+ * This chronology defines the rules of the ISO calendar system. + * This calendar system is based on the ISO-8601 standard, which is the + * de facto world calendar. + *
+ * The fields are defined as follows: + *
+ * + *
+ * The ID uniquely identifies the {@code Chrono}. + * It can be used to lookup the {@code Chrono} using {@link #of(String)}. + * + * @return the chronology ID - 'ISO' + * @see #getCalendarType() + */ + @Override + public String getId() { + return "ISO"; + } + + /** + * Gets the calendar type of the underlying calendar system - 'iso8601'. + *
+ * The calendar type is an identifier defined by the
+ * Unicode Locale Data Markup Language (LDML) specification.
+ * It can be used to lookup the {@code Chrono} using {@link #of(String)}.
+ * It can also be used as part of a locale, accessible via
+ * {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
+ *
+ * @return the calendar system type - 'iso8601'
+ * @see #getId()
+ */
+ @Override
+ public String getCalendarType() {
+ return "iso8601";
+ }
+
+ //-----------------------------------------------------------------------
+ /**
+ * Obtains an ISO local date from the era, year-of-era, month-of-year
+ * and day-of-month fields.
+ *
+ * @param era the ISO era, not null
+ * @param yearOfEra the ISO year-of-era
+ * @param month the ISO month-of-year
+ * @param dayOfMonth the ISO day-of-month
+ * @return the ISO local date, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate date(Era
+ * This is equivalent to {@link LocalDate#of(int, int, int)}.
+ *
+ * @param prolepticYear the ISO proleptic-year
+ * @param month the ISO month-of-year
+ * @param dayOfMonth the ISO day-of-month
+ * @return the ISO local date, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate date(int prolepticYear, int month, int dayOfMonth) {
+ return LocalDate.of(prolepticYear, month, dayOfMonth);
+ }
+
+ /**
+ * Obtains an ISO local date from the era, year-of-era and day-of-year fields.
+ *
+ * @param era the ISO era, not null
+ * @param yearOfEra the ISO year-of-era
+ * @param dayOfYear the ISO day-of-year
+ * @return the ISO local date, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate dateYearDay(Era
+ * This is equivalent to {@link LocalDate#ofYearDay(int, int)}.
+ *
+ * @param prolepticYear the ISO proleptic-year
+ * @param dayOfYear the ISO day-of-year
+ * @return the ISO local date, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate dateYearDay(int prolepticYear, int dayOfYear) {
+ return LocalDate.ofYearDay(prolepticYear, dayOfYear);
+ }
+
+ //-----------------------------------------------------------------------
+ /**
+ * Obtains an ISO local date from another date-time object.
+ *
+ * This is equivalent to {@link LocalDate#from(TemporalAccessor)}.
+ *
+ * @param temporal the date-time object to convert, not null
+ * @return the ISO local date, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate date(TemporalAccessor temporal) {
+ return LocalDate.from(temporal);
+ }
+
+ /**
+ * Obtains an ISO local date-time from another date-time object.
+ *
+ * This is equivalent to {@link LocalDateTime#from(TemporalAccessor)}.
+ *
+ * @param temporal the date-time object to convert, not null
+ * @return the ISO local date-time, not null
+ * @throws DateTimeException if unable to create the date-time
+ */
+ @Override // override with covariant return type
+ public LocalDateTime localDateTime(TemporalAccessor temporal) {
+ return LocalDateTime.from(temporal);
+ }
+
+ /**
+ * Obtains an ISO zoned date-time from another date-time object.
+ *
+ * This is equivalent to {@link ZonedDateTime#from(TemporalAccessor)}.
+ *
+ * @param temporal the date-time object to convert, not null
+ * @return the ISO zoned date-time, not null
+ * @throws DateTimeException if unable to create the date-time
+ */
+ @Override // override with covariant return type
+ public ZonedDateTime zonedDateTime(TemporalAccessor temporal) {
+ return ZonedDateTime.from(temporal);
+ }
+
+ /**
+ * Obtains an ISO zoned date-time in this chronology from an {@code Instant}.
+ *
+ * This is equivalent to {@link ZonedDateTime#ofInstant(Instant, ZoneId)}.
+ *
+ * @param instant the instant to create the date-time from, not null
+ * @param zone the time-zone, not null
+ * @return the zoned date-time, not null
+ * @throws DateTimeException if the result exceeds the supported range
+ */
+ public ZonedDateTime zonedDateTime(Instant instant, ZoneId zone) {
+ return ZonedDateTime.ofInstant(instant, zone);
+ }
+
+ //-----------------------------------------------------------------------
+ /**
+ * Obtains the current ISO local date from the system clock in the default time-zone.
+ *
+ * This will query the {@link Clock#systemDefaultZone() system clock} in the default
+ * time-zone to obtain the current date.
+ *
+ * Using this method will prevent the ability to use an alternate clock for testing
+ * because the clock is hard-coded.
+ *
+ * @return the current ISO local date using the system clock and default time-zone, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate dateNow() {
+ return dateNow(Clock.systemDefaultZone());
+ }
+
+ /**
+ * Obtains the current ISO local date from the system clock in the specified time-zone.
+ *
+ * This will query the {@link Clock#system(ZoneId) system clock} to obtain the current date.
+ * Specifying the time-zone avoids dependence on the default time-zone.
+ *
+ * Using this method will prevent the ability to use an alternate clock for testing
+ * because the clock is hard-coded.
+ *
+ * @return the current ISO local date using the system clock, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate dateNow(ZoneId zone) {
+ return dateNow(Clock.system(zone));
+ }
+
+ /**
+ * Obtains the current ISO local date from the specified clock.
+ *
+ * This will query the specified clock to obtain the current date - today.
+ * Using this method allows the use of an alternate clock for testing.
+ * The alternate clock may be introduced using {@link Clock dependency injection}.
+ *
+ * @param clock the clock to use, not null
+ * @return the current ISO local date, not null
+ * @throws DateTimeException if unable to create the date
+ */
+ @Override // override with covariant return type
+ public LocalDate dateNow(Clock clock) {
+ Objects.requireNonNull(clock, "clock");
+ return date(LocalDate.now(clock));
+ }
+
+ //-----------------------------------------------------------------------
+ /**
+ * Checks if the year is a leap year, according to the ISO proleptic
+ * calendar system rules.
+ *
+ * This method applies the current rules for leap years across the whole time-line.
+ * In general, a year is a leap year if it is divisible by four without
+ * remainder. However, years divisible by 100, are not leap years, with
+ * the exception of years divisible by 400 which are.
+ *
+ * For example, 1904 is a leap year it is divisible by 4.
+ * 1900 was not a leap year as it is divisible by 100, however 2000 was a
+ * leap year as it is divisible by 400.
+ *
+ * The calculation is proleptic - applying the same rules into the far future and far past.
+ * This is historically inaccurate, but is correct for the ISO-8601 standard.
+ *
+ * @param prolepticYear the ISO proleptic year to check
+ * @return true if the year is leap, false otherwise
+ */
+ @Override
+ public boolean isLeapYear(long prolepticYear) {
+ return ((prolepticYear & 3) == 0) && ((prolepticYear % 100) != 0 || (prolepticYear % 400) == 0);
+ }
+
+ @Override
+ public int prolepticYear(Era