what is the error i am getting in this program

package com.quartzsche;

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

public class TestSchedule {
public static void main(String[] args) throws Exception {


JobDetail job = JobBuilder.newJob()
.withIdentity("dummyJobName", "group1").build();

Trigger trigger = TriggerBuilder
.newTrigger()
.withIdentity("dummyTriggerName", "group1")
.withSchedule(
SimpleScheduleBuilder.simpleSchedule()
.withIntervalInHours(1).repeatForever())
.build();


Scheduler scheduler = new StdSchedulerFactory().getScheduler();
scheduler.start();
scheduler.scheduleJob(job, trigger);

}
}


I have written a program using quartz scheduler for output to trigger every one hour...

When I run this program i am getting the following error:

Exception in thread "main" java.lang.IllegalArgumentException: Job class cannot be null.
at org.quartz.impl.JobDetailImpl.setJobClass(JobDetailImpl.java:307)
at org.quartz.JobBuilder.build(JobBuilder.java:103)
at com.quartzsche.TestSchedule.main(TestSchedule.java:16)


may I know what is this.

Best,
Sudheep.