileName;
}