Somebody asked about .NET-based forum software here:
Now I have a similar question but I prefer Java. I'm interested in building a community site so I'd like to know my options. It doesn't have to be free but it needs to be something a normal engineer can afford. Thanks!
Update: I prefer a Java-based solution because I'm a Java developer and I figure that it would be easier for me to customize it or modify its code when necessary. I know that PHP forums such as phpBB and vBulletin are very popular but I wouldn't want to touch PHP code.