Need to compare date time in GMT

[Sankar Ramakrishnan]

Hi,
I need to run a thread every 4 hours from GMT. This application can run from any Time zone (thats why GMT is preferred.) When the application starts i can do the processing and i need to set the sleep value of the thread. i am not able to to calculate the remaining milliseconds from the current time to the next scheduled time in GMT so that i can make set the thread to sleep for that particulcar period of time. Please help.


Thanks,
Sankar

[Phil Johnston]

Not sure if it's what you're after but:

package com;

import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import java.util.Timer;
import java.util.TimerTask;

/**
* Created by IntelliJ IDEA.
* User: Phil Johnston
* Date: 09-Aug-2005
* Time: 20:22:37
*/
public class TestTimer
{
private static TimeZone GMT = TimeZone.getTimeZone("GMT");
private static int DELAY = 1000*60*60*4;

public static void main(String[] args)
{
Timer t = new Timer();
TimerTask task = new LocalTimerTask();

Calendar midnight = GregorianCalendar.getInstance(GMT);
midnight.set(2005, 8, 10, 0, 0, 0);

t.scheduleAtFixedRate(task, midnight.getTime(), DELAY);

}

private static class LocalTimerTask extends TimerTask
{
public void run()
{
// do my stuff
}
}
}

[Sankar Ramakrishnan]

Thanks dude,
One small issue is it gets executed for the elapsed time.

I need to schedule every 4 hrs from GMT. but it should not execute for elapsed values.

i.e If i start the exe at 9 AM GMT, it should run next time at 12 PM GMT, not 2 times for 4 AM and 8 AM GMT.

Hope i am clear.

Regards,
Sankar

[Sankar Ramakrishnan]

This is the method i wrote to get the no of milliseconds remaining to reach the next scheduled task.

private long getSleepInterval(int repeatHours)
{
Calendar cal = new GregorianCalendar();
cal.setTimeZone(TimeZone.getTimeZone("GMT"));

Calendar newCal = new GregorianCalendar(TimeZone.getTimeZone("GMT"));
newCal.set(cal.get(Calendar.YEAR),cal.get(Calendar.MONTH),cal.get(Calendar.DATE),0,0,0);

int maxLength = 24/repeatHours + 1;

long[] timeinMilliSeconds = new long[maxLength];

long timeinMillis = cal.getTime().getTime();

timeinMilliSeconds[0] = newCal.getTime().getTime();

if(timeinMilliSeconds[0] > timeinMillis)
return (timeinMilliSeconds[0] - timeinMillis);


for (int i = 1;i < maxLength ;i++ )
{
newCal.add(Calendar.HOUR_OF_DAY,repeatHours);
timeinMilliSeconds[i] = newCal.getTime().getTime();
if(timeinMilliSeconds[i] > timeinMillis)
return (timeinMilliSeconds[i] - timeinMillis);


}
return 0;

}