There are plenty of java wiki engines http://java-source.net/open-source/wiki-engines
I'm currently looking for good lightweight wiki , something like the community wiki on stackoverflow , that can be easily integrated into excising applications. Please write about something that you have used.
I really like Mylyn WikiText: besides offering UI elements like an Eclipse editor, it offers API and Ant tasks for working with various wiki formats (Textile, MediaWiki, Confluence, Trac) and exporting to HTML, PDF, and others. It's available in Eclipse Galileo and as a standalone library (see bottom of the page).
I personally use JSP Wiki. It's lightweight, easy to use, and obviously uses Java. You just drop it in an application server, make some small config changes and you're golden! I set this up as my company's Wiki and it runs just great.
Consider FitNesse if this is in any way programming related. It allows you to write tests in the Wiki and have the testing framework update the Wikipages with the results. This allows others than programmers to collaborate on this.
Hi,
check out GWiki, http://labs.micromata.de/display/gwiki/Home it's great.