Quartz Scheduler :Scheduling Job in Java

• For a scheduled job in java we have three main components JOB,TRIGGER,SCHEDULER.
• Quartz Scheduler is one of the API in java provides scheduling a job.
• The Library can be downloaded from :-

           http://quartz-scheduler.org/downloads

• The required jar files are :-

           quartz-2.1.6.jar,
           quartz-all-2.1.6.jar,
           quartz-commonj-2.1.6.jar,
           slf4j-api-1.7.2.jar,
           slf4j-simple-1.7.2.jar

Project Structure:-

Quartz Configuration:-

org.quartz.scheduler.instanceName = MyScheduler
org.quartz.threadPool.threadCount = 3
org.quartz.jobStore.class = org.quartz.simpl.RAMJobStore

Quartz Job Class:- 

package com.sandeep.quartz.scheduler;

import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
import org.quartz.JobKey;

public class DemoJob  implements Job{

 @Override
 public void execute(JobExecutionContext context) throws JobExecutionException {
  
  JobKey jobKey = context.getJobDetail().getKey();

   System.out.println("Hi This is a demo job "+jobKey);
 }

}

Creating and Scheduling job:-

• This job will be called in every 3 seconds.

package com.sandeep.quartz.scheduler;

import static org.quartz.JobBuilder.newJob;
import static org.quartz.SimpleScheduleBuilder.simpleSchedule;
import static org.quartz.TriggerBuilder.newTrigger;
import org.quartz.JobDetail;
import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.SchedulerFactory;
import org.quartz.Trigger;
import org.quartz.impl.StdSchedulerFactory;

public class QuartzSchedulerDemo {

 public static void main(String[] args) {

  JobDetail demoJob = newJob(DemoJob.class)
    .build();

  Trigger trigger = newTrigger()
    .withIdentity("SandeepDemoTrigger")
    .withSchedule(
      simpleSchedule().withIntervalInSeconds(3)
        .repeatForever()).build();

  SchedulerFactory sf = new StdSchedulerFactory();
  Scheduler sched;
  try {
   sched = sf.getScheduler();
   sched.scheduleJob(demoJob, trigger);
   sched.start();

  } catch (SchedulerException e) {
   e.printStackTrace();
  }

 }

}

Output:-

Hi This is a demo job DEFAULT.6da64b5bd2ee-a297d774-ea8a-4569-b70c-24f22706e15d
Hi This is a demo job DEFAULT.6da64b5bd2ee-a297d774-ea8a-4569-b70c-24f22706e15d
....