ButorWiki
This is a Java based wiki. It is a web-app using Butor Java Framework and struts MVC framework. ButorWiki use a filesystem folders and files to store everything. No database are needed.

Chiki
Chiki is an Open Source Web-based Community building tool. Use Chiki to build communities where all users can contribute as easily as writing an email. Content can be created and edited using any web browser. There is no need to know HTML or to upload pages with FTP or HTTP as with traditional web pages.

FitNesse
FitNesse is a wiki web server. A wiki allows any authorized user to make changes to any edit-enabled page, or to create new pages, simply by using their Web browser.

JSPWiki
This Wiki is done using JSP technology, which hopefully makes it very easy to keep up to date, since the content and the presentation are separated. For the administrator it is easy to make your Wiki look any way you want. A custom bean handles the translation of text into HTML. The source code for JSPWiki is available.

Platypus Wiki
Platypus Wiki is a project to develop an enhanced Wiki Wiki Web with ideas borrowed from the Semantic Web. It offers a simple user interface to create wiki pages with metadata based on W3C standards. It uses RDF (Resource Description Framework), RDF Schema and OWL (Web Ontology Language) to create ontologies and manage metadata.

Usemodj Wiki
UseModj is a Java based Wiki Clone, using Struts, Velocity Layout, CSS. It's goal is to be the same function and file storage as UseMod wiki, but is deployed by dropping a single war file into Tomcat or JBoss Server and supports file/image attach.

VeryQuickWiki
Very Quick Wiki is a WikiWiki web clone written using JSPs and JavaServlets and designed to install and run with minimum effort on Tomcat or some other Java application server.

XWiki
A Wiki or WikiWiki is a website allowing users to add content, as on an Internet forum, but also allows anyone to edit the content. XWiki is a WikiWiki clone written in Java which supports many popular features of other Wikis.

yawiki
This is yet another java implementation of such a wiki system. A wiki system is a perfect place for working together and sharing informations. The syntax for the wiki system is really simple to learn. Getting started with
a wiki system is easy.