Appends an instant using ISO-8601 to the formatter with control over
the number of fractional digits.
!(p)
Instants have a fixed output format, although this method provides some
control over the fractional digits. They are converted to a date-time
with a zone-offset of UTC and printed using the standard ISO-8601 format.
The localized decimal style is not used.
!(p)
The {@code fractionalDigits} parameter allows the output of the fractional
second to be controlled. Specifying zero will cause no fractional digits
to be output. From 1 to 9 will output an increasing number of digits, using
zero right-padding if necessary. The special value -1 is used to output as
many digits as necessary to avoid any trailing zeroes.
!(p)
When parsing _in strict mode, the number of parsed digits must match the
fractional digits. When parsing _in lenient mode, any number of fractional
digits from zero to nine are accepted.
!(p)
The instant is obtained using {@link ChronoField#INSTANT_SECONDS INSTANT_SECONDS}
and optionally {@code NANO_OF_SECOND}. The value of {@code INSTANT_SECONDS}
may be outside the maximum range of {@code LocalDateTime}.
!(p)
The {@linkplain ResolverStyle resolver style} has no effect on instant parsing.
The end-of-day time of '24:00' is handled as midnight at the start of the following day.
The leap-second time of '23:59:60' is handled to some degree, see
{@link DateTimeFormatter#parsedLeapSecond()} for full details.
!(p)
An alternative to this method is to format/parse the instant as a single
epoch-seconds value. That is achieved using {@code appendValue(INSTANT_SECONDS)}.
@param fractionalDigits the number of fractional second digits to format with,
from 0 to 9, or -1 to use as many digits as necessary
@return this, for chaining, not null
@throws IllegalArgumentException if the number of fractional digits is invalid
Appends an instant using ISO-8601 to the formatter with control over the number of fractional digits. !(p) Instants have a fixed output format, although this method provides some control over the fractional digits. They are converted to a date-time with a zone-offset of UTC and printed using the standard ISO-8601 format. The localized decimal style is not used. !(p) The {@code fractionalDigits} parameter allows the output of the fractional second to be controlled. Specifying zero will cause no fractional digits to be output. From 1 to 9 will output an increasing number of digits, using zero right-padding if necessary. The special value -1 is used to output as many digits as necessary to avoid any trailing zeroes. !(p) When parsing _in strict mode, the number of parsed digits must match the fractional digits. When parsing _in lenient mode, any number of fractional digits from zero to nine are accepted. !(p) The instant is obtained using {@link ChronoField#INSTANT_SECONDS INSTANT_SECONDS} and optionally {@code NANO_OF_SECOND}. The value of {@code INSTANT_SECONDS} may be outside the maximum range of {@code LocalDateTime}. !(p) The {@linkplain ResolverStyle resolver style} has no effect on instant parsing. The end-of-day time of '24:00' is handled as midnight at the start of the following day. The leap-second time of '23:59:60' is handled to some degree, see {@link DateTimeFormatter#parsedLeapSecond()} for full details. !(p) An alternative to this method is to format/parse the instant as a single epoch-seconds value. That is achieved using {@code appendValue(INSTANT_SECONDS)}.
@param fractionalDigits the number of fractional second digits to format with, from 0 to 9, or -1 to use as many digits as necessary @return this, for chaining, not null @throws IllegalArgumentException if the number of fractional digits is invalid