Java Long primitive type maximum limit

Question

I am using the Long primitive type which increments by 1 whenever my 'generateNumber'method called. What happens if Long reaches to his maximum limit? will throw any exception or will reset to minimum value? here is my sample code:

class LongTest {
   private static long increment;
   public static long generateNumber(){
       ++increment;
       return increment;
   }
}

Pretty big range - `8 bytes signed (two's complement). Ranges from -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807.` http://www.cafeaulait.org/course/week2/02.html — Caffeinated, Mar 19 '13 at 16:48
Once you reached to max value, next it will get rollover to min value. — Smit, Mar 19 '13 at 16:49

score 424 · Accepted Answer · edited Dec 23 '15 at 15:53

424

Long.MAX_VALUE is 9,223,372,036,854,775,807.

If you were executing your function once per nanosecond, it would still take over 292 years to encounter this situation according to this source.

When that happens, it'll just wrap around to Long.MIN_VALUE, or -9,223,372,036,854,775,808 as others have said.

edited Dec 23 '15 at 15:53

daiscog

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answered Mar 19 '13 at 16:53

Krease

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That's a hell of a source. – Preston Aug 30 '13 at 02:57
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Least there's a good chance that source won't expire. – Oliver Dixon May 25 '15 at 15:17
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I like the source!! – fareed May 30 '16 at 07:17
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292 Million* years – argh1969 Dec 14 '16 at 04:54
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@argh1969 - what's your source? That would be true at once per __milli__second... – Krease Dec 14 '16 at 05:41
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And your code will be stopped through an active brain interface before 292 years have passed, no matter where you deploy it. – Ben May 15 '17 at 09:05
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[independend source](http://www.wolframalpha.com/input/?i=9,223,372,036,854,775,807+nanoseconds+in+years) ;-) – DerMike Jul 25 '17 at 12:50
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9223372036854775807 without commas for people like me who want to copy the number – matthew.kempson Apr 23 '18 at 16:00
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@matthew.kempson - I hope nobody ever needs to refer to the raw number in code! The static constant exists so nobody needs to refer to it like that. – Krease Apr 23 '18 at 17:49
and I was reading a long x long cinemaRoom sometime ago, imagine that – Mauricio Rodriguez Jun 06 '21 at 04:35

score 47 · Answer 2 · answered Mar 19 '13 at 16:47

47

It will overflow and wrap around to Long.MIN_VALUE.

Its not too likely though. Even if you increment 1,000,000 times per second it will take about 300,000 years to overflow.

answered Mar 19 '13 at 16:47

Zutty

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score 10 · Answer 3 · answered Mar 19 '13 at 16:47

10

Ranges from -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807.

It will start from -9,223,372,036,854,775,808

Long.MIN_VALUE.

answered Mar 19 '13 at 16:47

Ajay S

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score 10 · Answer 4 · edited May 23 '17 at 10:31

10

Exceding the maximum value of a long doesnt throw an exception, instead it cicles back. If you do this:

Long.MAX_VALUE + 1

you will notice that the result is the equivalent to Long.MIN_VALUE.

From here: java number exceeds long.max_value - how to detect?

edited May 23 '17 at 10:31

Community

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answered Mar 19 '13 at 16:48

jsedano

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Java Long primitive type maximum limit

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