FreeForums
An XML based Java 2 Enterprise Forum Solution for webmaters. FreeForums uses CSS, DHTML and JavaScript for rendering pages and can be changed to suit the needs of every website. FreeForums also features a Desktop client for MS-Windows.

JavaBB
JavaBB is a software based on Java, developed specifically with intention to join communities. Based in phpbb, we are working pledged by the success of phpBB, to become javaBB so efficient as it.

JForum
JForum is a powerful and robust discussion board system implemented in Javatm. It provides an attractive interface, an efficient forum engine, an easy to use administrative panel, an advanced permission control system and much more.

JForumFusion
JForumFusion is a platform independent discussion board program. Some of it main features include: support of unlimited discussion forums, topics and member, threaded or linear discussions, file attachments, private messaging, web based administrative tools, UBBCode, multiple authentication sources, and high performance search engine.

JsForum
JsForum is a full J2EE forum (bulletin board), written in JSP and Servlets designed using the MVC (Model View Control) framework Struts. Because it's written in Java it's fully patform independent. Why an other bulletin board when there are alot of them? There are alot of different kind of bulletin boards like phpBB, but there are not so many bulletin boards which are written in Java.

mvnForum
mvnForum is an open source, powerful, easy to use, easy to setup bulletin board (forum) built on the Java J2EE technology (Jsp/Servlet). mvnForum is compatible with any Servlet Containers which supports Jsp 1.2 and Servlet 2.3. mvnFourm is free, opensource and released under the terms of the GNU General Public License. It means that you could use it free of charge to build your own discussion communities.

Nemesis-forum
A discussion forum using JAVA J2EE technologies. some Features:i18n Back-Office , users/groups/permissions management., Forum PRE AND POST Moderation , Content filters, integrated Search engine, Multi-databases support...

Sk Forum
SK Forum is an open source web-based J2EE forum application. But it's so much more, it's a comic system, an addressbook, a wiki, a timetracking system, a todo list, a poll system, a guestbook system and a few other small nuts and bolts.

Yazd
Yazd is an open-source (Apache License) discussion forum software that you can download customize and use. Yazd is a Java based forum software that can easily be configured through an admin interface. This discussion forum software is highly flexible and uses JDBC to connect to a backend database.