Quartz Scheduler(Using Maven)

Today we will be discussing about Quartz Scheduler in Java. For that we are going to need a couple of Quartz jars. But, As I will be developing the project using Maven Build tools, I am not downloading it.
So, let's start with creating a Maven project for Quartz.

Step 1 : Create a Maven Project.
       a. Set up Maven in your eclipse. If you don't know how to set up Maven in Eclipse, have a look at              this tutorial - Setup Maven in Eclipse .
       b. Create a new Maven Project with whatever name you want. If you don't know how to create a
           Maven project in Eclipse, visit this link - Create a simple Maven project

Now, your maven project is ready to implement a Quartz Scheduler. But, for that, we need to add a couple of dependencies in our pom.xml.

Step 2: Add dependencies for Quartz in pom.xml. 
Add the following dependencies in your pom.xml.    

        
   org.quartz-scheduler
   quartz
   2.2.1
  
  
   org.quartz-scheduler
   quartz-jobs
   2.2.1
  

Now, we need to create two classes.

1) The class which is a Job. This class implements Job interface.
And
2) The main class which contains public static void main(String args[]) and calls the Job every 1 second.

Step 3:  Create Job Class. We are here trying to create a Job which prints  a simple string , e.g - "My First Quartz scheduler".

import org.quartz.Job;
import org.quartz.JobExecutionContext;
import org.quartz.JobExecutionException;
 
public class MyQuartzJob implements Job
{
 public void execute(JobExecutionContext context)
 throws JobExecutionException {
 
  System.out.println("My First Quartz Scheduler"); 
 
 }
 
}

This execute method is actually a method from Job Interface which we have implemented in our own way.
Step 4: Create a Main Class. This class will call the Job to execute after every 1 second.

import org.quartz.CronScheduleBuilder;
import org.quartz.JobBuilder;
import org.quartz.JobDetail;
import org.quartz.Scheduler;
import org.quartz.SchedulerException;
import org.quartz.Trigger;
import org.quartz.TriggerBuilder;
import org.quartz.impl.StdSchedulerFactory;

public class MainClass {

 public static void main(String[] args) throws SchedulerException {
  
  JobDetail job = JobBuilder.newJob(MyQuartzJob.class)//mention the Job Class Name here
       .build();
  
                //create schedule builder
  CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule("0/1 * * * * ?");
  
                //create trigger which the schedule Builder
  Trigger trigger = TriggerBuilder
    .newTrigger()
    .withSchedule(scheduleBuilder)
    .build();
  
        //create scheduler 
     Scheduler scheduler = new StdSchedulerFactory().getScheduler();

        // start your scheduler
     scheduler.start();
     
        // let the scheduler call the Job using trigger
     scheduler.scheduleJob(job, trigger);
 }

}

This is the code fragment where we mention the frequency of the scheduler to call the Job -

CronScheduleBuilder scheduleBuilder = CronScheduleBuilder.cronSchedule("0/1 * * * * ?");

("0/1 * * * * ?") is the cron expression for the frequency. For creating the schedules like this or may for customizing this, you can refer to this site - cronmaker.com.

Now, let's do maven compile & run our code.

The code will print the String "My FIrst Quartz Scheduler" in the console every 1 second like this -

My First Quartz Scheduler
My First Quartz Scheduler
My First Quartz Scheduler
My First Quartz Scheduler

......

Download the sample project in .zip here