Class Chronology
- java.lang.Object
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- org.threeten.bp.chrono.Chronology
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- All Implemented Interfaces:
Comparable<Chronology>
- Direct Known Subclasses:
AbstractChronology
,HijrahChronology
,IsoChronology
,JapaneseChronology
,MinguoChronology
,ThaiBuddhistChronology
public abstract class Chronology extends Object implements Comparable<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 anyChronology
implementation:LocalDate isoDate = ... ChronoLocalDate<ThaiBuddhistChrono> minguoDate = ... 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 differentChronology
instances, both can be queried using the same constant onChronoField
. For a full discussion of the implications of this, seeChronoLocalDate
. In general, the advice is to use the known ISO-basedLocalDate
, rather thanChronoLocalDate
.While a
Chronology
object typically usesChronoField
and is based on an era, year-of-era, month-of-year, day-of-month model of a date, this is not required. AChronology
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. Theof(String)
method allows an instance to be looked up by identifier, while theofLocale(Locale)
method allows lookup by locale.The
Chronology
instance provides a set of methods to createChronoLocalDate
instances. The date classes are used to manipulate specific dates.-
dateNow()
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dateNow(clock)
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dateNow(zone)
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date(yearProleptic, month, day)
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date(era, yearOfEra, month, day)
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dateYearDay(yearProleptic, dayOfYear)
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dateYearDay(era, yearOfEra, dayOfYear)
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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
andEra
. The majority of the logic specific to the calendar system will be inChronoLocalDate
. TheChronology
subclass acts as a factory.To permit the discovery of additional chronologies, the
ServiceLoader
is used. A file must be added to theMETA-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.In JDK 8, this is an interface with default methods. Since there are no default methods in JDK 7, an abstract class is used.
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Field Summary
Fields Modifier and Type Field Description static TemporalQuery<Chronology>
FROM
Simulate JDK 8 method reference Chronology::from.
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Constructor Summary
Constructors Modifier Constructor Description protected
Chronology()
Creates an instance.
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description int
compareTo(Chronology other)
Compares this chronology to another chronology.abstract ChronoLocalDate
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.ChronoLocalDate
date(Era era, int yearOfEra, int month, int dayOfMonth)
Obtains a local date in this chronology from the era, year-of-era, month-of-year and day-of-month fields.abstract ChronoLocalDate
date(TemporalAccessor temporal)
Obtains a local date in this chronology from another temporal object.abstract ChronoLocalDate
dateEpochDay(long epochDay)
Obtains a local date in this chronology from the epoch-day.ChronoLocalDate
dateNow()
Obtains the current local date in this chronology from the system clock in the default time-zone.ChronoLocalDate
dateNow(Clock clock)
Obtains the current local date in this chronology from the specified clock.ChronoLocalDate
dateNow(ZoneId zone)
Obtains the current local date in this chronology from the system clock in the specified time-zone.abstract ChronoLocalDate
dateYearDay(int prolepticYear, int dayOfYear)
Obtains a local date in this chronology from the proleptic-year and day-of-year fields.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.boolean
equals(Object obj)
Checks if this chronology is equal to another chronology.abstract Era
eraOf(int eraValue)
Creates the chronology era object from the numeric value.abstract List<Era>
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>
getAvailableChronologies()
Returns the available chronologies.abstract String
getCalendarType()
Gets the calendar type of the underlying calendar system.String
getDisplayName(TextStyle style, Locale locale)
Gets the textual representation of this chronology.abstract String
getId()
Gets the ID of the chronology.int
hashCode()
A hash code for this chronology.abstract boolean
isLeapYear(long prolepticYear)
Checks if the specified year is a leap year.ChronoLocalDateTime<?>
localDateTime(TemporalAccessor temporal)
Obtains a local date-time in this chronology from another temporal object.static Chronology
of(String id)
Obtains an instance ofChronology
from a chronology ID or calendar system type.static Chronology
ofLocale(Locale locale)
Obtains an instance ofChronology
from a locale.ChronoPeriod
period(int years, int months, int days)
Obtains a period for this chronology based on years, months and days.abstract int
prolepticYear(Era era, int yearOfEra)
Calculates the proleptic-year given the era and year-of-era.abstract ValueRange
range(ChronoField field)
Gets the range of valid values for the specified field.abstract ChronoLocalDate
resolveDate(Map<TemporalField,Long> fieldValues, ResolverStyle resolverStyle)
Resolves parsedChronoField
values into a date during parsing.String
toString()
Outputs this chronology as aString
, using the ID.ChronoZonedDateTime<?>
zonedDateTime(Instant instant, ZoneId zone)
Obtains a zoned date-time in this chronology from anInstant
.ChronoZonedDateTime<?>
zonedDateTime(TemporalAccessor temporal)
Obtains a zoned date-time in this chronology from another temporal object.
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Field Detail
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FROM
public static final TemporalQuery<Chronology> FROM
Simulate JDK 8 method reference Chronology::from.
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Method Detail
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from
public static Chronology from(TemporalAccessor temporal)
Obtains an instance ofChronology
from a temporal object.A
TemporalAccessor
represents some form of date and time information. This factory converts the arbitrary temporal object to an instance ofChronology
. If the specified temporal object does not have a chronology,IsoChronology
is returned.The conversion will obtain the chronology using
TemporalQueries.chronology()
.This method matches the signature of the functional interface
TemporalQuery
allowing it to be used in queries via method reference,Chrono::from
.- Parameters:
temporal
- the temporal to convert, not null- Returns:
- the chronology, not null
- Throws:
DateTimeException
- if unable to convert to anChronology
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ofLocale
public static Chronology ofLocale(Locale locale)
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 by 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
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of
public static Chronology of(String id)
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 LDML 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
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getAvailableChronologies
public static Set<Chronology> getAvailableChronologies()
Returns the available chronologies.Each returned
Chronology
is available for use in the system.- Returns:
- the independent, modifiable set of the available chronology IDs, not null
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getId
public abstract 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()
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getCalendarType
public abstract String getCalendarType()
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
usingof(String)
. It can also be used as part of a locale, accessible viaLocale#getUnicodeLocaleType(String)
with the key 'ca'.- Returns:
- the calendar system type, null if the calendar is not defined by LDML
- See Also:
getId()
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date
public ChronoLocalDate date(Era era, int yearOfEra, int month, int dayOfMonth)
Obtains a local date in this chronology from the era, year-of-era, month-of-year and day-of-month fields.- 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
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date
public abstract ChronoLocalDate 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.- 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
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dateYearDay
public 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.- 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
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dateYearDay
public abstract ChronoLocalDate dateYearDay(int prolepticYear, int dayOfYear)
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
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dateEpochDay
public abstract ChronoLocalDate dateEpochDay(long epochDay)
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
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date
public abstract ChronoLocalDate date(TemporalAccessor temporal)
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.- 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
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dateNow
public ChronoLocalDate 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.
This implementation uses
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
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dateNow
public ChronoLocalDate dateNow(ZoneId 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.
- 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
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dateNow
public ChronoLocalDate dateNow(Clock 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
.- Parameters:
clock
- the clock to use, not null- Returns:
- the current local date, not null
- Throws:
DateTimeException
- if unable to create the date
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localDateTime
public ChronoLocalDateTime<?> localDateTime(TemporalAccessor temporal)
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 thenano-of-day
field.- 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
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zonedDateTime
public ChronoZonedDateTime<?> zonedDateTime(TemporalAccessor temporal)
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
usingZoneId.from(TemporalAccessor)
. The date-time should be obtained by obtaining anInstant
. If that fails, the local date-time should be used.- 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
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zonedDateTime
public ChronoZonedDateTime<?> zonedDateTime(Instant instant, ZoneId zone)
Obtains a zoned date-time in this chronology from anInstant
.This creates 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
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period
public ChronoPeriod 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 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.
- 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
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isLeapYear
public abstract 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.
- Parameters:
prolepticYear
- the proleptic-year to check, not validated for range- Returns:
- true if the year is a leap year
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prolepticYear
public abstract int prolepticYear(Era era, int yearOfEra)
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.
- 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 convertClassCastException
- if theera
is not of the correct type for the chronology
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eraOf
public abstract Era eraOf(int eraValue)
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
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eras
public abstract List<Era> eras()
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
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range
public abstract ValueRange range(ChronoField 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.
- 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
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getDisplayName
public String getDisplayName(TextStyle style, Locale locale)
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.
- 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
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resolveDate
public abstract ChronoLocalDate resolveDate(Map<TemporalField,Long> fieldValues, ResolverStyle resolverStyle)
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
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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
.The default implementation compares the chronology ID. Subclasses must compare any additional state that they store.
- Specified by:
compareTo
in interfaceComparable<Chronology>
- Parameters:
other
- the other chronology to compare to, not null- Returns:
- the comparator value, negative if less, positive if greater
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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.
The default implementation checks the type and calls
compareTo(Chronology)
.
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hashCode
public int hashCode()
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.
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