Calculate elapsed time in Java / Groovy

Question

I have...

Date start = new Date()

...
...
...

Date stop = new Date()

I'd like to get the years, months, days, hours, minutes and seconds ellapsed between these two dates.

--

I'll refine the question.

I just want to get the elapsed time, as an absolute measure, that is without taking into account leap years, the days of each month, etc.

Thus I think it's impossible to get the years and months elapsed, all I can get is days, hours, minutes and seconds.

More specifically I want to tell that a certain task lasted for e.g.

20 sec
13 min, 4 sec
2 h, 10 min, 2 sec
4 d, 4 h, 2 min, 2 sec

So please forgive my lack of precision.

Answer 1

Not so easy with the standard Date API.

You might want to look at Joda Time, or JSR-310 instead.

I'm not an expert in Joda, but I think the code would be:

Interval interval = new Interval(d1.getTime(), d2.getTime());
Period period = interval.toPeriod();
System.out.printf(
    "%d years, %d months, %d days, %d hours, %d minutes, %d seconds%n", 
    period.getYears(), period.getMonths(), period.getDays(),
    period.getHours(), period.getMinutes(), period.getSeconds());

Answer 2

Hmm, if I get what you're asking, you want to know that if:

start = Jan 1, 2001, 10:00:00.000 am and

stop = Jan 6, 2003, 12:01:00.000 pm

you want an answer of 2 years, 0 months, 5 days, 2 hours, 1 minute

Unfortunately, this is a specious answer. What if the dates were Jan 2, and Jan 31? Would that be 29 days? Ok, but Feb 2 to Mar 2 is 28 (29) days, but would be listed as 1 month?

The length of time in anything other than seconds or possibly days is variable without knowing the context since months and years are of different lengths. The difference between 2 dates should be in static units, which are easily computable from stop.getTime() - start.getTime() (which is the difference in millisecs)

Answer 3

You can do all of this with division and mod.

long l1 = start.getTime();
long l2 = stop.getTime();
long diff = l2 - l1;

long secondInMillis = 1000;
long minuteInMillis = secondInMillis * 60;
long hourInMillis = minuteInMillis * 60;
long dayInMillis = hourInMillis * 24;
long yearInMillis = dayInMillis * 365;

long elapsedYears = diff / yearInMillis;
diff = diff % yearInMillis;
long elapsedDays = diff / dayInMillis;
diff = diff % dayInMillis;
long elapsedHours = diff / hourInMillis;
diff = diff % hourInMillis;
long elapsedMinutes = diff / minuteInMillis;
diff = diff % minuteInMillis;
long elapsedSeconds = diff / secondInMillis;

That should give you all of the information you requested.

EDIT: Since people seem to be confused, no, this does not take things like leap years or daylight savings time switches into account. It is pure elapsed time, which is what opensas asked for.

Answer 4

Regarding JodaTime I just got it going; thanks to the responder who suggested it. Here's a more condensed version of the Joda code suggested:

Period period = new Period(d1.getTime(), d2.getTime());
System.out.printf(
    "%d years, %d months, %d days, %d hours, %d minutes, %d seconds%n", 
    period.getYears(), period.getMonths(), period.getDays(),
    period.getHours(), period.getMinutes(), period.getSeconds());

(not sure if this is helping the original question but certainly searchers).

Answer 5

There is no point creating a Date object as all this does is wrap System.currentTimeMillis(). The getTime() function just unwraps the Date object. I suggest you just use this function to obtain a long.

If you only need second accuracy, this is fine. However if you want sub-millisecond accuracy use System.nanoTime() to get the elapse time.

Answer 6

Apart from the aforementioned great JodaTime API which I do recommend, the best standard Java alternative you can have is the java.util.Calendar. It is cumbersome to work with it (this is an understatement .. look at the single-line JodaTime examples here), but you can calculate the elapsed time with it as well. Important key is that you should use the Calendar#add() in a loop to get the elapsed value for years, months and days to take leap days, years and centuries into account. You should not calculate them back from the (milli)seconds.

Here's a basic example:

import java.util.Calendar;

public class Test {

    public static void main(String[] args) throws Exception {
        Calendar start = Calendar.getInstance();
        start.set(1978, 2, 26, 12, 35, 0); // Just an example.
        Calendar end = Calendar.getInstance();

        Integer[] elapsed = new Integer[6];
        Calendar clone = (Calendar) start.clone(); // Otherwise changes are been reflected.
        elapsed[0] = elapsed(clone, end, Calendar.YEAR);
        clone.add(Calendar.YEAR, elapsed[0]);
        elapsed[1] = elapsed(clone, end, Calendar.MONTH);
        clone.add(Calendar.MONTH, elapsed[1]);
        elapsed[2] = elapsed(clone, end, Calendar.DATE);
        clone.add(Calendar.DATE, elapsed[2]);
        elapsed[3] = (int) (end.getTimeInMillis() - clone.getTimeInMillis()) / 3600000;
        clone.add(Calendar.HOUR, elapsed[3]);
        elapsed[4] = (int) (end.getTimeInMillis() - clone.getTimeInMillis()) / 60000;
        clone.add(Calendar.MINUTE, elapsed[4]);
        elapsed[5] = (int) (end.getTimeInMillis() - clone.getTimeInMillis()) / 1000;

        System.out.format("%d years, %d months, %d days, %d hours, %d minutes, %d seconds", elapsed);
    }

    private static int elapsed(Calendar before, Calendar after, int field) {
        Calendar clone = (Calendar) before.clone(); // Otherwise changes are been reflected.
        int elapsed = -1;
        while (!clone.after(after)) {
            clone.add(field, 1);
            elapsed++;
        }
        return elapsed;
    }

}

It should print my age as of now =)

Oh, I should add, you can "convert" Date to Calendar using Calendar#setTime().

Answer 7

I've just discovered this quickly solution (in Groovy):

TimeDuration td = TimeCategory.minus( stop, start )
println td

Answer 8

Well since Java 1.5 you should use TimeUnit.

Here is a simple & plain example for this. I think in groovy it might get shorter(as always).

/**
 * Formats a given {@link Date} to display a since-then timespan.
 * @param created
 * @return String with a format like "3 minutes ago"
 */
public static String getElapsedTime(Date created) {
    long duration = System.currentTimeMillis() - created.getTime();
    long seconds = TimeUnit.MILLISECONDS.toSeconds(duration);
    long days = TimeUnit.MILLISECONDS.toDays(duration);
    long hours = TimeUnit.MILLISECONDS.toHours(duration);
    long minutes = TimeUnit.MILLISECONDS.toMinutes(duration);
    if (days > 0) {
        return days + " days";
    }
    if (hours > 0) {
        return hours + " hrs";
    }
    if (minutes > 0) {
        return minutes + " minutes";
    }

    return seconds + " seconds";
}

Oh and avoid multiple returns please ;)