cron4j is a scheduler for the Java platform which is very similar to the UNIX cron daemon. With cron4j you can launch, from within your Java applications, any task you need at the right time, according to some simple rules.
Programming the cron4j scheduler is easy, you have to know just a few methods. The launching rules for every task must be expressed with a string called scheduling pattern, whose syntax is equal to the one used by the UNIX crontab entries. If you know how to manipulate the UNIX crontab, the most is done.