Module java.base
Package java.time.chrono

Class IsoChronology

java.lang.Object
java.time.chrono.AbstractChronology
java.time.chrono.IsoChronology
All Implemented Interfaces:
Serializable, Comparable<Chronology>, Chronology
public final class IsoChronology extends AbstractChronology implements Serializable
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.
Implementation Requirements:
This class is immutable and thread-safe.
Since:
1.8
See Also:

  • Field Details

    • INSTANCE

      public static final IsoChronology INSTANCE
      Singleton instance of the ISO chronology.

  • Method Details

    • getId

      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).

      Specified by:
      getId in interface Chronology
      Returns:
      the chronology ID - 'ISO'
      See Also:

    • getCalendarType

      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'.

      Specified by:
      getCalendarType in interface Chronology
      Returns:
      the calendar system type - 'iso8601'
      See Also:

    • date

      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.
      Specified by:
      date in interface Chronology
      Parameters:
      era - the ISO era, not null
      yearOfEra - the ISO year-of-era
      month - the ISO month-of-year
      dayOfMonth - the ISO day-of-month
      Returns:
      the ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date
      ClassCastException - if the type of era is not IsoEra

    • date

      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).

      Specified by:
      date in interface Chronology
      Parameters:
      prolepticYear - the ISO proleptic-year
      month - the ISO month-of-year
      dayOfMonth - the ISO day-of-month
      Returns:
      the ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date

    • dateYearDay

      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.
      Specified by:
      dateYearDay in interface Chronology
      Parameters:
      era - the ISO era, not null
      yearOfEra - the ISO year-of-era
      dayOfYear - the ISO day-of-year
      Returns:
      the ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date

    • dateYearDay

      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).

      Specified by:
      dateYearDay in interface Chronology
      Parameters:
      prolepticYear - the ISO proleptic-year
      dayOfYear - the ISO day-of-year
      Returns:
      the ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date

    • dateEpochDay

      public LocalDate dateEpochDay(long epochDay)
      Obtains an ISO local date from the epoch-day.

      This is equivalent to LocalDate.ofEpochDay(long).

      Specified by:
      dateEpochDay in interface Chronology
      Parameters:
      epochDay - the epoch day
      Returns:
      the ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date

    • date

      public LocalDate date(TemporalAccessor temporal)
      Obtains an ISO local date from another date-time object.

      This is equivalent to LocalDate.from(TemporalAccessor).

      Specified by:
      date in interface Chronology
      Parameters:
      temporal - the date-time object to convert, not null
      Returns:
      the ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date
      See Also:

    • epochSecond

      public long epochSecond(int prolepticYear, int month, int dayOfMonth, int hour, int minute, int second, ZoneOffset zoneOffset)
      Gets the number of seconds from the epoch of 1970-01-01T00:00:00Z.

      The number of seconds is calculated using the year, month, day-of-month, hour, minute, second, and zoneOffset.

      Specified by:
      epochSecond in interface Chronology
      Parameters:
      prolepticYear - the year, from MIN_YEAR to MAX_YEAR
      month - the month-of-year, from 1 to 12
      dayOfMonth - the day-of-month, from 1 to 31
      hour - the hour-of-day, from 0 to 23
      minute - the minute-of-hour, from 0 to 59
      second - the second-of-minute, from 0 to 59
      zoneOffset - the zone offset, not null
      Returns:
      the number of seconds relative to 1970-01-01T00:00:00Z, may be negative
      Throws:
      DateTimeException - if the value of any argument is out of range, or if the day-of-month is invalid for the month-of-year
      Since:
      9

    • localDateTime

      public LocalDateTime localDateTime(TemporalAccessor temporal)
      Obtains an ISO local date-time from another date-time object.

      This is equivalent to LocalDateTime.from(TemporalAccessor).

      Specified by:
      localDateTime in interface Chronology
      Parameters:
      temporal - the date-time object to convert, not null
      Returns:
      the ISO local date-time, not null
      Throws:
      DateTimeException - if unable to create the date-time
      See Also:

    • zonedDateTime

      public ZonedDateTime zonedDateTime(TemporalAccessor temporal)
      Obtains an ISO zoned date-time from another date-time object.

      This is equivalent to ZonedDateTime.from(TemporalAccessor).

      Specified by:
      zonedDateTime in interface Chronology
      Parameters:
      temporal - the date-time object to convert, not null
      Returns:
      the ISO zoned date-time, not null
      Throws:
      DateTimeException - if unable to create the date-time
      See Also:

    • zonedDateTime

      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).

      Specified by:
      zonedDateTime in interface Chronology
      Parameters:
      instant - the instant to create the date-time from, not null
      zone - the time-zone, not null
      Returns:
      the zoned date-time, not null
      Throws:
      DateTimeException - if the result exceeds the supported range

    • dateNow

      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.

      Specified by:
      dateNow in interface Chronology
      Returns:
      the current ISO local date using the system clock and default time-zone, not null
      Throws:
      DateTimeException - if unable to create the date

    • dateNow

      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.

      Specified by:
      dateNow in interface Chronology
      Parameters:
      zone - the zone ID to use, not null
      Returns:
      the current ISO local date using the system clock, not null
      Throws:
      DateTimeException - if unable to create the date

    • dateNow

      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.

      Specified by:
      dateNow in interface Chronology
      Parameters:
      clock - the clock to use, not null
      Returns:
      the current ISO local date, not null
      Throws:
      DateTimeException - if unable to create the date

    • isLeapYear

      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.

      Specified by:
      isLeapYear in interface Chronology
      Parameters:
      prolepticYear - the ISO proleptic year to check
      Returns:
      true if the year is leap, false otherwise

    • prolepticYear

      public int prolepticYear(Era era, int yearOfEra)
      Description copied from interface: Chronology
      Calculates the proleptic-year given the era and year-of-era.

      This combines the era and year-of-era into the single proleptic-year field.

      If the chronology makes active use of eras, such as JapaneseChronology then the year-of-era will be validated against the era. For other chronologies, validation is optional.

      Specified by:
      prolepticYear in interface Chronology
      Parameters:
      era - the era of the correct type for the chronology, not null
      yearOfEra - the chronology year-of-era
      Returns:
      the proleptic-year

    • eraOf

      public IsoEra eraOf(int eraValue)
      Description copied from interface: Chronology
      Creates the chronology era object from the numeric value.

      The era is, conceptually, the largest division of the time-line. Most calendar systems have a single epoch dividing the time-line into two eras. However, some have multiple eras, such as one for the reign of each leader. The exact meaning is determined by the chronology according to the following constraints.

      The era in use at 1970-01-01 must have the value 1. Later eras must have sequentially higher values. Earlier eras must have sequentially lower values. Each chronology must refer to an enum or similar singleton to provide the era values.

      This method returns the singleton era of the correct type for the specified era value.

      Specified by:
      eraOf in interface Chronology
      Parameters:
      eraValue - the era value
      Returns:
      the calendar system era, not null

    • eras

      public List<Era> eras()
      Description copied from interface: Chronology
      Gets the list of eras for the chronology.

      Most calendar systems have an era, within which the year has meaning. If the calendar system does not support the concept of eras, an empty list must be returned.

      Specified by:
      eras in interface Chronology
      Returns:
      the list of eras for the chronology, may be immutable, not null

    • resolveDate

      public LocalDate resolveDate(Map<TemporalField,Long> 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.
      Specified by:
      resolveDate in interface Chronology
      Overrides:
      resolveDate in class AbstractChronology
      Parameters:
      fieldValues - the map of fields to values, which can be updated, not null
      resolverStyle - the requested type of resolve, not null
      Returns:
      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

    • range

      public ValueRange range(ChronoField field)
      Description copied from interface: Chronology
      Gets the range of valid values for the specified field.

      All fields can be expressed as a long integer. This method returns an object that describes the valid range for that value.

      Note that the result only describes the minimum and maximum valid values and it is important not to read too much into them. For example, there could be values within the range that are invalid for the field.

      This method will return a result whether or not the chronology supports the field.

      Specified by:
      range in interface Chronology
      Parameters:
      field - the field to get the range for, not null
      Returns:
      the range of valid values for the field, not null

    • period

      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.

      Specified by:
      period in interface Chronology
      Parameters:
      years - the number of years, may be negative
      months - the number of years, may be negative
      days - the number of years, may be negative
      Returns:
      the ISO period, not null