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IsoChronology

public final class IsoChronology
extends AbstractChronology implements Serializable

java.lang.Object
   ↳ java.time.chrono.AbstractChronology
     ↳ java.time.chrono.IsoChronology


The ISO calendar system.

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:

  • era - There are two eras, 'Current Era' (CE) and 'Before Current Era' (BCE).
  • year-of-era - The year-of-era is the same as the proleptic-year for the current CE era. For the BCE era before the ISO epoch the year increases from 1 upwards as time goes backwards.
  • proleptic-year - The proleptic year is the same as the year-of-era for the current era. For the previous era, years have zero, then negative values.
  • month-of-year - There are 12 months in an ISO year, numbered from 1 to 12.
  • day-of-month - There are between 28 and 31 days in each of the ISO month, numbered from 1 to 31. Months 4, 6, 9 and 11 have 30 days, Months 1, 3, 5, 7, 8, 10 and 12 have 31 days. Month 2 has 28 days, or 29 in a leap year.
  • day-of-year - There are 365 days in a standard ISO year and 366 in a leap year. The days are numbered from 1 to 365 or 1 to 366.
  • leap-year - Leap years occur every 4 years, except where the year is divisble by 100 and not divisble by 400.

Summary

Fields

public static final IsoChronology INSTANCE

Singleton instance of the ISO chronology.

Public methods

LocalDate date(int prolepticYear, int month, int dayOfMonth)

Obtains an ISO local date from the proleptic-year, month-of-year and day-of-month fields.

LocalDate date(Era era, int yearOfEra, int month, int dayOfMonth)

Obtains an ISO local date from the era, year-of-era, month-of-year and day-of-month fields.

LocalDate date(TemporalAccessor temporal)

Obtains an ISO local date from another date-time object.

LocalDate dateEpochDay(long epochDay)

Obtains an ISO local date from the epoch-day.

LocalDate dateNow(ZoneId zone)

Obtains the current ISO local date from the system clock in the specified time-zone.

LocalDate dateNow()

Obtains the current ISO local date from the system clock in the default time-zone.

LocalDate dateNow(Clock clock)

Obtains the current ISO local date from the specified clock.

LocalDate dateYearDay(Era era, int yearOfEra, int dayOfYear)

Obtains an ISO local date from the era, year-of-era and day-of-year fields.

LocalDate dateYearDay(int prolepticYear, int dayOfYear)

Obtains an ISO local date from the proleptic-year and day-of-year fields.

IsoEra eraOf(int eraValue)
List<Era> eras()
String getCalendarType()

Gets the calendar type of the underlying calendar system - 'iso8601'.

String getId()

Gets the ID of the chronology - 'ISO'.

boolean isLeapYear(long prolepticYear)

Checks if the year is a leap year, according to the ISO proleptic calendar system rules.

LocalDateTime localDateTime(TemporalAccessor temporal)

Obtains an ISO local date-time from another date-time object.

Period period(int years, int months, int days)

Obtains a period for this chronology based on years, months and days.

int prolepticYear(Era era, int yearOfEra)
ValueRange range(ChronoField field)
LocalDate resolveDate(Map<TemporalFieldLong> fieldValues, ResolverStyle resolverStyle)

Resolves parsed ChronoField values into a date during parsing.

ZonedDateTime zonedDateTime(TemporalAccessor temporal)

Obtains an ISO zoned date-time from another date-time object.

ZonedDateTime zonedDateTime(Instant instant, ZoneId zone)

Obtains an ISO zoned date-time in this chronology from an Instant.

Inherited methods

Fields

INSTANCE

added in API level 26
public static final IsoChronology INSTANCE

Singleton instance of the ISO chronology.

Public methods

date

added in API level 26
public LocalDate date (int prolepticYear, 
                int month, 
                int dayOfMonth)

Obtains an ISO local date from the proleptic-year, month-of-year and day-of-month fields.

This is equivalent to LocalDate.of(int, int, int).

Parameters
prolepticYear int: the ISO proleptic-year

month int: the ISO month-of-year

dayOfMonth int: the ISO day-of-month

Returns
LocalDate the ISO local date, not null

Throws
DateTimeException if unable to create the date

date

added in API level 26
public LocalDate date (Era era, 
                int yearOfEra, 
                int month, 
                int dayOfMonth)

Obtains an ISO local date from the era, year-of-era, month-of-year and day-of-month fields.

Parameters
era Era: the ISO era, not null

yearOfEra int: the ISO year-of-era

month int: the ISO month-of-year

dayOfMonth int: the ISO day-of-month

Returns
LocalDate the ISO local date, not null

Throws
DateTimeException if unable to create the date
ClassCastException if the type of era is not IsoEra

date

added in API level 26
public LocalDate date (TemporalAccessor temporal)

Obtains an ISO local date from another date-time object.

This is equivalent to LocalDate.from(TemporalAccessor).

Parameters
temporal TemporalAccessor: the date-time object to convert, not null

Returns
LocalDate the ISO local date, not null

Throws
DateTimeException if unable to create the date

dateEpochDay

added in API level 26
public LocalDate dateEpochDay (long epochDay)

Obtains an ISO local date from the epoch-day.

This is equivalent to LocalDate.ofEpochDay(long).

Parameters
epochDay long: the epoch day

Returns
LocalDate the ISO local date, not null

Throws
DateTimeException if unable to create the date

dateNow

added in API level 26
public LocalDate dateNow (ZoneId zone)

Obtains the current ISO local date from the system clock in the specified time-zone.

This will query the 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.

Parameters
zone ZoneId

Returns
LocalDate the current ISO local date using the system clock, not null

Throws
DateTimeException if unable to create the date

dateNow

added in API level 26
public LocalDate dateNow ()

Obtains the current ISO local date from the system clock in the default time-zone.

This will query the 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.

Returns
LocalDate the current ISO local date using the system clock and default time-zone, not null

Throws
DateTimeException if unable to create the date

dateNow

added in API level 26
public LocalDate dateNow (Clock clock)

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 dependency injection.

Parameters
clock Clock: the clock to use, not null

Returns
LocalDate the current ISO local date, not null

Throws
DateTimeException if unable to create the date

dateYearDay

added in API level 26
public LocalDate dateYearDay (Era era, 
                int yearOfEra, 
                int dayOfYear)

Obtains an ISO local date from the era, year-of-era and day-of-year fields.

Parameters
era Era: the ISO era, not null

yearOfEra int: the ISO year-of-era

dayOfYear int: the ISO day-of-year

Returns
LocalDate the ISO local date, not null

Throws
DateTimeException if unable to create the date

dateYearDay

added in API level 26
public LocalDate dateYearDay (int prolepticYear, 
                int dayOfYear)

Obtains an ISO local date from the proleptic-year and day-of-year fields.

This is equivalent to LocalDate.ofYearDay(int, int).

Parameters
prolepticYear int: the ISO proleptic-year

dayOfYear int: the ISO day-of-year

Returns
LocalDate the ISO local date, not null

Throws
DateTimeException if unable to create the date

eraOf

added in API level 26
public IsoEra eraOf (int eraValue)

Parameters
eraValue int

Returns
IsoEra

eras

added in API level 26
public List<Era> eras ()

Returns
List<Era>

getCalendarType

added in API level 26
public String getCalendarType ()

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 Chronology using Chronology.of(String). It can also be used as part of a locale, accessible via Locale.getUnicodeLocaleType(String) with the key 'ca'.

Returns
String the calendar system type - 'iso8601'

See also:

getId

added in API level 26
public String getId ()

Gets the ID of the chronology - 'ISO'.

The ID uniquely identifies the Chronology. It can be used to lookup the Chronology using Chronology.of(String).

Returns
String the chronology ID - 'ISO'

See also:

isLeapYear

added in API level 26
public boolean isLeapYear (long prolepticYear)

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.

Parameters
prolepticYear long: the ISO proleptic year to check

Returns
boolean true if the year is leap, false otherwise

localDateTime

added in API level 26
public LocalDateTime localDateTime (TemporalAccessor temporal)

Obtains an ISO local date-time from another date-time object.

This is equivalent to LocalDateTime.from(TemporalAccessor).

Parameters
temporal TemporalAccessor: the date-time object to convert, not null

Returns
LocalDateTime the ISO local date-time, not null

Throws
DateTimeException if unable to create the date-time

period

added in API level 26
public Period period (int years, 
                int months, 
                int days)

Obtains a period for this chronology based on years, months and days.

This returns a period tied to the ISO chronology using the specified years, months and days. See Period for further details.

Parameters
years int: the number of years, may be negative

months int: the number of years, may be negative

days int: the number of years, may be negative

Returns
Period the period in terms of this chronology, not nullthe ISO period, not null

prolepticYear

added in API level 26
public int prolepticYear (Era era, 
                int yearOfEra)

Parameters
era Era

yearOfEra int

Returns
int

range

added in API level 26
public ValueRange range (ChronoField field)

Parameters
field ChronoField

Returns
ValueRange

resolveDate

added in API level 26
public LocalDate resolveDate (Map<TemporalFieldLong> fieldValues, 
                ResolverStyle resolverStyle)

Resolves parsed ChronoField values into a date during parsing.

Most TemporalField implementations are resolved using the resolve method on the field. By contrast, the ChronoField class defines fields that only have meaning relative to the chronology. As such, ChronoField date fields are resolved here in the context of a specific chronology.

ChronoField instances on the ISO calendar system are resolved as follows.

  • EPOCH_DAY - If present, this is converted to a LocalDate and all other date fields are then cross-checked against the date.
  • PROLEPTIC_MONTH - If present, then it is split into the YEAR and MONTH_OF_YEAR. If the mode is strict or smart then the field is validated.
  • YEAR_OF_ERA and ERA - If both are present, then they are combined to form a YEAR. In lenient mode, the YEAR_OF_ERA range is not validated, in smart and strict mode it is. The ERA is validated for range in all three modes. If only the YEAR_OF_ERA is present, and the mode is smart or lenient, then the current era (CE/AD) is assumed. In strict mode, no era is assumed and the YEAR_OF_ERA is left untouched. If only the ERA is present, then it is left untouched.
  • YEAR, MONTH_OF_YEAR and DAY_OF_MONTH - If all three are present, then they are combined to form a LocalDate. In all three modes, the YEAR is validated. If the mode is smart or strict, then the month and day are validated, with the day validated from 1 to 31. If the mode is lenient, then the date is combined in a manner equivalent to creating a date on the first of January in the requested year, then adding the difference in months, then the difference in days. If the mode is smart, and the day-of-month is greater than the maximum for the year-month, then the day-of-month is adjusted to the last day-of-month. If the mode is strict, then the three fields must form a valid date.
  • YEAR and DAY_OF_YEAR - If both are present, then they are combined to form a LocalDate. In all three modes, the YEAR is validated. If the mode is lenient, then the date is combined in a manner equivalent to creating a date on the first of January in the requested year, then adding the difference in days. If the mode is smart or strict, then the two fields must form a valid date.
  • YEAR, MONTH_OF_YEAR, ALIGNED_WEEK_OF_MONTH and ALIGNED_DAY_OF_WEEK_IN_MONTH - If all four are present, then they are combined to form a LocalDate. In all three modes, the YEAR is validated. If the mode is lenient, then the date is combined in a manner equivalent to creating a date on the first of January in the requested year, then adding the difference in months, then the difference in weeks, then in days. If the mode is smart or strict, then the all four fields are validated to their outer ranges. The date is then combined in a manner equivalent to creating a date on the first day of the requested year and month, then adding the amount in weeks and days to reach their values. If the mode is strict, the date is additionally validated to check that the day and week adjustment did not change the month.
  • YEAR, MONTH_OF_YEAR, ALIGNED_WEEK_OF_MONTH and DAY_OF_WEEK - If all four are present, then they are combined to form a LocalDate. The approach is the same as described above for years, months and weeks in ALIGNED_DAY_OF_WEEK_IN_MONTH. The day-of-week is adjusted as the next or same matching day-of-week once the years, months and weeks have been handled.
  • YEAR, ALIGNED_WEEK_OF_YEAR and ALIGNED_DAY_OF_WEEK_IN_YEAR - If all three are present, then they are combined to form a LocalDate. In all three modes, the YEAR is validated. If the mode is lenient, then the date is combined in a manner equivalent to creating a date on the first of January in the requested year, then adding the difference in weeks, then in days. If the mode is smart or strict, then the all three fields are validated to their outer ranges. The date is then combined in a manner equivalent to creating a date on the first day of the requested year, then adding the amount in weeks and days to reach their values. If the mode is strict, the date is additionally validated to check that the day and week adjustment did not change the year.
  • YEAR, ALIGNED_WEEK_OF_YEAR and DAY_OF_WEEK - If all three are present, then they are combined to form a LocalDate. The approach is the same as described above for years and weeks in ALIGNED_DAY_OF_WEEK_IN_YEAR. The day-of-week is adjusted as the next or same matching day-of-week once the years and weeks have been handled.

Parameters
fieldValues Map: the map of fields to values, which can be updated, not null

resolverStyle ResolverStyle: the requested type of resolve, not null

Returns
LocalDate the resolved date, null if insufficient information to create a date

Throws
DateTimeException if the date cannot be resolved, typically because of a conflict in the input data

zonedDateTime

added in API level 26
public ZonedDateTime zonedDateTime (TemporalAccessor temporal)

Obtains an ISO zoned date-time from another date-time object.

This is equivalent to ZonedDateTime.from(TemporalAccessor).

Parameters
temporal TemporalAccessor: the date-time object to convert, not null

Returns
ZonedDateTime the ISO zoned date-time, not null

Throws
DateTimeException if unable to create the date-time

zonedDateTime

added in API level 26
public ZonedDateTime zonedDateTime (Instant instant, 
                ZoneId zone)

Obtains an ISO zoned date-time in this chronology from an Instant.

This is equivalent to ZonedDateTime.ofInstant(Instant, ZoneId).

Parameters
instant Instant: the instant to create the date-time from, not null

zone ZoneId: the time-zone, not null

Returns
ZonedDateTime the zoned date-time, not null

Throws
DateTimeException if the result exceeds the supported range