All the Jobs registered in the Quartz Scheduler are uniquely identified by the JobKey which is composed of a name and group . You can fire the job which has a given JobKey immediately by calling triggerJob(JobKey jobKey) of your Scheduler instance.
//Create a new Job
JobKey jobKey = JobKey.jobKey("myNewJob", "myJobGroup");
JobDetail job = JobBuilder.newJob(MyJob.class).withIdentity(jobKey).storeDurably().build();
//Register this job to the scheduler
//Immediately fire the Job MyJob.class
scheduler is the Scheduler instance used throughout your application . Its start() method should be already called after it is created.
The job is the durable job which cannot attach any triggers or cron to it .It can only be fired programmatically by calling triggerJob(JobKey jobKey).