Create Sitemap Using Java Tutorial describes about creating sitemap using java

It will also support for google site map updations

Sitemap is an easy manner for a webmasters to notify search engine spiders about pages on their sites that are accessible for crawling and indexed.

Sitemap is a simple XML file that consists of list of Entries (URLs) of a website along with some other details about URL like URL last updated time, how often URL updated ( ie; change frequency of URL) and how vital it is ( ie; priority of URL)

so that by using these informations search engines spiders can able to crawl the site.