Module java.base
Package java.time.chrono

Class AbstractChronology

  • All Implemented Interfaces:
    Comparable<Chronology>, Chronology
    Direct Known Subclasses:
    HijrahChronology, IsoChronology, JapaneseChronology, MinguoChronology, ThaiBuddhistChronology
    public abstract class AbstractChronology
extends Object
implements Chronology
    An abstract implementation of a calendar system, used to organize and identify dates.

    The main date and time API is built on the ISO calendar system. The chronology operates behind the scenes to represent the general concept of a calendar system.

    See Chronology for more details.

    Implementation Requirements:
    This class is separated from the Chronology interface so that the static methods are not inherited. While Chronology can be implemented directly, it is strongly recommended to extend this abstract class instead.

    This class must be implemented with care to ensure other classes operate correctly. All implementations that can be instantiated must be final, immutable and thread-safe. Subclasses should be Serializable wherever possible.

    Since:
    1.8

    • Constructor Detail

      • AbstractChronology

        protected AbstractChronology()
        Creates an instance.

    • Method Detail

      • resolveDate

        public ChronoLocalDate 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 are resolved by this method, which may be overridden in subclasses.

        • EPOCH_DAY - If present, this is converted to a date 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 last available era 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 date. In all three modes, the YEAR is validated. If the mode is smart or strict, then the month and day are validated. If the mode is lenient, then the date is combined in a manner equivalent to creating a date on the first day of the first month 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 date. 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 day of 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 date. 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 day of the first month 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 date. 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 date. 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 day of 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 date. 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.

        The default implementation is suitable for most calendar systems. If ChronoField.YEAR_OF_ERA is found without an ChronoField.ERA then the last era in Chronology.eras() is used. The implementation assumes a 7 day week, that the first day-of-month has the value 1, that first day-of-year has the value 1, and that the first of the month and year always exists.

        Specified by:
        resolveDate in interface Chronology
        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

      • compareTo

        public int compareTo​(Chronology other)
        Compares this chronology to another chronology.

        The comparison order first by the chronology ID string, then by any additional information specific to the subclass. It is "consistent with equals", as defined by Comparable.

        Specified by:
        compareTo in interface Chronology
        Specified by:
        compareTo in interface Comparable<Chronology>
        Implementation Requirements:
        This implementation compares the chronology ID. Subclasses must compare any additional state that they store.
        Parameters:
        other - the other chronology to compare to, not null
        Returns:
        the comparator value, negative if less, positive if greater

      • equals

        public boolean equals​(Object obj)
        Checks if this chronology is equal to another chronology.

        The comparison is based on the entire state of the object.

        Specified by:
        equals in interface Chronology
        Overrides:
        equals in class Object
        Implementation Requirements:
        This implementation checks the type and calls compareTo(java.time.chrono.Chronology).
        Parameters:
        obj - the object to check, null returns false
        Returns:
        true if this is equal to the other chronology
        See Also:
        Object.hashCode(), HashMap

      • toString

        public String toString()
        Outputs this chronology as a String, using the chronology ID.
        Specified by:
        toString in interface Chronology
        Overrides:
        toString in class Object
        Returns:
        a string representation of this chronology, not null