Chronology

A calendar system, used to organize and identify dates.

The main date and time API is built on the ISO calendar system. This class operates behind the scenes to represent the general concept of a calendar system. For example, the Japanese, Minguo, Thai Buddhist and others.

Most other calendar systems also operate on the shared concepts of year, month and day, linked to the cycles of the Earth around the Sun, and the Moon around the Earth. These shared concepts are defined by ChronoField and are availalbe for use by any Chronology implementation:

val isoDate: LocalDate = ...
val thaiDate: ChronoLocalDate[ThaiBuddhistChrono] = ...
val isoYear: Int = isoDate.get(ChronoField.YEAR);
val thaiYear: Int = thaiDate.get(ChronoField.YEAR);

As shown, although the date objects are in different calendar systems, represented by different Chronology instances, both can be queried using the same constant on ChronoField. For a full discussion of the implications of this, see ChronoLocalDate. In general, the advice is to use the known ISO-based LocalDate, rather than ChronoLocalDate.

While a Chronology object typically uses ChronoField and is based on an era, year-of-era, month-of-year, day-of-month model of a date, this is not required. A Chronology instance may represent a totally different kind of calendar system, such as the Mayan.

In practical terms, the Chronology instance also acts as a factory. The #of(String) method allows an instance to be looked up by identifier, while the #ofLocale(Locale) method allows lookup by locale.

The Chronology instance provides a set of methods to create ChronoLocalDate instances. The date classes are used to manipulate specific dates.

dateNow()
dateNow(clock)
dateNow(zone)
int, int) date(yearProleptic, month, day)
int, int, int) date(era, yearOfEra, month, day)
int) dateYearDay(yearProleptic, dayOfYear)
int, int) dateYearDay(era, yearOfEra, dayOfYear)
date(TemporalAccessor)

Adding New Calendars The set of available chronologies can be extended by applications. Adding a new calendar system requires the writing of an implementation of Chronology, ChronoLocalDate and Era. The majority of the logic specific to the calendar system will be in ChronoLocalDate. The Chronology subclass acts as a factory.

To permit the discovery of additional chronologies, the ServiceLoader is used. A file must be added to the META-INF/services directory with the name 'org.threeten.bp.chrono.Chrono' listing the implementation classes. See the ServiceLoader for more details on service loading. For lookup by id or calendarType, the system provided calendars are found first followed by application provided calendars.

Each chronology must define a chronology ID that is unique within the system. If the chronology represents a calendar system defined by the Unicode Locale Data Markup Language (LDML) specification then that calendar type should also be specified.

Specification for implementors

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.

Linear Supertypes

Ordered[Chronology], Comparable[Chronology], AnyRef, Any

Known Subclasses

AbstractChronology, HijrahChronology, IsoChronology, JapaneseChronology, MinguoChronology, ThaiBuddhistChronology

Abstract Value Members

abstract def date(temporal: TemporalAccessor): ChronoLocalDate

Obtains a local date in this chronology from another temporal object.
Obtains a local date in this chronology from another temporal object.
This creates a date in this chronology based on the specified TemporalAccessor.
The standard mechanism for conversion between date types is the local epoch-day field.
temporal
the temporal object to convert, not null
returns
the local date in this chronology, not null

Exceptions thrown
DateTimeException if unable to create the date
abstract def date(prolepticYear: Int, month: Int, dayOfMonth: Int): ChronoLocalDate

Obtains a local date in this chronology from the proleptic-year, month-of-year and day-of-month fields.
Obtains a local date in this chronology from the proleptic-year, month-of-year and day-of-month fields.
prolepticYear
the chronology proleptic-year
month
the chronology month-of-year
dayOfMonth
the chronology day-of-month
returns
the local date in this chronology, not null

Exceptions thrown
DateTimeException if unable to create the date
abstract def dateEpochDay(epochDay: Long): ChronoLocalDate

Obtains a local date in this chronology from the epoch-day.
Obtains a local date in this chronology from the epoch-day.
The definition of EPOCH_DAY is the same for all calendar systems, thus it can be used for conversion.
epochDay
the epoch day
returns
the local date in this chronology, not null

Exceptions thrown
DateTimeException if unable to create the date
abstract def dateYearDay(prolepticYear: Int, dayOfYear: Int): ChronoLocalDate

Obtains a local date in this chronology from the proleptic-year and day-of-year fields.
Obtains a local date in this chronology from the proleptic-year and day-of-year fields.
prolepticYear
the chronology proleptic-year
dayOfYear
the chronology day-of-year
returns
the local date in this chronology, not null

Exceptions thrown
DateTimeException if unable to create the date
abstract def eraOf(eraValue: Int): Era

Creates the chronology era object from the numeric value.
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.
eraValue
the era value
returns
the calendar system era, not null

Exceptions thrown
DateTimeException if unable to create the era
abstract def eras: List[Era]

Gets the list of eras for the 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.
returns
the list of eras for the chronology, may be immutable, not null
abstract def getCalendarType: String

Gets the calendar type of the underlying calendar system.
Gets the calendar type of the underlying calendar system.
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 #of(String). It can also be used as part of a locale, accessible via Locale#getUnicodeLocaleType(String) with the key 'ca'.
returns
the calendar system type, null if the calendar is not defined by LDML

See also
#getId()
abstract def getId: String

Gets the ID of the chronology.
Gets the ID of the chronology.
The ID uniquely identifies the Chronology. It can be used to lookup the Chronology using #of(String).
returns
the chronology ID, not null

See also
#getCalendarType()
abstract def isLeapYear(prolepticYear: Long): Boolean

Checks if the specified year is a leap year.
Checks if the specified year is a leap year.
A leap-year is a year of a longer length than normal. The exact meaning is determined by the chronology according to the following constraints.
- a leap-year must imply a year-length longer than a non leap-year.
- a chronology that does not support the concept of a year must return false.
prolepticYear
the proleptic-year to check, not validated for range
returns
true if the year is a leap year
abstract def prolepticYear(era: Era, yearOfEra: Int): Int

Calculates the proleptic-year given the era and year-of-era.
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.
era
the era of the correct type for the chronology, not null
yearOfEra
the chronology year-of-era
returns
the proleptic-year

Exceptions thrown
ClassCastException if the { @code era} is not of the correct type for the chronology
DateTimeException if unable to convert
abstract def range(field: ChronoField): ValueRange

Gets the range of valid values for the specified field.
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.
field
the field to get the range for, not null
returns
the range of valid values for the field, not null

Exceptions thrown
DateTimeException if the range for the field cannot be obtained
abstract def resolveDate(fieldValues: Map[TemporalField, Long], resolverStyle: ResolverStyle): ChronoLocalDate

Resolves parsed ChronoField values into a date during parsing.
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.
The default implementation, which explains typical resolve behaviour, is provided in AbstractChronology.
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

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

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

Definition Classes
AnyRef → Any
def <(that: Chronology): Boolean

Definition Classes
Ordered
def <=(that: Chronology): Boolean

Definition Classes
Ordered
final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any
def >(that: Chronology): Boolean

Definition Classes
Ordered
def >=(that: Chronology): Boolean

Definition Classes
Ordered
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
def compare(other: Chronology): Int

Compares this chronology to another chronology.
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.
The default implementation compares the chronology ID. Subclasses must compare any additional state that they store.
other
the other chronology to compare to, not null
returns
the comparator value, negative if less, positive if greater

Definition Classes
Chronology → Ordered
def compareTo(that: Chronology): Int

Definition Classes
Ordered → Comparable
def date(era: Era, yearOfEra: Int, month: Int, dayOfMonth: Int): ChronoLocalDate

Obtains a local date in this chronology from the era, year-of-era, month-of-year and day-of-month fields.
Obtains a local date in this chronology from the era, year-of-era, month-of-year and day-of-month fields.
era
the era of the correct type for the chronology, not null
yearOfEra
the chronology year-of-era
month
the chronology month-of-year
dayOfMonth
the chronology day-of-month
returns
the local date in this chronology, not null

Exceptions thrown
ClassCastException if the { @code era} is not of the correct type for the chronology
DateTimeException if unable to create the date
def dateNow(clock: Clock): ChronoLocalDate

Obtains the current local date in this chronology from the specified clock.
Obtains the current local date in this chronology 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.
clock
the clock to use, not null
returns
the current local date, not null

Exceptions thrown
DateTimeException if unable to create the date
def dateNow(zone: ZoneId): ChronoLocalDate

Obtains the current local date in this chronology from the system clock in the specified time-zone.
Obtains the current local date in this chronology 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.
zone
the zone ID to use, not null
returns
the current local date using the system clock, not null

Exceptions thrown
DateTimeException if unable to create the date
def dateNow: ChronoLocalDate

Obtains the current local date in this chronology from the system clock in the default time-zone.
Obtains the current local date in this chronology 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.
This implementation uses #dateNow(Clock).
returns
the current local date using the system clock and default time-zone, not null

Exceptions thrown
DateTimeException if unable to create the date
def dateYearDay(era: Era, yearOfEra: Int, dayOfYear: Int): ChronoLocalDate

Obtains a local date in this chronology from the era, year-of-era and day-of-year fields.
Obtains a local date in this chronology from the era, year-of-era and day-of-year fields.
era
the era of the correct type for the chronology, not null
yearOfEra
the chronology year-of-era
dayOfYear
the chronology day-of-year
returns
the local date in this chronology, not null

Exceptions thrown
ClassCastException if the { @code era} is not of the correct type for the chronology
DateTimeException if unable to create the date
final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef
def equals(obj: Any): Boolean

Checks if this chronology is equal to another chronology.
Checks if this chronology is equal to another chronology.
The comparison is based on the entire state of the object.
The default implementation checks the type and calls #compareTo(Chronology).
obj
the object to check, null returns false
returns
true if this is equal to the other chronology

Definition Classes
Chronology → AnyRef → Any
def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( classOf[java.lang.Throwable] )
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def getDisplayName(style: TextStyle, locale: Locale): String

Gets the textual representation of this chronology.
Gets the textual representation of this chronology.
This returns the textual name used to identify the chronology. The parameters control the style of the returned text and the locale.
style
the style of the text required, not null
locale
the locale to use, not null
returns
the text value of the chronology, not null
def hashCode(): Int

A hash code for this chronology.
A hash code for this chronology.
The default implementation is based on the ID and class. Subclasses should add any additional state that they store.
returns
a suitable hash code

Definition Classes
Chronology → AnyRef → Any
final def isInstanceOf[T0]: Boolean

Definition Classes
Any
def localDateTime(temporal: TemporalAccessor): ChronoLocalDateTime[_]

Obtains a local date-time in this chronology from another temporal object.
Obtains a local date-time in this chronology from another temporal object.
This creates a date-time in this chronology based on the specified TemporalAccessor.
The date of the date-time should be equivalent to that obtained by calling #date(TemporalAccessor). The standard mechanism for conversion between time types is the nano-of-day field.
temporal
the temporal object to convert, not null
returns
the local date-time in this chronology, not null

Exceptions thrown
DateTimeException if unable to create the date-time
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
def period(years: Int, months: Int, days: Int): ChronoPeriod

Obtains a period for this chronology based on years, months and days.
Obtains a period for this chronology based on years, months and days.
This returns a period tied to this chronology using the specified years, months and days. All supplied chronologies use periods based on years, months and days, however the ChronoPeriod API allows the period to be represented using other units.
The default implementation returns an implementation class suitable for most calendar systems. It is based solely on the three units. Normalization, addition and subtraction derive the number of months in a year from the #range(ChronoField). If the number of months within a year is fixed, then the calculation approach for addition, subtraction and normalization is slightly different.
If implementing an unusual calendar system that is not based on years, months and days, or where you want direct control, then the ChronoPeriod interface must be directly implemented.
The returned period is immutable and thread-safe.
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 period in terms of this chronology, not null
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toString(): String

Outputs this chronology as a String, using the ID.
Outputs this chronology as a String, using the ID.
returns
a string representation of this chronology, not null

Definition Classes
Chronology → AnyRef → Any
final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )
def zonedDateTime(instant: Instant, zone: ZoneId): ChronoZonedDateTime[_ <: ChronoLocalDate]

Obtains a zoned date-time in this chronology from an Instant.
Obtains a zoned date-time in this chronology from an Instant.
This creates a zoned date-time with the same instant as that specified.
instant
the instant to create the date-time from, not null
zone
the time-zone, not null
returns
the zoned date-time, not null

Exceptions thrown
DateTimeException if the result exceeds the supported range
def zonedDateTime(temporal: TemporalAccessor): ChronoZonedDateTime[_]

Obtains a zoned date-time in this chronology from another temporal object.
Obtains a zoned date-time in this chronology from another temporal object.
This creates a date-time in this chronology based on the specified TemporalAccessor.
This should obtain a ZoneId using ZoneId#from(TemporalAccessor). The date-time should be obtained by obtaining an Instant. If that fails, the local date-time should be used.
temporal
the temporal object to convert, not null
returns
the zoned date-time in this chronology, not null

Exceptions thrown
DateTimeException if unable to create the date-time

Related Docs: object Chronology | package chrono

trait Chronology extends Ordered[Chronology]

Specification for implementors

Abstract Value Members

abstract def date(temporal: TemporalAccessor): ChronoLocalDate

abstract def date(prolepticYear: Int, month: Int, dayOfMonth: Int): ChronoLocalDate

abstract def dateEpochDay(epochDay: Long): ChronoLocalDate

abstract def dateYearDay(prolepticYear: Int, dayOfYear: Int): ChronoLocalDate

abstract def eraOf(eraValue: Int): Era

abstract def eras: List[Era]

abstract def getCalendarType: String

abstract def getId: String

abstract def isLeapYear(prolepticYear: Long): Boolean

abstract def prolepticYear(era: Era, yearOfEra: Int): Int

abstract def range(field: ChronoField): ValueRange

abstract def resolveDate(fieldValues: Map[TemporalField, Long], resolverStyle: ResolverStyle): ChronoLocalDate

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

def <(that: Chronology): Boolean

def <=(that: Chronology): Boolean

final def ==(arg0: Any): Boolean

def >(that: Chronology): Boolean

def >=(that: Chronology): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

def compare(other: Chronology): Int

def compareTo(that: Chronology): Int

def date(era: Era, yearOfEra: Int, month: Int, dayOfMonth: Int): ChronoLocalDate

def dateNow(clock: Clock): ChronoLocalDate

def dateNow(zone: ZoneId): ChronoLocalDate

def dateNow: ChronoLocalDate

def dateYearDay(era: Era, yearOfEra: Int, dayOfYear: Int): ChronoLocalDate

final def eq(arg0: AnyRef): Boolean

def equals(obj: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def getDisplayName(style: TextStyle, locale: Locale): String

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

def localDateTime(temporal: TemporalAccessor): ChronoLocalDateTime[_]

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

def period(years: Int, months: Int, days: Int): ChronoPeriod

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

def zonedDateTime(instant: Instant, zone: ZoneId): ChronoZonedDateTime[_ <: ChronoLocalDate]

def zonedDateTime(temporal: TemporalAccessor): ChronoZonedDateTime[_]

Inherited from Ordered[Chronology]

Inherited from Comparable[Chronology]

Inherited from AnyRef

Inherited from Any

Ungrouped