Java Programming

I have a JSP where im setting one of the hidden parameter as null after doing something and when the form is submitted i call my Processview which check for the form element value like this
if (form_element != null) {
my code
}
But this condition fails and went inside . So i tried like this
if(form_element != null && !form_element .equals("null")) {
my code
}

and here is succeeds. What could be the reason?

I have already raised a similar kind of doubt under the sub name
Null Reference vs Null String