Spec-Zone .ru
спецификации, руководства, описания, API
|
public abstract class Chronology extends Object implements Comparable<Chronology>
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 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)
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 '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,
Modifier | Constructor and Description |
---|---|
protected |
Chronology()
Creates an instance.
|
Modifier and Type | Method and Description |
---|---|
int |
compareTo(Chronology other)
Compares this chronology to another chronology.
|
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(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.
|
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.
|
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.
|
abstract ChronoLocalDate<?> |
dateYearDay(int prolepticYear,
int dayOfYear)
Obtains a local date in this chronology from the proleptic-year 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 of
Chronology from a temporal object. |
static Set<Chronology> |
getAvailableChronologies()
Returns the available chronologies.
|
abstract String |
getCalendarType()
Gets the calendar type of the 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 of
Chronology from a chronology ID or
calendar system type. |
static Chronology |
ofLocale(Locale locale)
Obtains an instance of
Chronology from a locale. |
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.
|
ChronoLocalDate<?> |
resolveDate(Map<TemporalField,Long> fieldValues,
ResolverStyle resolverStyle)
Resolves parsed
ChronoField values into a date during parsing. |
String |
toString()
Outputs this chronology as a
String , using the ID. |
protected Object |
writeReplace()
Writes the Chronology using a
dedicated serialized form.
|
ChronoZonedDateTime<?> |
zonedDateTime(Instant instant,
ZoneId zone)
Obtains a
ChronoZonedDateTime in this chronology from an Instant . |
ChronoZonedDateTime<?> |
zonedDateTime(TemporalAccessor temporal)
Obtains a
ChronoZonedDateTime in this chronology from another temporal object. |
public static Chronology from(TemporalAccessor temporal)
Chronology
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 of Chronology
.
The conversion will obtain the chronology using TemporalQuery.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 in queries via method reference, Chronology::from
.
temporal
- the temporal to convert, not nullDateTimeException
- if unable to convert to an Chronology
public static Chronology ofLocale(Locale locale)
Chronology
from a locale.
This returns a Chronology
based on the specified locale,
typically returning IsoChronology
. 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, then IsoChronology
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 return BuddhistCalendar
.
By contrast, this method will return IsoChronology
.
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 and
Calendar#getInstance(Locale)
.
locale
- the locale to use to obtain the calendar system, not nullDateTimeException
- if the locale-specified calendar cannot be foundpublic static Chronology of(String id)
Chronology
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.
The calendar 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.
id
- the chronology ID or calendar system type, not nullDateTimeException
- if the chronology cannot be foundpublic static Set<Chronology> getAvailableChronologies()
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.
public abstract String getId()
The ID uniquely identifies the Chronology
.
It can be used to lookup the Chronology
using of(String)
.
getCalendarType()
public abstract String getCalendarType()
The calendar type is an identifier defined by the CLDR and
Unicode Locale Data Markup Language (LDML) specifications
to uniquely identification 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 the Chronology
using of(String)
.
getId()
public ChronoLocalDate<?> date(Era era, int yearOfEra, int month, int dayOfMonth)
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-monthDateTimeException
- if unable to create the dateClassCastException
- if the era
is not of the correct type for the chronologypublic abstract ChronoLocalDate<?> date(int prolepticYear, int month, int dayOfMonth)
prolepticYear
- the chronology proleptic-yearmonth
- the chronology month-of-yeardayOfMonth
- the chronology day-of-monthDateTimeException
- if unable to create the datepublic ChronoLocalDate<?> dateYearDay(Era era, int yearOfEra, int dayOfYear)
era
- the era of the correct type for the chronology, not nullyearOfEra
- the chronology year-of-eradayOfYear
- the chronology day-of-yearDateTimeException
- if unable to create the dateClassCastException
- if the era
is not of the correct type for the chronologypublic abstract ChronoLocalDate<?> dateYearDay(int prolepticYear, int dayOfYear)
prolepticYear
- the chronology proleptic-yeardayOfYear
- the chronology day-of-yearDateTimeException
- if unable to create the datepublic abstract ChronoLocalDate<?> dateEpochDay(long epochDay)
The definition of EPOCH_DAY
is the same
for all calendar systems, thus it can be used for conversion.
epochDay
- the epoch dayDateTimeException
- if unable to create the datepublic ChronoLocalDate<?> dateNow()
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)
.
DateTimeException
- if unable to create the datepublic ChronoLocalDate<?> dateNow(ZoneId 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 nullDateTimeException
- if unable to create the datepublic ChronoLocalDate<?> dateNow(Clock 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 nullDateTimeException
- if unable to create the datepublic abstract ChronoLocalDate<?> date(TemporalAccessor temporal)
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 of ChronoLocalDate
.
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
.
temporal
- the temporal object to convert, not nullDateTimeException
- if unable to create the dateChronoLocalDate.from(TemporalAccessor)
public ChronoLocalDateTime<?> localDateTime(TemporalAccessor temporal)
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 of ChronoLocalDateTime
.
The conversion extracts and combines the ChronoLocalDate
and the
LocalTime
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
.
temporal
- the temporal object to convert, not nullDateTimeException
- if unable to create the date-timeChronoLocalDateTime.from(TemporalAccessor)
public ChronoZonedDateTime<?> zonedDateTime(TemporalAccessor temporal)
ChronoZonedDateTime
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 of ChronoZonedDateTime
.
The conversion will first obtain a ZoneId
from the temporal object,
falling back to a ZoneOffset
if necessary. It will then try to obtain
an Instant
, falling back to a ChronoLocalDateTime
if necessary.
The result will be either the combination of ZoneId
or ZoneOffset
with Instant
or ChronoLocalDateTime
.
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
.
temporal
- the temporal object to convert, not nullDateTimeException
- if unable to create the date-timeChronoZonedDateTime.from(TemporalAccessor)
public ChronoZonedDateTime<?> zonedDateTime(Instant instant, ZoneId zone)
ChronoZonedDateTime
in this chronology from an Instant
.
This obtains a zoned date-time with the same instant as that specified.
instant
- the instant to create the date-time from, not nullzone
- the time-zone, not nullDateTimeException
- if the result exceeds the supported rangepublic abstract boolean isLeapYear(long prolepticYear)
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.
prolepticYear
- the proleptic-year to check, not validated for rangepublic abstract int prolepticYear(Era era, int yearOfEra)
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.
era
- the era of the correct type for the chronology, not nullyearOfEra
- the chronology year-of-eraDateTimeException
- if unable to convert to a proleptic-year,
such as if the year is invalid for the eraClassCastException
- if the era
is not of the correct type for the chronologypublic abstract Era eraOf(int eraValue)
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 valueDateTimeException
- if unable to create the erapublic abstract List<Era> eras()
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.
public abstract ValueRange range(ChronoField 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 nullDateTimeException
- if the range for the field cannot be obtainedpublic String getDisplayName(TextStyle style, Locale locale)
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.
style
- the style of the text required, not nulllocale
- the locale to use, not nullpublic ChronoLocalDate<?> resolveDate(Map<TemporalField,Long> fieldValues, ResolverStyle resolverStyle)
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 is suitable for most calendar systems.
If ChronoField.YEAR_OF_ERA
is found without an ChronoField.ERA
then the last era in eras()
is used.
The implementation assumes a 7 day week, that the first day-of-month
has the value 1, and that first day-of-year has the value 1.
fieldValues
- the map of fields to values, which can be updated, not nullresolverStyle
- the requested type of resolve, not nullDateTimeException
- if the date cannot be resolved, typically
because of a conflict in the input datapublic int compareTo(Chronology other)
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.
compareTo
in interface Comparable<Chronology>
other
- the other chronology to compare to, not nullpublic boolean equals(Object obj)
The comparison is based on the entire state of the object.
The default implementation checks the type and calls compareTo(Chronology)
.
equals
in class Object
obj
- the object to check, null returns falseObject.hashCode()
,
HashMap
public int hashCode()
The default implementation is based on the ID and class. Subclasses should add any additional state that they store.
hashCode
in class Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
public String toString()
String
, using the ID.protected Object writeReplace()
out.writeByte(1); // identifies this as a Chronology out.writeUTF(getId());
Ser
, not null
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2013, Oracle and/or its affiliates. All rights reserved.
DRAFT ea-b92