org.threeten.bp.chrono.Chronology Maven / Gradle / Ivy
Show all versions of threetenbp Show documentation
/*
* Copyright (c) 2007-present, Stephen Colebourne & Michael Nascimento Santos
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* * Neither the name of JSR-310 nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.threeten.bp.chrono;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectStreamException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.threeten.bp.Clock;
import org.threeten.bp.DateTimeException;
import org.threeten.bp.Instant;
import org.threeten.bp.LocalDate;
import org.threeten.bp.LocalTime;
import org.threeten.bp.ZoneId;
import org.threeten.bp.format.DateTimeFormatterBuilder;
import org.threeten.bp.format.ResolverStyle;
import org.threeten.bp.format.TextStyle;
import org.threeten.bp.jdk8.DefaultInterfaceTemporalAccessor;
import org.threeten.bp.jdk8.Jdk8Methods;
import org.threeten.bp.temporal.ChronoField;
import org.threeten.bp.temporal.Temporal;
import org.threeten.bp.temporal.TemporalAccessor;
import org.threeten.bp.temporal.TemporalField;
import org.threeten.bp.temporal.TemporalQueries;
import org.threeten.bp.temporal.TemporalQuery;
import org.threeten.bp.temporal.UnsupportedTemporalTypeException;
import org.threeten.bp.temporal.ValueRange;
/**
* 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 {@link ChronoField} and are availalbe
* for use by any {@code Chronology} 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 different
* {@code Chronology} instances, both can be queried using the same constant on {@code ChronoField}.
* For a full discussion of the implications of this, see {@link ChronoLocalDate}.
* In general, the advice is to use the known ISO-based {@code LocalDate}, rather than
* {@code ChronoLocalDate}.
*
* While a {@code Chronology} object typically uses {@code 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 {@code Chronology} instance may represent a totally different kind of calendar system,
* such as the Mayan.
*
* In practical terms, the {@code Chronology} instance also acts as a factory.
* The {@link #of(String)} method allows an instance to be looked up by identifier,
* while the {@link #ofLocale(Locale)} method allows lookup by locale.
*
* The {@code Chronology} instance provides a set of methods to create {@code ChronoLocalDate} instances.
* The date classes are used to manipulate specific dates.
*
* - {@link #dateNow() dateNow()}
*
- {@link #dateNow(Clock) dateNow(clock)}
*
- {@link #dateNow(ZoneId) dateNow(zone)}
*
- {@link #date(int, int, int) date(yearProleptic, month, day)}
*
- {@link #date(Era, int, int, int) date(era, yearOfEra, month, day)}
*
- {@link #dateYearDay(int, int) dateYearDay(yearProleptic, dayOfYear)}
*
- {@link #dateYearDay(Era, int, int) dateYearDay(era, yearOfEra, dayOfYear)}
*
- {@link #date(TemporalAccessor) 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
* {@code Chronology}, {@code ChronoLocalDate} and {@code Era}.
* The majority of the logic specific to the calendar system will be in
* {@code ChronoLocalDate}. The {@code Chronology} subclass acts as a factory.
*
* To permit the discovery of additional chronologies, the {@link java.util.ServiceLoader ServiceLoader}
* is used. A file must be added to the {@code 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.
*
* In JDK 8, this is an interface with default methods.
* Since there are no default methods in JDK 7, an abstract class is used.
*/
public abstract class Chronology implements Comparable {
/**
* Simulate JDK 8 method reference Chronology::from.
*/
public static final TemporalQuery FROM = new TemporalQuery() {
@Override
public Chronology queryFrom(TemporalAccessor temporal) {
return Chronology.from(temporal);
}
};
/**
* Map of available calendars by ID.
*/
private static final ConcurrentHashMap CHRONOS_BY_ID = new ConcurrentHashMap();
/**
* Map of available calendars by calendar type.
*/
private static final ConcurrentHashMap CHRONOS_BY_TYPE = new ConcurrentHashMap();
/**
* Access JDK 7 method if on JDK 7.
*/
private static final Method LOCALE_METHOD;
static {
Method method = null;
try {
method = Locale.class.getMethod("getUnicodeLocaleType", String.class);
} catch (Throwable ex) {
// ignore
}
LOCALE_METHOD = method;
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Chronology} from a temporal object.
*
* A {@code TemporalAccessor} represents some form of date and time information.
* This factory converts the arbitrary temporal object to an instance of {@code Chronology}.
* If the specified temporal object does not have a chronology, {@link IsoChronology} is returned.
*
* The conversion will obtain the chronology using {@link TemporalQueries#chronology()}.
*
* This method matches the signature of the functional interface {@link TemporalQuery}
* allowing it to be used in queries via method reference, {@code Chrono::from}.
*
* @param temporal the temporal to convert, not null
* @return the chronology, not null
* @throws DateTimeException if unable to convert to an {@code Chronology}
*/
public static Chronology from(TemporalAccessor temporal) {
Jdk8Methods.requireNonNull(temporal, "temporal");
Chronology obj = temporal.query(TemporalQueries.chronology());
return (obj != null ? obj : IsoChronology.INSTANCE);
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Chronology} from a locale.
*
* This returns a {@code Chronology} based on the specified locale,
* typically returning {@code IsoChronology}. Other calendar systems
* are only returned if they are explicitly selected within the locale.
*
* The {@link 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 {@code 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 {@link Locale#getUnicodeLocaleType(String)}.
* If the "ca" key is not present, then {@code IsoChronology} is returned.
*
* Note that the behavior of this method differs from the older
* {@link java.util.Calendar#getInstance(Locale)} method.
* If that method receives a locale of "th_TH" it will return {@code BuddhistCalendar}.
* By contrast, this method will return {@code 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
* {@code Locale} to the modern and recommended form of "ja-JP-u-ca-japanese".
* Thus, there is no difference in behavior between this method and
* {@code Calendar#getInstance(Locale)}.
*
* @param locale the locale to use to obtain the calendar system, not null
* @return the calendar system associated with the locale, not null
* @throws DateTimeException if the locale-specified calendar cannot be found
*/
public static Chronology ofLocale(Locale locale) {
init();
Jdk8Methods.requireNonNull(locale, "locale");
String type = "iso";
if (LOCALE_METHOD != null) {
// JDK 7: locale.getUnicodeLocaleType("ca");
try {
type = (String) LOCALE_METHOD.invoke(locale, "ca");
} catch (IllegalArgumentException ex) {
// ignore
} catch (IllegalAccessException ex) {
// ignore
} catch (InvocationTargetException ex) {
// ignore
}
} else if (locale.equals(JapaneseChronology.LOCALE)) {
type = "japanese";
}
if (type == null || "iso".equals(type) || "iso8601".equals(type)) {
return IsoChronology.INSTANCE;
} else {
Chronology chrono = CHRONOS_BY_TYPE.get(type);
if (chrono == null) {
throw new DateTimeException("Unknown calendar system: " + type);
}
return chrono;
}
}
//-----------------------------------------------------------------------
/**
* Obtains an instance of {@code Chronology} from a chronology ID or
* calendar system type.
*
* This returns a chronology based on either the ID or the type.
* The {@link #getId() chronology ID} uniquely identifies the chronology.
* The {@link #getCalendarType() calendar 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.
*
* @param id the chronology ID or calendar system type, not null
* @return the chronology with the identifier requested, not null
* @throws DateTimeException if the chronology cannot be found
*/
public static Chronology of(String id) {
init();
Chronology chrono = CHRONOS_BY_ID.get(id);
if (chrono != null) {
return chrono;
}
chrono = CHRONOS_BY_TYPE.get(id);
if (chrono != null) {
return chrono;
}
throw new DateTimeException("Unknown chronology: " + id);
}
/**
* Returns the available chronologies.
*
* Each returned {@code Chronology} is available for use in the system.
*
* @return the independent, modifiable set of the available chronology IDs, not null
*/
public static Set getAvailableChronologies() {
init();
return new HashSet(CHRONOS_BY_ID.values());
}
private static void init() {
if (CHRONOS_BY_ID.isEmpty()) {
register(IsoChronology.INSTANCE);
register(ThaiBuddhistChronology.INSTANCE);
register(MinguoChronology.INSTANCE);
register(JapaneseChronology.INSTANCE);
register(HijrahChronology.INSTANCE);
CHRONOS_BY_ID.putIfAbsent("Hijrah", HijrahChronology.INSTANCE);
CHRONOS_BY_TYPE.putIfAbsent("islamic", HijrahChronology.INSTANCE);
ServiceLoader loader = ServiceLoader.load(Chronology.class, Chronology.class.getClassLoader());
for (Chronology chrono : loader) {
CHRONOS_BY_ID.putIfAbsent(chrono.getId(), chrono);
String type = chrono.getCalendarType();
if (type != null) {
CHRONOS_BY_TYPE.putIfAbsent(type, chrono);
}
}
}
}
private static void register(Chronology chrono) {
CHRONOS_BY_ID.putIfAbsent(chrono.getId(), chrono);
String type = chrono.getCalendarType();
if (type != null) {
CHRONOS_BY_TYPE.putIfAbsent(type, chrono);
}
}
//-----------------------------------------------------------------------
/**
* Creates an instance.
*/
protected Chronology() {
}
//-----------------------------------------------------------------------
/**
* Casts the {@code Temporal} to {@code ChronoLocalDate} with the same chronology.
*
* @param temporal a date-time to cast, not null
* @return the date-time checked and cast to {@code ChronoLocalDate}, not null
* @throws ClassCastException if the date-time cannot be cast to ChronoLocalDate
* or the chronology is not equal this Chrono
*/
D ensureChronoLocalDate(Temporal temporal) {
@SuppressWarnings("unchecked")
D other = (D) temporal;
if (this.equals(other.getChronology()) == false) {
throw new ClassCastException("Chrono mismatch, expected: " + getId() + ", actual: " + other.getChronology().getId());
}
return other;
}
/**
* Casts the {@code Temporal} to {@code ChronoLocalDateTime} with the same chronology.
*
* @param temporal a date-time to cast, not null
* @return the date-time checked and cast to {@code ChronoLocalDateTime}, not null
* @throws ClassCastException if the date-time cannot be cast to ChronoLocalDateTimeImpl
* or the chronology is not equal this Chrono
*/
ChronoLocalDateTimeImpl ensureChronoLocalDateTime(Temporal temporal) {
@SuppressWarnings("unchecked")
ChronoLocalDateTimeImpl other = (ChronoLocalDateTimeImpl) temporal;
if (this.equals(other.toLocalDate().getChronology()) == false) {
throw new ClassCastException("Chrono mismatch, required: " + getId()
+ ", supplied: " + other.toLocalDate().getChronology().getId());
}
return other;
}
/**
* Casts the {@code Temporal} to {@code ChronoZonedDateTimeImpl} with the same chronology.
*
* @param temporal a date-time to cast, not null
* @return the date-time checked and cast to {@code ChronoZonedDateTimeImpl}, not null
* @throws ClassCastException if the date-time cannot be cast to ChronoZonedDateTimeImpl
* or the chronology is not equal this Chrono
*/
ChronoZonedDateTimeImpl ensureChronoZonedDateTime(Temporal temporal) {
@SuppressWarnings("unchecked")
ChronoZonedDateTimeImpl other = (ChronoZonedDateTimeImpl) temporal;
if (this.equals(other.toLocalDate().getChronology()) == false) {
throw new ClassCastException("Chrono mismatch, required: " + getId()
+ ", supplied: " + other.toLocalDate().getChronology().getId());
}
return other;
}
//-----------------------------------------------------------------------
/**
* Gets the ID of the chronology.
*
* The ID uniquely identifies the {@code Chronology}.
* It can be used to lookup the {@code Chronology} using {@link #of(String)}.
*
* @return the chronology ID, not null
* @see #getCalendarType()
*/
public abstract String getId();
/**
* 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 {@code Chronology} using {@link #of(String)}.
* It can also be used as part of a locale, accessible via
* {@link Locale#getUnicodeLocaleType(String)} with the key 'ca'.
*
* @return the calendar system type, null if the calendar is not defined by LDML
* @see #getId()
*/
public abstract String getCalendarType();
//-----------------------------------------------------------------------
/**
* Obtains a local date in this chronology from the era, year-of-era,
* month-of-year and day-of-month fields.
*
* @param era the era of the correct type for the chronology, not null
* @param yearOfEra the chronology year-of-era
* @param month the chronology month-of-year
* @param dayOfMonth the chronology day-of-month
* @return the local date in this chronology, not null
* @throws DateTimeException if unable to create the date
* @throws ClassCastException if the {@code era} is not of the correct type for the chronology
*/
public ChronoLocalDate date(Era era, int yearOfEra, int month, int dayOfMonth) {
return date(prolepticYear(era, yearOfEra), month, dayOfMonth);
}
/**
* Obtains a local date in this chronology from the proleptic-year,
* month-of-year and day-of-month fields.
*
* @param prolepticYear the chronology proleptic-year
* @param month the chronology month-of-year
* @param dayOfMonth the chronology day-of-month
* @return the local date in this chronology, not null
* @throws DateTimeException if unable to create the date
*/
public abstract ChronoLocalDate date(int prolepticYear, int month, int dayOfMonth);
/**
* Obtains a local date in this chronology from the era, year-of-era and
* day-of-year fields.
*
* @param era the era of the correct type for the chronology, not null
* @param yearOfEra the chronology year-of-era
* @param dayOfYear the chronology day-of-year
* @return the local date in this chronology, not null
* @throws DateTimeException if unable to create the date
* @throws ClassCastException if the {@code era} is not of the correct type for the chronology
*/
public ChronoLocalDate dateYearDay(Era era, int yearOfEra, int dayOfYear) {
return dateYearDay(prolepticYear(era, yearOfEra), dayOfYear);
}
/**
* Obtains a local date in this chronology from the proleptic-year and
* day-of-year fields.
*
* @param prolepticYear the chronology proleptic-year
* @param dayOfYear the chronology day-of-year
* @return the local date in this chronology, not null
* @throws DateTimeException if unable to create the date
*/
public abstract ChronoLocalDate dateYearDay(int prolepticYear, int dayOfYear);
/**
* Obtains a local date in this chronology from the epoch-day.
*
* The definition of {@link ChronoField#EPOCH_DAY EPOCH_DAY} is the same
* for all calendar systems, thus it can be used for conversion.
*
* @param epochDay the epoch day
* @return the local date in this chronology, not null
* @throws DateTimeException if unable to create the date
*/
public abstract ChronoLocalDate dateEpochDay(long epochDay);
/**
* Obtains a local date in this chronology from another temporal object.
*
* This creates a date in this chronology based on the specified {@code TemporalAccessor}.
*
* The standard mechanism for conversion between date types is the
* {@link ChronoField#EPOCH_DAY local epoch-day} field.
*
* @param temporal the temporal object to convert, not null
* @return the local date in this chronology, not null
* @throws DateTimeException if unable to create the date
*/
public abstract ChronoLocalDate date(TemporalAccessor temporal);
//-----------------------------------------------------------------------
/**
* Obtains the current local date in this chronology from the system clock in the default time-zone.
*
* This will query the {@link Clock#systemDefaultZone() 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 {@link #dateNow(Clock)}.
*
* @return the current local date using the system clock and default time-zone, not null
* @throws DateTimeException if unable to create the date
*/
public ChronoLocalDate dateNow() {
return dateNow(Clock.systemDefaultZone());
}
/**
* Obtains the current local date in this chronology from the system clock in the specified time-zone.
*
* This will query the {@link Clock#system(ZoneId) 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.
*
* @param zone the zone ID to use, not null
* @return the current local date using the system clock, not null
* @throws DateTimeException if unable to create the date
*/
public ChronoLocalDate dateNow(ZoneId zone) {
return dateNow(Clock.system(zone));
}
/**
* 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 {@link Clock dependency injection}.
*
* @param clock the clock to use, not null
* @return the current local date, not null
* @throws DateTimeException if unable to create the date
*/
public ChronoLocalDate dateNow(Clock clock) {
Jdk8Methods.requireNonNull(clock, "clock");
return date(LocalDate.now(clock));
}
//-----------------------------------------------------------------------
/**
* Obtains a local date-time in this chronology from another temporal object.
*
* This creates a date-time in this chronology based on the specified {@code TemporalAccessor}.
*
* The date of the date-time should be equivalent to that obtained by calling
* {@link #date(TemporalAccessor)}.
* The standard mechanism for conversion between time types is the
* {@link ChronoField#NANO_OF_DAY nano-of-day} field.
*
* @param temporal the temporal object to convert, not null
* @return the local date-time in this chronology, not null
* @throws DateTimeException if unable to create the date-time
*/
public ChronoLocalDateTime localDateTime(TemporalAccessor temporal) {
try {
ChronoLocalDate date = date(temporal);
return date.atTime(LocalTime.from(temporal));
} catch (DateTimeException ex) {
throw new DateTimeException("Unable to obtain ChronoLocalDateTime from TemporalAccessor: " + temporal.getClass(), ex);
}
}
/**
* Obtains a zoned date-time in this chronology from another temporal object.
*
* This creates a date-time in this chronology based on the specified {@code TemporalAccessor}.
*
* This should obtain a {@code ZoneId} using {@link ZoneId#from(TemporalAccessor)}.
* The date-time should be obtained by obtaining an {@code Instant}.
* If that fails, the local date-time should be used.
*
* @param temporal the temporal object to convert, not null
* @return the zoned date-time in this chronology, not null
* @throws DateTimeException if unable to create the date-time
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
public ChronoZonedDateTime zonedDateTime(TemporalAccessor temporal) {
try {
ZoneId zone = ZoneId.from(temporal);
try {
Instant instant = Instant.from(temporal);
return zonedDateTime(instant, zone);
} catch (DateTimeException ex1) {
ChronoLocalDateTime cldt = localDateTime(temporal);
ChronoLocalDateTimeImpl cldtImpl = ensureChronoLocalDateTime(cldt);
return ChronoZonedDateTimeImpl.ofBest(cldtImpl, zone, null);
}
} catch (DateTimeException ex) {
throw new DateTimeException("Unable to obtain ChronoZonedDateTime from TemporalAccessor: " + temporal.getClass(), ex);
}
}
/**
* Obtains a zoned date-time in this chronology from an {@code Instant}.
*
* This creates a zoned date-time with the same instant as that specified.
*
* @param instant the instant to create the date-time from, not null
* @param zone the time-zone, not null
* @return the zoned date-time, not null
* @throws DateTimeException if the result exceeds the supported range
*/
public ChronoZonedDateTime zonedDateTime(Instant instant, ZoneId zone) {
ChronoZonedDateTime result = ChronoZonedDateTimeImpl.ofInstant(this, instant, zone);
return result;
}
//-----------------------------------------------------------------------
/**
* 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 {@code 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 {@link #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 {@code ChronoPeriod} interface must be directly implemented.
*
* The returned period is immutable and thread-safe.
*
* @param years the number of years, may be negative
* @param months the number of years, may be negative
* @param days the number of years, may be negative
* @return the period in terms of this chronology, not null
*/
public ChronoPeriod period(int years, int months, int days) {
return new ChronoPeriodImpl(this, years, months, days);
}
//-----------------------------------------------------------------------
/**
* 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.
*
*
* @param prolepticYear the proleptic-year to check, not validated for range
* @return true if the year is a leap year
*/
public abstract boolean isLeapYear(long 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.
*
* @param era the era of the correct type for the chronology, not null
* @param yearOfEra the chronology year-of-era
* @return the proleptic-year
* @throws DateTimeException if unable to convert
* @throws ClassCastException if the {@code era} is not of the correct type for the chronology
*/
public abstract int prolepticYear(Era era, int yearOfEra);
/**
* 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.
*
* @param eraValue the era value
* @return the calendar system era, not null
* @throws DateTimeException if unable to create the era
*/
public abstract Era eraOf(int eraValue);
/**
* 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.
*
* @return the list of eras for the chronology, may be immutable, not null
*/
public abstract List eras();
//-----------------------------------------------------------------------
/**
* Gets the range of valid values for the specified field.
*
* All fields can be expressed as a {@code 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.
*
* @param field the field to get the range for, not null
* @return the range of valid values for the field, not null
* @throws DateTimeException if the range for the field cannot be obtained
*/
public abstract ValueRange range(ChronoField field);
//-----------------------------------------------------------------------
/**
* 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.
*
* @param style the style of the text required, not null
* @param locale the locale to use, not null
* @return the text value of the chronology, not null
*/
public String getDisplayName(TextStyle style, Locale locale) {
return new DateTimeFormatterBuilder().appendChronologyText(style).toFormatter(locale).format(new DefaultInterfaceTemporalAccessor() {
@Override
public boolean isSupported(TemporalField field) {
return false;
}
@Override
public long getLong(TemporalField field) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
@SuppressWarnings("unchecked")
@Override
public R query(TemporalQuery query) {
if (query == TemporalQueries.chronology()) {
return (R) Chronology.this;
}
return super.query(query);
}
});
}
//-----------------------------------------------------------------------
/**
* Resolves parsed {@code ChronoField} values into a date during parsing.
*
* Most {@code TemporalField} implementations are resolved using the
* resolve method on the field. By contrast, the {@code ChronoField} class
* defines fields that only have meaning relative to the chronology.
* As such, {@code ChronoField} date fields are resolved here in the
* context of a specific chronology.
*
* The default implementation, which explains typical resolve behaviour,
* is provided in {@link AbstractChronology}.
*
* @param fieldValues the map of fields to values, which can be updated, not null
* @param resolverStyle the requested type of resolve, not null
* @return 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
*/
public abstract ChronoLocalDate resolveDate(Map fieldValues, ResolverStyle resolverStyle);
/**
* Updates the map of field-values during resolution.
*
* @param field the field to update, not null
* @param value the value to update, not null
* @throws DateTimeException if a conflict occurs
*/
void updateResolveMap(Map fieldValues, ChronoField field, long value) {
Long current = fieldValues.get(field);
if (current != null && current.longValue() != value) {
throw new DateTimeException("Invalid state, field: " + field + " " + current + " conflicts with " + field + " " + value);
}
fieldValues.put(field, value);
}
//-----------------------------------------------------------------------
/**
* 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 {@link Comparable}.
*
* The default implementation compares the chronology ID.
* Subclasses must compare any additional state that they store.
*
* @param other the other chronology to compare to, not null
* @return the comparator value, negative if less, positive if greater
*/
@Override
public int compareTo(Chronology other) {
return getId().compareTo(other.getId());
}
/**
* 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 {@link #compareTo(Chronology)}.
*
* @param obj the object to check, null returns false
* @return true if this is equal to the other chronology
*/
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof Chronology) {
return compareTo((Chronology) obj) == 0;
}
return false;
}
/**
* 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.
*
* @return a suitable hash code
*/
@Override
public int hashCode() {
return getClass().hashCode() ^ getId().hashCode();
}
//-----------------------------------------------------------------------
/**
* Outputs this chronology as a {@code String}, using the ID.
*
* @return a string representation of this chronology, not null
*/
@Override
public String toString() {
return getId();
}
//-----------------------------------------------------------------------
private Object writeReplace() {
return new Ser(Ser.CHRONO_TYPE, this);
}
/**
* Defend against malicious streams.
* @return never
* @throws InvalidObjectException always
*/
private Object readResolve() throws ObjectStreamException {
throw new InvalidObjectException("Deserialization via serialization delegate");
}
void writeExternal(DataOutput out) throws IOException {
out.writeUTF(getId());
}
static Chronology readExternal(DataInput in) throws IOException {
String id = in.readUTF();
return Chronology.of(id);
}
}