Calculate Elapsed Time in Java/Groovy

Groovy - Calculate if certain minutes are elapsed from the current time

isn't it way too complicated?

final long TWO_HOURS_MILIS = 2 * 60 * 60 * 1000l

Date downTimeStartCFDate = (Date)issue.getCustomFieldValue(downTimeStart)
Date downTimeEndCFDate = (Date)issue.getCustomFieldValue(downTimeEnd)
long now = System.currentTimeMillis()
long delta = now - downTimeStartCFDate.time

// fire between 1:59 and 2:00
if( delta % TWO_HOURS_MILIS >= TWO_HOURS_MILLIS - 60000 && now < downTimeEndCFDate.time ){
  sendEmail()
}

Checking elapsed time in Groovy/Grails

You can put the value in the session and it will persist between requests. For example:

def connected = {
    session.startTime = new Date().getTime()
}
def callEnded = {
    def endTime = new Date().getTime()
    timeHandler(endTime, session.startTime)
}
def timeHandler = {end, start->
    return end - start
}

How to calculate elasped time in Java from a provided hour ONLY

Firstly, I'd suggest using the Joda Time API. It's the best date/time API available for Java, in my opinion.

Next you need to work out exactly what to do in various corner cases. In particular, suppose the user enters "1" and you're near a daylight saving transition. It's possible that 1am happened twice (if the the time went 1:58, 1:59, 1:00, 1:01 because of a transition back away from DST) or that it didn't happen at all (if the time went 12:58, 12:59, 2:00 because of a transition forward into DST). You need to work out what to do in each of those situations - and bear in mind that this means knowing the time zone too.

Once you've worked that out, it may not be too hard. With Joda Time you can use withHourOfDay method to get from one time to another having set one component of the time - and likewise there are simple APIs for adding or subtracting a day, if you need to. You can then work out the time between two DateTime values very easily - again, Joda Time provides everything you need.

Here's an example which doesn't try to do anything with DST transitions, but it's a good starting point:

import org.joda.time.*;

public class Test
{
    public static void main(String[] args)
    {
        // Defaults to current time and time zone
        DateTime now = new DateTime();
        int hour = Integer.parseInt(args[0]);

        DateTime then = now
            .withHourOfDay(hour)
            .withMinuteOfHour(0)
            .withSecondOfMinute(0);
        if (then.isAfter(now))
        {
            then = then.minusDays(1);
        }
        Period period = new Period(then, now, PeriodType.seconds());

        System.out.println("Difference in seconds: " + period.getSeconds());
    }
}

Duration between two dates in Groovy

TimeCategory has some methods for getting a duration. You could use it like

use(groovy.time.TimeCategory) {
    def duration = date1 - date2
    print "Days: ${duration.days}, Hours: ${duration.hours}, etc."
}

Is there a Java library for calculating elapsed time?

Use Joda time's Period & PeriodFormatter. Example.

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