What's the URL you see in your address bar?
Like,
http://hostname:port/proj/helloworld
or
http://hostname:port/helloworld
It all depends on your action attribute of form element in your
JSP. If it doesn't contain a leading '/', the former would result. On the contrary, if it does contain a leading '/', the latter would result, which isn't obviously the desired one. I'd advise you to use
in your JSP.
Also you don't need to write to a file for checking if a section of code is reached, you could use Sysouts, loggers or even debug with
IDE.