How did the scheduler work according to the schedule?

A scheduler in Java is usually implemented using task schedulers such as ScheduledExecutorService or libraries like Quartz. It allows tasks to be executed at specific intervals or according to a schedule (cron expressions).

Working principle: the scheduler stores the task schedule and launches them at the appropriate time, creating separate threads or using a thread pool. Tasks can be one-time or recurring.

Example with ScheduledExecutorService:

ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);

Runnable task = () -> System.out.println("Executing scheduled task");

// Launch task with a delay of 10 seconds
scheduler.schedule(task, 10, TimeUnit.SECONDS);

// Launch task repeatedly every 5 seconds
scheduler.scheduleAtFixedRate(task, 0, 5, TimeUnit.SECONDS);

Thus, the scheduler ensures automatic task execution at the right time without manual control.