This looks like a bug from the description below, although it is surprising
that it isn't caught by tests.
Stephen
On Wed, 3 May 2023, 21:47 SHARPE, Stuart (Commercial & Institutional CDIO),
<stuart.sha...@natwestmarkets.com> wrote:
> Hi Roger,
>
> Thanks for the reply.
>
> I must admit I am struggling to understand your explanation. I can't see
> how the choice of internal representation would affect the result in this
> way. I also don't see anything in the JavaDoc that describes values being
> truncated prior to the calculation, and even if it did, the results are not
> consistent - if that was the expected behaviour, the results from my
> previous example would have been 1000 and 1001, would they not?
>
> The part I quoted from the JavaDoc seems quite clear: it should return the
> number of whole units (millis in this case) between the two temporals. The
> number of milliseconds between 10:00:00.000999 and 10:00:01.000 is 999.001,
> which is 999 whole units.
>
> I think the below illustration makes it clearer that there is something
> wrong. The output values are all what I would expect as per the JavaDoc
> apart from the result for t2 = 10:00:01.000.
>
> var t1 = Instant.parse("2023-05-03T10:00:00.000999Z");
> var t2 = Instant.parse("2023-05-03T10:00:00.995Z");
>
> for(int i=0; i<10; i++) {
> System.out.println(ChronoUnit.MILLIS.between(t1, t2));
> t2 = t2.plusMillis(1);
> }
>
> This prints:
>
> 994
> 995
> 996
> 997
> 998
> 1000
> 1000
> 1001
> 1002
> 1003
>
> I'm fully prepared to accept that I've missed something, but at the moment
> I can't understand what that is.
>
> Regards,
>
> Stuart
>
>
> From: core-libs-dev <core-libs-dev-r...@openjdk.org> On Behalf Of Roger
> Riggs
> Sent: 03 May 2023 20:58
> To: core-libs-dev@openjdk.org
> Subject: Re: Time difference calculation bug
>
>
> Hi,
>
> The seconds and nano-seconds are computed separately.
> The representation of Instant holds seconds and nanoseconds separately.
>
> The computation is performed on the nano-seconds of the Instant and
> truncated to milliseconds.
> The value of 0.000999 becomes 0 when truncated to MILLIS.
>
> Regards, Roger
> On 5/3/23 12:54 PM, SHARPE, Stuart (Commercial & Institutional CDIO) wrote:
> Hello,
>
> I believe I have discovered a bug in java.time. I've searched Jira and
> couldn't find any existing similar issue.
>
> Consider the following code:
>
> var t1 = Instant.parse("2023-05-03T10:00:00.000999Z");
> var t2 = Instant.parse("2023-05-03T10:00:01.000Z");
> var t3 = Instant.parse("2023-05-03T10:00:01.001Z");
>
> System.out.println(MILLIS.between(t1, t2));
> System.out.println(MILLIS.between(t1, t3));
>
> This prints:
>
> 1000
> 1000
>
> Given that t3 is exactly one millisecond later than t2, it does not seem
> reasonable that they can both be 1000 milliseconds later than t1.
>
> The JavaDoc for between() states "The calculation returns a whole number,
> representing the number of complete units between the two temporals."
>
> Assuming I have understood this correctly, I think MILLIS.between(t1, t3)
> is correct but MILLIS.between(t1, t2) should return 999.
>
> Regards
>
> Stuart Sharpe
>
>
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