How can I calculate the age in Java

Question

I have an Problem with calculating an Age..

public long getAlter() {

    Date now = new Date();
    long yearInMillis = 365 * 24 * 60 * 60  * 1000;
    long alter =   (now.getTime() - buildYear.getTime()) /365/24/60/60/1000 ;

    return alter;
}

The buildYear is given: Year 22.05.2007.

--> (dd.mm.yyyy)

I need a function to calculate the Year (not the Month or so), in this example here: 7 Years.
I need a function to calculate the Days, in this example 2576 Days.

How can I define this?

Like this: http://www.topster.de/kalender/zeitrechner.php?styp=zeit&sdatum=22.05.2007&szeit=12%3A00%3A00&edatum=&ezeit=12%3A00%3A00&typ=jetzt&subDazu=%2B&jahredazu=0&tagedazu=0&zeitdazu=00%3A00%3A00

(already choosen)

@ALL: It's not an duplicate, because I will not work with Joda!

You're going to get a whole lot of rounding errors with `/365/24/60/60/1000` — awksp, Jun 10 '14 at 14:12
@user3714925 Duplicate doesn't suggest only Joda. You can also use classes added in Java 8 or `Calendar` as shown in different answers in that question. BTW you are having problem with integer overflow in `365 * 24 * 60 * 60 * 1000`. To solve it use `long` as first argument of multiplying so rest of arguments will also be long like `365L * 24 * 60 * 60 * 1000`. Also you didn't specify if mechanism should include also time (hours, minutes). This detail is important since there will be no full day between `1.1.2001 12:00` and `2.1.2001 11:59` because you will lack one second. — Pshemo, Jun 10 '14 at 14:24

score 3 · Answer 1 · edited May 23 '17 at 12:20

3

This link seems to have done something similar:

How do I calculate someone's age in Java?

In case the link ever breaks, here is what is said:

Check out Joda, which simplifies date/time calculations (Joda is also the basis of the new standard Java date/time apis, so you'll be learning a soon-to-be-standard API).

EDIT: Java 8 will have something very similar and will be worth checking out.

e.g.
LocalDate birthdate = new LocalDate (1970, 1, 20);
LocalDate now = new LocalDate();
Years age = Years.yearsBetween(birthdate, now);
which is as simple as you could want. The current Java stuff is (as you've identified) somewhat unintuitive.

edited May 23 '17 at 12:20

Community

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answered Jun 10 '14 at 14:07

krodmannix

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You mean the link within SO ? – Brian Agnew Jun 10 '14 at 14:08
@BrianAgnew yes - I doubt it will ever be broken, but in the rare case the question or answer is deleted. – krodmannix Jun 10 '14 at 14:16
@user3714925 - Why won't you use Joda ? – Brian Agnew Jun 10 '14 at 15:15

How can I calculate the age in Java

1 Answers1