Java @Schedule Example

@Schedule

For example, you are writing code to use a timer service that enables you to run a method at a given time or on a certain schedule, similar to the UNIX cron service. Now you want to set a timer to run a method, doPeriodicCleanup, on the last day of the month and on every Friday at 11:00 p.m. To set the timer to run, create an @Schedule annotation and apply it twice to the doPeriodicCleanup method. The first use specifies the last day of the month and the second specifies Friday at 11p.m., as shown in the following code example:

@Schedule(dayOfMonth="last")
@Schedule(dayOfWeek="Fri", hour="23")
public void doPeriodicCleanup() { ... }

The previous example applies an annotation to a method. You can repeat an annotation anywhere that you would use a standard annotation. For example, you have a class for handling unauthorized access exceptions. You annotate the class with one @Alert annotation for managers and another for admins:

@Alert(role="Manager")
@Alert(role="Administrator")
public class UnauthorizedAccessException extends SecurityException { ... }

For compatibility reasons, repeating annotations are stored in a container annotation that is automatically generated by the Java compiler. In order for the compiler to do this, two declarations are required in your code.