The approach to searching depends a lot on what you want to search - a database, a collection of static web pages, a collection of document files (like Word, PDF, ...), a collection oy dynamic web pages, ...
There are Java libraries that can help with any of these. A good one is Jakarta Lucene, which can create and search indexes of searchable stuff. The Nutch project built on top of Lucene indexes and searches web pages.
If it's a public website, you could also simply add a google search to the site (see the side bar at http://www.javaranch.com).
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
subject: Implementing the search functionality in java applications