How do I handle the back button of the browser in servlet environment.

[Ashish Adhiya]

Hi all,   I have a different servlets which does the different functions such as add, modify, delete & view. At the end of each function, the session arributes gets removed.   One can try click on the back button of the browser & view the cached version of pages and also may click on some functional buttons. Since the all the session buttons are removed, on click of functional button gives me the null pointer exception.   Please suggest me the general approach to handle this kind of scenario.   Thanks in advance, Ashish.