- All Superinterfaces:
Comparable<Chronology>
- All Known Implementing Classes:
AbstractChronology
,HijrahChronology
,IsoChronology
,JapaneseChronology
,MinguoChronology
,ThaiBuddhistChronology
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. 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 available
for use by any Chronology
implementation:
LocalDate isoDate = ... ThaiBuddhistDate thaiDate = ... int isoYear = isoDate.get(ChronoField.YEAR); int thaiYear = 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)
-
date(yearProleptic, month, day)
-
date(era, yearOfEra, month, day)
-
dateYearDay(yearProleptic, dayOfYear)
-
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 ofChronology
, ChronoLocalDate
and Era
.
The majority of the logic specific to the calendar system will be in the
ChronoLocalDate
implementation.
The Chronology
implementation 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 'java.time.chrono.Chronology' 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 CLDR specification then the calendar type is the concatenation of the CLDR type and, if applicable, the CLDR variant.
- Implementation Requirements:
- This interface 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
-
Method Summary
Modifier and TypeMethodDescriptionint
compareTo
(Chronology other) Compares this chronology to another chronology.date
(int prolepticYear, int month, int dayOfMonth) Obtains a local date in this chronology from the proleptic-year, month-of-year and day-of-month fields.default ChronoLocalDate
Obtains a local date in this chronology from the era, year-of-era, month-of-year and day-of-month fields.date
(TemporalAccessor temporal) Obtains a local date in this chronology from another temporal object.dateEpochDay
(long epochDay) Obtains a local date in this chronology from the epoch-day.default ChronoLocalDate
dateNow()
Obtains the current local date in this chronology from the system clock in the default time-zone.default ChronoLocalDate
Obtains the current local date in this chronology from the specified clock.default ChronoLocalDate
Obtains the current local date in this chronology from the system clock in the specified time-zone.dateYearDay
(int prolepticYear, int dayOfYear) Obtains a local date in this chronology from the proleptic-year and day-of-year fields.default ChronoLocalDate
dateYearDay
(Era era, int yearOfEra, int dayOfYear) Obtains a local date in this chronology from the era, year-of-era and day-of-year fields.default 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.default long
epochSecond
(Era era, int yearOfEra, 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.boolean
Checks if this chronology is equal to another chronology.eraOf
(int eraValue) Creates the chronology era object from the numeric value.eras()
Gets the list of eras for the chronology.static Chronology
from
(TemporalAccessor temporal) Obtains an instance ofChronology
from a temporal object.static Set
<Chronology> Returns the available chronologies.Gets the calendar type of the calendar system.default String
getDisplayName
(TextStyle style, Locale locale) Gets the textual representation of this chronology.getId()
Gets the ID of the chronology.int
hashCode()
A hash code for this chronology.default boolean
Checks if this chronology is ISO based.boolean
isLeapYear
(long prolepticYear) Checks if the specified year is a leap year.default ChronoLocalDateTime
<? extends ChronoLocalDate> localDateTime
(TemporalAccessor temporal) Obtains a local date-time in this chronology from another temporal object.static Chronology
Obtains an instance ofChronology
from a chronology ID or calendar system type.static Chronology
Obtains an instance ofChronology
from a locale.default ChronoPeriod
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) Calculates the proleptic-year given the era and year-of-era.range
(ChronoField field) Gets the range of valid values for the specified field.resolveDate
(Map<TemporalField, Long> fieldValues, ResolverStyle resolverStyle) Resolves parsedChronoField
values into a date during parsing.toString()
Outputs this chronology as aString
.default ChronoZonedDateTime
<? extends ChronoLocalDate> zonedDateTime
(Instant instant, ZoneId zone) Obtains aChronoZonedDateTime
in this chronology from anInstant
.default ChronoZonedDateTime
<? extends ChronoLocalDate> zonedDateTime
(TemporalAccessor temporal) Obtains aChronoZonedDateTime
in this chronology from another temporal object.
-
Method Details
-
from
Obtains an instance ofChronology
from a temporal object.This obtains a chronology based on the specified temporal. A
TemporalAccessor
represents an arbitrary set of date and time information, which this factory converts to an instance ofChronology
.The conversion will obtain the chronology using
TemporalQueries.chronology()
. If the specified temporal object does not have a chronology,IsoChronology
is returned.This method matches the signature of the functional interface
TemporalQuery
allowing it to be used as a query via method reference,Chronology::from
.- Parameters:
temporal
- the temporal to convert, not null- Returns:
- the chronology, not null
- Throws:
DateTimeException
- if unable to convert to aChronology
-
ofLocale
Obtains an instance ofChronology
from a locale.This returns a
Chronology
based on the specified locale, typically returningIsoChronology
. Other calendar systems are only returned if they are explicitly selected within the locale.The
Locale
class provide access to a range of information useful for localizing an application. This includes the language and region, such as "en-GB" for English as used in Great Britain.The
Locale
class also supports an extension mechanism that can be used to identify a calendar system. The mechanism is a form of key-value pairs, where the calendar system has the key "ca". For example, the locale "en-JP-u-ca-japanese" represents the English language as used in Japan with the Japanese calendar system.This method finds the desired calendar system in a manner equivalent to passing "ca" to
Locale.getUnicodeLocaleType(String)
. If the "ca" key is not present, thenIsoChronology
is returned.Note that the behavior of this method differs from the older
Calendar.getInstance(Locale)
method. If that method receives a locale of "th_TH" it will returnBuddhistCalendar
. By contrast, this method will returnIsoChronology
. Passing the locale "th-TH-u-ca-buddhist" into either method will result in the Thai Buddhist calendar system and is therefore the recommended approach going forward for Thai calendar system localization.A similar, but simpler, situation occurs for the Japanese calendar system. The locale "jp_JP_JP" has previously been used to access the calendar. However, unlike the Thai locale, "ja_JP_JP" is automatically converted by
Locale
to the modern and recommended form of "ja-JP-u-ca-japanese". Thus, there is no difference in behavior between this method andCalendar#getInstance(Locale)
.- Parameters:
locale
- the locale to use to obtain the calendar system, not null- Returns:
- the calendar system associated with the locale, not null
- Throws:
DateTimeException
- if the locale-specified calendar cannot be found
-
of
Obtains an instance ofChronology
from a chronology ID or calendar system type.This returns a chronology based on either the ID or the type. The
chronology ID
uniquely identifies the chronology. Thecalendar system type
is defined by the CLDR specification.The chronology may be a system chronology or a chronology provided by the application via ServiceLoader configuration.
Since some calendars can be customized, the ID or type typically refers to the default customization. For example, the Gregorian calendar can have multiple cutover dates from the Julian, but the lookup only provides the default cutover date.
- Parameters:
id
- the chronology ID or calendar system type, not null- Returns:
- the chronology with the identifier requested, not null
- Throws:
DateTimeException
- if the chronology cannot be found
-
getAvailableChronologies
Returns the available chronologies.Each returned
Chronology
is available for use in the system. The set of chronologies includes the system chronologies and any chronologies provided by the application via ServiceLoader configuration.- Returns:
- the independent, modifiable set of the available chronology IDs, not null
-
getId
String getId()Gets the ID of the chronology.The ID uniquely identifies the
Chronology
. It can be used to lookup theChronology
usingof(String)
.- Returns:
- the chronology ID, not null
- See Also:
-
getCalendarType
String getCalendarType()Gets the calendar type of the calendar system.The calendar type is an identifier defined by the CLDR and Unicode Locale Data Markup Language (LDML) specifications to uniquely identify a calendar. The
getCalendarType
is the concatenation of the CLDR calendar type and the variant, if applicable, is appended separated by "-". The calendar type is used to lookup theChronology
usingof(String)
.- Returns:
- the calendar system type, null if the calendar is not defined by CLDR/LDML
- See Also:
-
date
Obtains a local date in this chronology from the era, year-of-era, month-of-year and day-of-month fields.- Implementation Requirements:
- The default implementation combines the era and year-of-era into a proleptic
year before calling
date(int, int, int)
. - Parameters:
era
- the era of the correct type for the chronology, not nullyearOfEra
- the chronology year-of-eramonth
- the chronology month-of-yeardayOfMonth
- the chronology day-of-month- Returns:
- the local date in this chronology, not null
- Throws:
DateTimeException
- if unable to create the dateClassCastException
- if theera
is not of the correct type for the chronology
-
date
Obtains a local date in this chronology from the proleptic-year, month-of-year and day-of-month fields.- Parameters:
prolepticYear
- the chronology proleptic-yearmonth
- the chronology month-of-yeardayOfMonth
- the chronology day-of-month- Returns:
- the local date in this chronology, not null
- Throws:
DateTimeException
- if unable to create the date
-
dateYearDay
Obtains a local date in this chronology from the era, year-of-era and day-of-year fields.- Implementation Requirements:
- The default implementation combines the era and year-of-era into a proleptic
year before calling
dateYearDay(int, int)
. - Parameters:
era
- the era of the correct type for the chronology, not nullyearOfEra
- the chronology year-of-eradayOfYear
- the chronology day-of-year- Returns:
- the local date in this chronology, not null
- Throws:
DateTimeException
- if unable to create the dateClassCastException
- if theera
is not of the correct type for the chronology
-
dateYearDay
Obtains a local date in this chronology from the proleptic-year and day-of-year fields.- Parameters:
prolepticYear
- the chronology proleptic-yeardayOfYear
- the chronology day-of-year- Returns:
- the local date in this chronology, not null
- Throws:
DateTimeException
- if unable to create the date
-
dateEpochDay
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.- Parameters:
epochDay
- the epoch day- Returns:
- the local date in this chronology, not null
- Throws:
DateTimeException
- if unable to create the date
-
dateNow
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.
- Implementation Requirements:
- The default implementation invokes
dateNow(Clock)
. - Returns:
- the current local date using the system clock and default time-zone, not null
- Throws:
DateTimeException
- if unable to create the date
-
dateNow
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.
- Implementation Requirements:
- The default implementation invokes
dateNow(Clock)
. - Parameters:
zone
- the zone ID to use, not null- Returns:
- the current local date using the system clock, not null
- Throws:
DateTimeException
- if unable to create the date
-
dateNow
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
.- Implementation Requirements:
- The default implementation invokes
date(TemporalAccessor)
. - Parameters:
clock
- the clock to use, not null- Returns:
- the current local date, not null
- Throws:
DateTimeException
- if unable to create the date
-
date
Obtains a local date in this chronology from another temporal object.This obtains a date in this chronology based on the specified temporal. A
TemporalAccessor
represents an arbitrary set of date and time information, which this factory converts to an instance ofChronoLocalDate
.The conversion typically uses the
EPOCH_DAY
field, which is standardized across calendar systems.This method matches the signature of the functional interface
TemporalQuery
allowing it to be used as a query via method reference,aChronology::date
.- Parameters:
temporal
- the temporal object to convert, not null- Returns:
- the local date in this chronology, not null
- Throws:
DateTimeException
- if unable to create the date- See Also:
-
localDateTime
Obtains a local date-time in this chronology from another temporal object.This obtains a date-time in this chronology based on the specified temporal. A
TemporalAccessor
represents an arbitrary set of date and time information, which this factory converts to an instance ofChronoLocalDateTime
.The conversion extracts and combines the
ChronoLocalDate
and theLocalTime
from the temporal object. Implementations are permitted to perform optimizations such as accessing those fields that are equivalent to the relevant objects. The result uses this chronology.This method matches the signature of the functional interface
TemporalQuery
allowing it to be used as a query via method reference,aChronology::localDateTime
.- Parameters:
temporal
- the temporal object to convert, not null- Returns:
- the local date-time in this chronology, not null
- Throws:
DateTimeException
- if unable to create the date-time- See Also:
-
zonedDateTime
Obtains aChronoZonedDateTime
in this chronology from another temporal object.This obtains a zoned date-time in this chronology based on the specified temporal. A
TemporalAccessor
represents an arbitrary set of date and time information, which this factory converts to an instance ofChronoZonedDateTime
.The conversion will first obtain a
ZoneId
from the temporal object, falling back to aZoneOffset
if necessary. It will then try to obtain anInstant
, falling back to aChronoLocalDateTime
if necessary. The result will be either the combination ofZoneId
orZoneOffset
withInstant
orChronoLocalDateTime
. Implementations are permitted to perform optimizations such as accessing those fields that are equivalent to the relevant objects. The result uses this chronology.This method matches the signature of the functional interface
TemporalQuery
allowing it to be used as a query via method reference,aChronology::zonedDateTime
.- Parameters:
temporal
- the temporal object to convert, not null- Returns:
- the zoned date-time in this chronology, not null
- Throws:
DateTimeException
- if unable to create the date-time- See Also:
-
zonedDateTime
Obtains aChronoZonedDateTime
in this chronology from anInstant
.This obtains a zoned date-time with the same instant as that specified.
- Parameters:
instant
- the instant to create the date-time from, not nullzone
- the time-zone, not null- Returns:
- the zoned date-time, not null
- Throws:
DateTimeException
- if the result exceeds the supported range
-
isLeapYear
boolean isLeapYear(long prolepticYear) 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.
- the correct result must be returned for all years within the valid range of years for the chronology.
Outside the range of valid years an implementation is free to return either a best guess or false. An implementation must not throw an exception, even if the year is outside the range of valid years.
- Parameters:
prolepticYear
- the proleptic-year to check, not validated for range- Returns:
- true if the year is a leap year
-
prolepticYear
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.- Parameters:
era
- the era of the correct type for the chronology, not nullyearOfEra
- the chronology year-of-era- Returns:
- the proleptic-year
- Throws:
DateTimeException
- if unable to convert to a proleptic-year, such as if the year is invalid for the eraClassCastException
- if theera
is not of the correct type for the chronology
-
eraOf
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.
- Parameters:
eraValue
- the era value- Returns:
- the calendar system era, not null
- Throws:
DateTimeException
- if unable to create the era
-
eras
-
range
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.
- Parameters:
field
- the field to get the range for, not null- Returns:
- the range of valid values for the field, not null
- Throws:
DateTimeException
- if the range for the field cannot be obtained
-
getDisplayName
Gets the textual representation of this chronology.This returns the textual name used to identify the chronology, suitable for presentation to the user. The parameters control the style of the returned text and the locale.
- Implementation Requirements:
- The default implementation behaves as though the formatter was used to format the chronology textual name.
- Parameters:
style
- the style of the text required, not nulllocale
- the locale to use, not null- Returns:
- the text value of the chronology, not null
-
resolveDate
Resolves parsedChronoField
values into a date during parsing.Most
TemporalField
implementations are resolved using the resolve method on the field. By contrast, theChronoField
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
.- Parameters:
fieldValues
- the map of fields to values, which can be updated, not nullresolverStyle
- 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
-
period
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.- Implementation Requirements:
- 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.
- Parameters:
years
- the number of years, may be negativemonths
- the number of years, may be negativedays
- the number of years, may be negative- Returns:
- the period in terms of this chronology, not null
-
epochSecond
default 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 proleptic-year, month, day-of-month, hour, minute, second, and zoneOffset.
- Parameters:
prolepticYear
- the chronology proleptic-yearmonth
- the chronology month-of-yeardayOfMonth
- the chronology day-of-monthhour
- the hour-of-day, from 0 to 23minute
- the minute-of-hour, from 0 to 59second
- the second-of-minute, from 0 to 59zoneOffset
- the zone offset, not null- Returns:
- the number of seconds relative to 1970-01-01T00:00:00Z, may be negative
- Throws:
DateTimeException
- if any of the values are out of range- Since:
- 9
-
epochSecond
default long epochSecond(Era era, int yearOfEra, 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 era, year-of-era, month, day-of-month, hour, minute, second, and zoneOffset.
- Parameters:
era
- the era of the correct type for the chronology, not nullyearOfEra
- the chronology year-of-eramonth
- the chronology month-of-yeardayOfMonth
- the chronology day-of-monthhour
- the hour-of-day, from 0 to 23minute
- the minute-of-hour, from 0 to 59second
- the second-of-minute, from 0 to 59zoneOffset
- the zone offset, not null- Returns:
- the number of seconds relative to 1970-01-01T00:00:00Z, may be negative
- Throws:
DateTimeException
- if any of the values are out of range- Since:
- 9
-
isIsoBased
default boolean isIsoBased()Checks if this chronology is ISO based.An ISO based chronology has the same basic structure as the
ISO chronology
, i.e., the chronology has the same number of months, the number of days in each month, and day-of-year and leap years are the same as ISO chronology. It also supports the concept of week-based-year of ISO chronology. For example, theMinguo
,ThaiThaiBuddhist
andJapanese
chronologies are ISO based.- Implementation Requirements:
- The default implementation returns
false
. - Returns:
true
only if all the fields ofIsoFields
are supported by this chronology. Otherwise, returnsfalse
.- Since:
- 19
- See Also:
-
compareTo
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 interfaceComparable<Chronology>
- Parameters:
other
- the other chronology to compare to, not null- Returns:
- the comparator value, that is this ID string compared with the
other
's ID string unless the ID strings are equal and the chronology distinguishes instances using additional information
-
equals
Checks if this chronology is equal to another chronology.The comparison is based on the entire state of the object.
-
hashCode
-
toString
-