java-tutorials/intelliJ/remote-debugging/README.adoc

:toc:
:spring_version: current
:icons: font
:source-highlighter: prettify
:project_id: gs-scheduling-tasks
This guide walks you through the steps for scheduling tasks with Spring.

== What you'll build

You'll build an application that prints out the current time every five seconds using Spring's `@Scheduled` annotation.

== What you'll need

:java_version: 1.8
include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/prereq_editor_jdk_buildtools.adoc[]


include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/how_to_complete_this_guide.adoc[]


include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/hide-show-gradle.adoc[]

include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/hide-show-maven.adoc[]

include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/hide-show-sts.adoc[]



[[initial]]
== Create a scheduled task
Now that you've set up your project, you can create a scheduled task.

`src/main/java/hello/ScheduledTasks.java`
[source,java]
----
include::complete/src/main/java/hello/ScheduledTasks.java[]
----

The `Scheduled` annotation defines when a particular method runs.
NOTE: This example uses `fixedRate`, which specifies the interval between method invocations measured from the start time of each invocation. There are https://docs.spring.io/spring/docs/{spring_version}/spring-framework-reference/html/scheduling.html#scheduling-annotation-support-scheduled[other options], like `fixedDelay`, which specifies the interval between invocations measured from the completion of the task. You can also https://docs.spring.io/spring/docs/{spring_version}/javadoc-api/org/springframework/scheduling/support/CronSequenceGenerator.html[use `@Scheduled(cron=". . .")` expressions for more sophisticated task scheduling].

== Enable Scheduling

Although scheduled tasks can be embedded in web apps and WAR files, the simpler approach demonstrated below creates a standalone application. You package everything in a single, executable JAR file, driven by a good old Java `main()` method.

`src/main/java/hello/Application.java`
[source,java]
----
include::complete/src/main/java/hello/Application.java[]
----

include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/spring-boot-application.adoc[]

https://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#scheduling-enable-annotation-support[`@EnableScheduling`] ensures that a background task executor is created. Without it, nothing gets scheduled.


include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/build_an_executable_jar_subhead.adoc[]

include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/build_an_executable_jar_with_both.adoc[]



Logging output is displayed and you can see from the logs that it is on a background thread. You should see your scheduled task fire every 5 seconds:

....
[...]
2016-08-25 13:10:00.143  INFO 31565 --- [pool-1-thread-1] hello.ScheduledTasks : The time is now 13:10:00
2016-08-25 13:10:05.143  INFO 31565 --- [pool-1-thread-1] hello.ScheduledTasks : The time is now 13:10:05
2016-08-25 13:10:10.143  INFO 31565 --- [pool-1-thread-1] hello.ScheduledTasks : The time is now 13:10:10
2016-08-25 13:10:15.143  INFO 31565 --- [pool-1-thread-1] hello.ScheduledTasks : The time is now 13:10:15
....

== Summary

Congratulations! You created an application with a scheduled task. Heck, the actual code was shorter than the build file! This technique works in any type of application.

== See Also

The following guides may also be helpful:

* https://spring.io/guides/gs/spring-boot/[Building an Application with Spring Boot]
* https://spring.io/guides/gs/batch-processing/[Creating a Batch Service]

include::https://raw.githubusercontent.com/spring-guides/getting-started-macros/master/footer.adoc[]