Scheduling in Java.

Heads-up: Java cron ≠ Unix cron

Both Spring and Quartz use a 6-field cron expression that starts with seconds:

# Unix cron (5 fields)
min hour dom mon dow
0   9    *   *   1-5

# Spring / Quartz (6 fields — seconds first!)
sec min hour dom mon dow
0   0   9    *   *   MON-FRI

• Quartz day-of-week is 1-7 (1 = Sunday), and exactly one of day-of-month / day-of-week must be ?.
• Spring day-of-week is 0-7 (0 or 7 = Sunday) or MON-SUN, and supports L, W, #.

Spring @Scheduled

@Component
public class Jobs {

    // every weekday at 09:00 (sec min hour dom mon dow)
    @Scheduled(cron = "0 0 9 * * MON-FRI", zone = "UTC")
    public void report() {
        // ...
    }

    // every 15 minutes
    @Scheduled(cron = "0 */15 * * * *")
    public void poll() { }
}

Enable it with @EnableScheduling on a configuration class.

Quartz Scheduler

JobDetail job = JobBuilder.newJob(ReportJob.class).build();

Trigger trigger = TriggerBuilder.newTrigger()
    .withSchedule(CronScheduleBuilder
        .cronSchedule("0 0 9 ? * MON-FRI")   // note the ?
        .inTimeZone(TimeZone.getTimeZone("UTC")))
    .build();

scheduler.scheduleJob(job, trigger);

ScheduledExecutorService (fixed intervals)

For simple fixed-rate work with no cron semantics, the JDK has you covered:

ScheduledExecutorService ex = Executors.newScheduledThreadPool(1);
ex.scheduleAtFixedRate(this::poll, 0, 15, TimeUnit.MINUTES);