When practicing continuous delivery with Java it may be a problem if you have downtime every time you deploy to production. Your goal is to deploy as often as you can, so this is a problem you need to solve.
This video shows how you can avoid downtime when deploying Java web applications. It shows how to deploy (and roll back) new versions of your web application, and also how to handle database schema changes (and roll back) between deployments.
Video producer: http://www.boosterconf.no/