How to use Java Constant as a part of @Scheduler expression annotation in Spring?

Question

I am using Spring scheduler as given bellow.

 @Scheduled(fixedDelay = ((10 * 60 * 1000) / 2))
    public void runDynamic()
    {
      //doing my stuff
    }

Now suppose I have one constant like this

public static final Integer VARIANCE_TIME_IN_MIN = 10;

And I want to use this constant as a part of my expression something like this :

@Scheduled(fixedDelay = ((MyConstants.VARIANCE_TIME_IN_MIN * 60 * 1000) / 2))
public void runDynamic()
{
//doing my stuff
}

but it is giving my compile time error. Any ideas? Thanks in Advance..!

Answer 1

Java annotations take compile time constants, which are defined as final primitives or strings.

SO change your definition to

   public static final int VARIANCE_TIME = 10;
   public static final long FIXED_DELAY = ((VARIANCE_TIME * 60 * 1000) / 2)

   @Scheduled(fixedDelay = FIXED_DELAY)
   public void runDynamic()      

Answer 2

Use Task scheduling using cron expression from properties file

@Scheduled(cron = "${cronTrigger.expression}")
public void runDynamic()
    {
      //doing my stuff
    }

Config in XML File:

<bean id="cronTrigger" class="org.springframework.scheduling.quartz.CronTriggerBean">
    <property name="jobDetail" ref="exampleJob" />
    <!-- run every morning at 6 AM -->
    <property name="expression" value="0 0 6 * * ?" />
</bean>

This link1 and doc might help you

You can also create the Tash Scheduler dynamically(programatically) as explained here

Answer 3

private static final long VARIANCE_TIME_IN_MIN = 10l;

@Scheduled(fixedDelay = ((VARIANCE_TIME_IN_MIN * 60 * 1000) / 2))
public void runDynamic() {
    // ...
}