Essiembre J2EE Scheduler
J2EE Scheduler is a simple task scheduling mechanism for J2EE applications. This library can be considered a wrapper around the Timer and TimerTask classes found in the standard Java API. Configuration for tasks to be executed and their frequency is XML-based.

Fulcrum Scheduler
This component provides a scheduler service.

Gos4j
Gos4j is a way of organising processing priorities based on goals. Each goal is processed based on its time to complete, and its progress towards that goal. Deadlines are used to act as the target completion time for a goal, and can be expressed in either relative or absolute terms.

jcrontab
Jcrontab is a scheduler written in java. Jcrontab is designed to be extended and integrated with any project. Reads and stores the tasks to execute in a file, a database or an EJB and provides a web UI and a basic swing GUI.

Quartz
Quartz is an open source job scheduling system that can be integrated with, or used along side virtually any J2EE or J2SE application. Quartz can be used to create simple or complex schedules for executing tens, hundreds, or even tens-of-thousands of jobs; jobs whose tasks are defined as standard Java components or EJBs.