How to reverse "?<=" in regexp : when I use:

            String s = "http://google.com, /home/roroco/Dropbox/jvs/ro-idea/META-INF/plugin.xml"
            ArrayList<String> ms = s.findAll(/(?<=\/)\/\S+/)
            println(ms)

the output:

    [/google.com,]

when I change to:

    s.findAll(/(?<!\/)\/\S+/)

        
the output:

    [//google.com,, /home/roroco/Dropbox/jvs/ro-idea/META-INF/plugin.xml]

In my understand, `/(?<!\/)\/\S+/` output should be same with `/(?<=\b)\/\S+/` output but in fact, i'm wrong, why? 