Use a ScheduledExecutorService:
private final ScheduledExecutorService scheduler = Executors.newScheduledThreadPool(1);
scheduler.scheduleAtFixedRate(yourRunnable, 8, 8, TimeUnit.HOURS);
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));
}
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.
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.
I use Spring Framework's feature. (spring-context jar or maven dependency).
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
@Component
public class ScheduledTaskRunner {
@Autowired
@Qualifier("TempFilesCleanerExecution")
private ScheduledTask tempDataCleanerExecution;
@Scheduled(fixedDelay = TempFilesCleanerExecution.INTERVAL_TO_RUN_TMP_CLEAN_MS /* 1000 */)
public void performCleanTempData() {
tempDataCleanerExecution.execute();
}
}
ScheduledTask is my own interface with my custom method execute, which I call as my scheduled task.
These two classes can work together to schedule a periodic 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
}
}
import java.util.Timer;
public class SchedulerMain {
public static void main(String args[]) throws InterruptedException {
Timer time = new Timer(); // Instantiate Timer Object
ScheduledTask st = new ScheduledTask(); // Instantiate SheduledTask class
time.schedule(st, 0, 1000); // Create task repeating every 1 sec
//for demo only.
for (int i = 0; i <= 5; i++) {
System.out.println("Execution in Main Thread...." + i);
Thread.sleep(2000);
if (i == 5) {
System.out.println("Application Terminates");
System.exit(0);
}
}
}
}
Reference https://www.mkyong.com/java/how-to-run-a-task-periodically-in-java/
Have you tried Spring Scheduler using annotations ?
@Scheduled(cron = "0 0 0/8 ? * * *")
public void scheduledMethodNoReturnValue(){
//body can be another method call which returns some value.
}
you can do this with xml as well.
<task:scheduled-tasks>
<task:scheduled ref = "reference" method = "methodName" cron = "<cron expression here> -or- ${<cron expression from property files>}"
<task:scheduled-tasks>
my servlet contains this as a code how to keep this in scheduler if a user presses accept
if(bt.equals("accept")) {
ScheduledExecutorService scheduler=Executors.newScheduledThreadPool(1);
String lat=request.getParameter("latlocation");
String lng=request.getParameter("lnglocation");
requestingclass.updatelocation(lat,lng);
}
