When will the java date collapse?

Question

AFAIK java stores dates in long variables as milliseconds. Consequently someday there will be no value (cause long has a maximum) which will correspond to the time of that instant. Do you know when it will happen?

I believe the sun is expected to go nova before then. Sun has already gone nova. — Paul Tomblin, Nov 16 '10 at 14:23
Actually, I have that wrong - Java Date has 292 million years, but according to http://www.space.com/scienceastronomy/solarsystem/death_of_earth_000224.html the earth has 500 million years. — Paul Tomblin, Nov 16 '10 at 14:30
Related: http://stackoverflow.com/questions/2978452/when-will-system-currenttimemillis-overflow — BalusC, Nov 16 '10 at 23:35

score 61 · Accepted Answer · answered Nov 16 '10 at 14:19

61

It's easy enough to find out:

public class Test {
    public static void main(String[] args) {
        System.out.println(new java.util.Date(Long.MAX_VALUE));
    }
}

Gives output (on my box):

Sun Aug 17 07:12:55 GMT 292278994

You may need to subtract a bit from Long.MAX_VALUE to cope with your time zone overflowing the range of long, but it will give a reasonable ballpark :)

answered Nov 16 '10 at 14:19

Jon Skeet

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I like it too :-) It even gives the second it will break ;) – aioobe Nov 16 '10 at 14:38
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No, no, no... it breaks one millisecond AFTER the time posted. If it was displaying milliseconds, that is. – Powerlord Nov 16 '10 at 16:23

score 28 · Answer 2 · edited May 23 '17 at 12:18

28

According to the current leap-year regulations the average number of days per year will be

365 + 1/4 − 1/100 + 1/400 = 365.2425 days per year

This means that we, in average, have 31556952000 milliseconds per year.

The long-value represents the number of milliseconds since the Epoch (1st of January, 1970) and the maximum number represented by a Java long is 2⁶³ − 1, so the following calculation

1970 + (2⁶³ − 1) / 31556952000

reveals that this representation will overflow year 292278994.

This can, as Jon Skeet points out, be confirmed by

-> System.out.println(new Date(Long.MAX_VALUE));
Sun Aug 17 08:12:55 CET 292278994

edited May 23 '17 at 12:18

Community

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answered Nov 16 '10 at 14:19

aioobe

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With such large numbers being used as dates, leap seconds and tidal acceleration probably need to be factored in too. – Qwerky Nov 16 '10 at 14:35
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@Qwerky, yeah, I thought about that too, and search for astronomical measurements of the number of milliseconds of a year, but then it struck me that the question was about the java date-implementation, and this does most likely *not* take tidal acceleration etc into account :-) – aioobe Nov 16 '10 at 14:37

When will the java date collapse?

2 Answers2

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