How to Schedule a Periodic Task in Java?

How to Schedule a Periodic Task in Java?

I need to schedule a task to run in at fixed interval of time. How can I do this with support of long intervals (for example on each 8 hours)?

I'm currently using java.util.Timer.scheduleAtFixedRate. Does java.util.Timer.scheduleAtFixedRate support long time intervals?

12 Answers

Use a ScheduledExecutorService:

 private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
 scheduler.scheduleAtFixedRate(yourRunnable, 8, 8, TimeUnit.HOURS);
1

You should take a look to Quartz it's a java framework wich works with EE and SE editions and allows to define jobs to execute an specific time

Try this way ->

Firstly create a class TimeTask that run your task, it looks like:

public class CustomTask extends TimerTask  {

   public CustomTask(){

     //Constructor

   }

   public void run() {
       try {

         // Your task process

       } catch (Exception ex) {
           System.out.println("error running thread " + ex.getMessage());
       }
    }
}

then in main class you instantiate the task and run it periodically started by a specified date:

 public void runTask() {

        Calendar calendar = Calendar.getInstance();
        calendar.set(
           Calendar.DAY_OF_WEEK,
           Calendar.MONDAY
        );
        calendar.set(Calendar.HOUR_OF_DAY, 15);
        calendar.set(Calendar.MINUTE, 40);
        calendar.set(Calendar.SECOND, 0);
        calendar.set(Calendar.MILLISECOND, 0);



        Timer time = new Timer(); // Instantiate Timer Object

        // Start running the task on Monday at 15:40:00, period is set to 8 hours
        // if you want to run the task immediately, set the 2nd parameter to 0
        time.schedule(new CustomTask(), calendar.getTime(), TimeUnit.HOURS.toMillis(8));
}
2

Use Google Guava AbstractScheduledService as given below:

public class ScheduledExecutor extends AbstractScheduledService {

   @Override
   protected void runOneIteration() throws Exception {
      System.out.println("Executing....");
   }

   @Override
   protected Scheduler scheduler() {
        return Scheduler.newFixedRateSchedule(0, 3, TimeUnit.SECONDS);
   }

   @Override
   protected void startUp() {
       System.out.println("StartUp Activity....");
   }


   @Override
   protected void shutDown() {
       System.out.println("Shutdown Activity...");
   }

   public static void main(String[] args) throws InterruptedException {
       ScheduledExecutor se = new ScheduledExecutor();
       se.startAsync();
       Thread.sleep(15000);
       se.stopAsync();
   }
}

If you have more services like this, then registering all services in ServiceManager will be good as all services can be started and stopped together. Read here for more on ServiceManager.

0

If you want to stick with java.util.Timer, you can use it to schedule at large time intervals. You simply pass in the period you are shooting for. Check the documentation here.

0

Do something every one second

Timer timer = new Timer();
timer.schedule(new TimerTask() {
    @Override
    public void run() {
        //code
    }
}, 0, 1000);
1

These two classes can work together to schedule a periodic task:

Scheduled Task

import java.util.TimerTask;
import java.util.Date;

// Create a class extending TimerTask
public class ScheduledTask extends TimerTask {
    Date now; 
    public void run() {
        // Write code here that you want to execute periodically.
        now = new Date();                      // initialize date
        System.out.println("Time is :" + now); // Display current time
    }
}
Elena Rostova
Author

Elena Rostova

Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.