I have to minimize the use of JavaScript in a portal.
what is the other alternative if we have to replace JavaScript code in a JSP????
Javascript is used for various purposes like Opening and closing new window, form submit and browser settings...
For validating form fields one alternative which i thought of is using java classes for it.
Can any suggest something else..

You don't really have a choice when it comes to opening and closing new windows. For form submissions, you can certainly use the old <input type="submit"/> element and you can just wait to validate the data when the form is submitted instead of doing any of it client-side. You can't really access a lot of browser settings from server-side logic, but you can at least get the user-agent string.

Nicholas C. Zakas
Author, Professional JavaScript for Web Developers (ISBN 0764579088)
http://www.nczonline.net/