cron4j

cron4j is a scheduler writtten in Java, similar to the original 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.

The Java 2 platform already has a built-in scheduler, implemented with the class java.util.Timer. The cron4j scheduler, however, acts in a different way. You can say to the java.util.Timer scheduler something like "launch this task after 5 minutes from now" or "launch it after 5 minutes from now, then repeat it every 10 minutes". That's all. The cron4j scheduler, instead, lets you do something a little more complex, like "launch this task every Monday, at 12:00", "launch it every 5 minutes, but don't launch it during the weekend", "launch it every hour between the 8:00AM and the 8:00PM and launch it every 5 minutes between the 8:00PM and the 8:00AM", "launch it once every day but Sunday, during every month but July and August" and so on, and all that with a single line of code.

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. If you can't, don't worry: crontab scheduling patterns rules are very simple and you can learn them in minutes. By the way, you will find them explained in the cron4j documentation.

What is new in this release:

• The setTimeZone() method has been added to the Predictor class.
• A bug causing a rare deadlock condition while shutting down the scheduler has been fixed.

What is new in version 2.2.4:

• Fixed a bug in the ProcessTask class.

What is new in version 2.1.1:

• The step values parser has been changed to be more compliant with the majority of cron implementations.
• Now, "a-b/c" means "took a value every c elements in the range a-b", and no longer "took every element within the a-b range whose value can be divided by c". For example, "2-12/5" now means "2,7,12", while before it was "5,10".
• TimerThread instances are now spawned as daemon threads if the scheduler has been set to act as a daemon with the setDaemon(true) method.

What is new in version 2.0.1:

• The SchedulingPattern parser has been rewritten to be 100% compliant with the UNIX crontab specification. (Thanks to Paul Logan)

What is new in version 2.0:

• New task abstraction layer
• Task collectors
• Task executors
• Scheduling from files
• Cron parser
• Support for different Time Zones
• A new event driven API

Requirements:

• Java 2 Standard Edition Runtime Environment