How to Use @Scheduled Annotation in Spring for Task Scheduling

Use the @Scheduled annotation on a method to run it automatically at fixed intervals or cron expressions. Enable scheduling by adding @EnableScheduling to a configuration class. The method annotated with @Scheduled should have no parameters and return void.

Syntax

The @Scheduled annotation can be used with different parameters to control when the method runs:

• fixedRate: Runs the method at a fixed interval in milliseconds.
• fixedDelay: Runs the method with a fixed delay after the previous execution finishes.
• cron: Runs the method based on a cron expression for flexible scheduling.

The method must be void and take no arguments.

java

@Scheduled(fixedRate = 5000)
public void task() {
    // code to run every 5 seconds
}

@Scheduled(fixedDelay = 10000)
public void taskWithDelay() {
    // code runs 10 seconds after last execution finishes
}

@Scheduled(cron = "0 0/1 * * * ?")
public void cronTask() {
    // code runs every minute
}

Example

This example shows a Spring Boot application that prints a message every 3 seconds using @Scheduled(fixedRate = 3000). Scheduling is enabled with @EnableScheduling.

java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@SpringBootApplication
@EnableScheduling
public class ScheduledExampleApplication {
    public static void main(String[] args) {
        SpringApplication.run(ScheduledExampleApplication.class, args);
    }
}

@Component
class ScheduledTasks {
    @Scheduled(fixedRate = 3000)
    public void printMessage() {
        System.out.println("Task executed at " + java.time.LocalTime.now());
    }
}

Output

Task executed at 10:00:00.123
Task executed at 10:00:03.124
Task executed at 10:00:06.125
... (every 3 seconds)

Common Pitfalls

• Forgetting to add @EnableScheduling in a configuration class disables all scheduled tasks.
• The scheduled method must be public, return void, and have no parameters.
• Using fixedRate runs tasks at a fixed interval regardless of task duration, which can cause overlap if the task takes longer than the interval.
• Using fixedDelay waits for the task to finish before starting the delay timer.
• Incorrect cron expressions can cause tasks not to run; always validate cron syntax.

java

@Component
class WrongScheduled {
    // Wrong: method has parameters
    @Scheduled(fixedRate = 1000)
    public void taskWithParam(String param) {
        System.out.println(param);
    }

    // Correct:
    @Scheduled(fixedRate = 1000)
    public void correctTask() {
        System.out.println("Runs every second");
    }
}

Quick Reference

Use this quick guide to remember key points about @Scheduled:

Parameter	Description	Example
fixedRate	Runs method every fixed milliseconds regardless of duration	@Scheduled(fixedRate = 5000)
fixedDelay	Runs method after fixed delay from last completion	@Scheduled(fixedDelay = 5000)
cron	Runs method based on cron expression	@Scheduled(cron = "0 0/5 * * * ?")
@EnableScheduling	Enable scheduling support in Spring	Add on a @Configuration or @SpringBootApplication class

Key Takeaways

Add @EnableScheduling to enable scheduled tasks in Spring.

Annotate a void, no-argument method with @Scheduled to run it automatically.

Use fixedRate for regular intervals and fixedDelay to wait after task completion.

Validate cron expressions carefully to avoid scheduling errors.

Scheduled methods must be public and have no parameters.