I was trying to implement a simple cron scheduler which gets called at a particular time. It was working perfectly with 1 second or any other delay implementations with the end point. But if I try executing it for a particular time it is failing, and giving me java exception like the below. I am using Java play framework, which also has some parts written in Springboot

org.quartz.ObjectAlreadyExistsException: Unable to store Job : 'training.trainingReminderTrigger', because one already exists with this identification.     at org.quartz.simpl.RAMJobStore.storeJob(RAMJobStore.java:277)  at org.quartz.simpl.RAMJobStore.storeJobAndTrigger(RAMJobStore.java:249)    at org.quartz.core.QuartzScheduler.scheduleJob(QuartzScheduler.java:840)    at org.quartz.impl.StdScheduler.scheduleJob(StdScheduler.java:250)  at util.executor.SchedulerManager.startTrainingReminderScheduler(SchedulerManager.java:193)     at controllers.CommonController.startScheduler(CommonController.java:3044)  at Routes$$anonfun$routes$1$$anonfun$applyOrElse$757$$anonfun$apply$2267.apply(routes_routing.scala:9125)   at Routes$$anonfun$routes$1$$anonfun$applyOrElse$757$$anonfun$apply$2267.apply(routes_routing.scala:9125)   at play.core.Router$HandlerInvoker$$anon$7$$anon$2.invocation(Router.scala:183)     at play.core.Router$Routes$$anon$1.invocation(Router.scala:377)     at play.core.j.JavaAction$$anon$1.call(JavaAction.scala:56)     at util.Global$ActionWrapper.call(Global.java:355)  at play.core.j.JavaAction$$anon$3.apply(JavaAction.scala:91)    at play.core.j.JavaAction$$anon$3.apply(JavaAction.scala:90)    at play.core.j.FPromiseHelper$$anonfun$flatMap$1.apply(FPromiseHelper.scala:82)     at play.core.j.FPromiseHelper$$anonfun$flatMap$1.apply(FPromiseHelper.scala:82)     at scala.concurrent.Future$$anonfun$flatMap$1.apply(Future.scala:251)   at scala.concurrent.Future$$anonfun$flatMap$1.apply(Future.scala:249)   at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:32)     at play.core.j.HttpExecutionContext$$anon$2.run(HttpExecutionContext.scala:37)  at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:42)    at akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(AbstractDispatcher.scala:386)   at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)     at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)     at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)     at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)        

I am sharing my code implementation below,

##routes file
POST     /startScheduler                                @controllers.CommonController.startScheduler()
POST     /restartScheduler                              @controllers.CommonController.restartScheduler()

/* controller file */
public Result startScheduler() {
        try {
        SchedulerManager schedulerExample = new SchedulerManager();
        schedulerExample.startTrainingReminderScheduler();
        return ok("Scheduler started successfully!");
        } catch(Exception e) {
            return ok("Mission failed");
        }
    }
    
    public Result restartScheduler() {
        
        try {
        SchedulerManager schedulerExample = new SchedulerManager();
        schedulerExample.restartTrainingReminderScheduler();        
        return ok("Scheduler stopped and restarted successfully");
        } catch(Exception e) {
            e.printStackTrace();
        }
          return ok("Mision Failed");
    }

/* Scheduler service implementation */  
public static void startTrainingReminderScheduler() {
        try {
            JobDetail enrolledTrainingReminderjob = JobBuilder.newJob(EnrolledTrainingReminderJob.class)
                    .withIdentity("trainingReminderTrigger", "training")
                    .build();

          
         Trigger enrolledTrainingReminderJobTrigger = TriggerBuilder.newTrigger()
                    .withIdentity("trainingReminder", "training")    
                    .withSchedule(CronScheduleBuilder.cronSchedule("0 05 11 ? * FRI,SUN *"))         
                    .build();     

            try {
                Scheduler scheduler = new StdSchedulerFactory().getScheduler();
                scheduler.start();
                scheduler.scheduleJob(enrolledTrainingReminderjob, enrolledTrainingReminderJobTrigger);
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    
    
    public static void restartTrainingReminderScheduler() {
        try {
        Scheduler scheduler = new StdSchedulerFactory().getScheduler();
        scheduler.standby();
        scheduler.shutdown(true);
        
        scheduler = new StdSchedulerFactory().getScheduler();
        scheduler.start();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

/* cron job executor */
package util.executor.job;


import java.time.LocalDate;
import java.time.LocalTime;
import java.time.ZoneId;
import java.util.ArrayList;
import java.util.List;

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

import data.dao.MongoBaseDao;

public class EnrolledTrainingReminderJob extends MongoBaseDao implements Job {

    static List<String> trainingDetails = new ArrayList<>();

    static ZoneId zoneTime = ZoneId.of("Asia/Kolkata");        
    static LocalTime currentTime = LocalTime.now(zoneTime);
    static LocalDate currentDate = LocalDate.now(zoneTime); 
    
    @SuppressWarnings("all")
    public void getAllCurrentTrainings() {
        
        trainingDetails.add("Java");
        trainingDetails.add("python");
    }

    @Override
    public void execute(JobExecutionContext context) throws JobExecutionException { 
        getAllCurrentTrainings();
        System.out.println("These are the trainings scheduled today");
        System.out.println(trainingDetails);
        
    }
}

I am able to send messages with this executor job for delay based execution..But I am getting the exception if I try to execute the endpoint for a particular time. It does not execute automatically if I hit the endpoint before the cron expression time, if I manually hit the endpoint in the time which matches with cron expression time implementation, it gives me quartz exception. I am not able to debug it. I am not sure if it is the issue in my implementation or issue in my approach of testing it.