Scheduling Tasks in Spring with @Scheduled

@Component
public class Cleanup {

  @Scheduled(fixedRate = 5, timeUnit = TimeUnit.MINUTES)
  public void removeExpiredSessions() {
    // runs every 5 minutes, from startup on
  }
}

//Since.java
package com.javabrahman.scheduling;

import java.util.concurrent.atomic.AtomicLong;
import org.springframework.stereotype.Component;

@Component
public class Since {
  private final AtomicLong start = new AtomicLong();

  public String now() {
    long time = System.nanoTime();
    start.compareAndSet(0, time);   // the first call sets time zero
    long tenths = Math.round((time - start.get()) / 100_000_000.0);
    return String.format("%4.1f s", tenths / 10.0);
  }
}

//RateAndDelayTasks.java
package com.javabrahman.scheduling;

import org.springframework.context.annotation.Profile;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

public class RateAndDelayTasks {

  @Component
  @Profile("rate")
  public static class RateTask {
    private final Since since;

    public RateTask(Since since) {
      this.since = since;
    }

    @Scheduled(fixedRate = 500)
    public void run() throws InterruptedException {
      System.out.println(since.now() + "  fixedRate task starts");
      Thread.sleep(300);
    }
  }

  @Component
  @Profile("delay")
  public static class DelayTask {
    private final Since since;

    public DelayTask(Since since) {
      this.since = since;
    }

    @Scheduled(fixedDelay = 500)
    public void run() throws InterruptedException {
      System.out.println(since.now() + "  fixedDelay task starts");
      Thread.sleep(300);
    }
  }
}

//SchedulingApp.java
package com.javabrahman.scheduling;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.scheduling.annotation.EnableScheduling;

@SpringBootApplication
@EnableScheduling
public class SchedulingApp {

  // runs the application for the given number of milliseconds (default 1800), then closes it
  public static void main(String[] args) throws InterruptedException {
    long runFor = Long.getLong("runFor", 1800);
    try (ConfigurableApplicationContext context = SpringApplication.run(SchedulingApp.class, args)) {
      Thread.sleep(runFor);
    }
  }
}

//BusyTasks.java
package com.javabrahman.scheduling;

import org.springframework.context.annotation.Profile;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
@Profile("busy")
public class BusyTasks {
  private final Since since;

  public BusyTasks(Since since) {
    this.since = since;
  }

  @Scheduled(fixedRate = 250)
  public void heartbeat() {
    Thread thread = Thread.currentThread();
    System.out.println(since.now() + "  heartbeat on " + thread.getName() + (thread.isVirtual() ? " (virtual)" : ""));
  }

  @Scheduled(initialDelay = 300, fixedDelay = 60_000)
  public void report() throws InterruptedException {
    System.out.println(since.now() + "  report starts on " + Thread.currentThread().getName());
    Thread.sleep(1000);
    System.out.println(since.now() + "  report ends");
  }
}

//CronCheck.java
package com.javabrahman.scheduling;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import org.springframework.scheduling.support.CronExpression;

public class CronCheck {
  static final DateTimeFormatter FORMAT = DateTimeFormatter.ofPattern("EEE dd MMM yyyy HH:mm:ss");

  public static void main(String[] args) {
    LocalDateTime from = LocalDateTime.of(2026, 11, 7, 22, 40);
    show(from, "0 15 9 * * MON-FRI", "9:15 on weekdays");
    show(from, "0 */20 * * * *", "every 20 minutes");
    show(from, "0 0 2 * * *", "every night at 2:00");
    show(from, "0 0 18 L * *", "18:00 on the last day of the month");
    show(from, "0 0 10 * * MON#1", "10:00 on the first Monday of the month");
    show(from, "0 0 9 1W * *", "9:00 on the weekday nearest to the 1st");
    show(from, "@daily", "macro: midnight every day");
    try {
      CronExpression.parse("0 15 9 * MON-FRI");   // five fields, crontab style
    } catch (IllegalArgumentException e) {
      System.out.println("\"0 15 9 * MON-FRI\": " + e.getMessage());
    }
  }

  static void show(LocalDateTime from, String expression, String meaning) {
    CronExpression cron = CronExpression.parse(expression);
    System.out.printf("%-20s %s%n", expression, meaning);
    LocalDateTime next = from;
    for (int i = 0; i < 3; i++) {
      next = cron.next(next);
      System.out.println("                     " + FORMAT.format(next));
    }
  }
}

@Scheduled(cron = "${reports.daily-cron:0 0 7 * * *}", zone = "Asia/Kolkata")
public void sendDailyReport() {
  // 7:00 India time by default; reports.daily-cron=- in a profile switches it off
}

//FailingTask.java
package com.javabrahman.scheduling;

import org.springframework.context.annotation.Profile;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
@Profile("failing")
public class FailingTask {
  private final Since since;
  private int runs;

  public FailingTask(Since since) {
    this.since = since;
  }

  @Scheduled(fixedRate = 400)
  public void importFeed() {
    runs++;
    System.out.println(since.now() + "  import run " + runs);
    if (runs == 2) {
      throw new IllegalStateException("feed server not reachable");
    }
  }
}

logging.pattern.console=%m%n%ex{1}