* 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 available * for use by any {@code 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 * {@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. *
* *
* 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 '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, * *
* The initialization is done only once using the registration
* of the IsoChronology as the test and the final step.
* Multiple threads may perform the initialization concurrently.
* Only the first registration of each Chronology is retained by the
* ConcurrentHashMap.
* @return true if the cache was initialized
*/
private static boolean initCache() {
if (CHRONOS_BY_ID.get("ISO") == null) {
// Initialization is incomplete
// Register built-in Chronologies
registerChrono(HijrahChronology.INSTANCE);
registerChrono(JapaneseChronology.INSTANCE);
registerChrono(MinguoChronology.INSTANCE);
registerChrono(ThaiBuddhistChronology.INSTANCE);
// Register Chronologies from the ServiceLoader
@SuppressWarnings("rawtypes")
ServiceLoader
* This obtains a chronology based on the specified temporal.
* A {@code TemporalAccessor} represents an arbitrary set of date and time information,
* which this factory converts to an instance of {@code Chronology}.
*
* The conversion will obtain the chronology using {@link TemporalQuery#chronology()}.
* If the specified temporal object does not have a chronology, {@link IsoChronology} is returned.
*
* This method matches the signature of the functional interface {@link TemporalQuery}
* allowing it to be used in queries via method reference, {@code Chronology::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) {
Objects.requireNonNull(temporal, "temporal");
Chronology obj = temporal.query(TemporalQuery.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"
* and an optional variant key "cv".
* 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.
* The variant, if present, is appended to the "ca" value separated by "-"
* and the concatenated value is used to find the calendar system by type.
*
* 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) {
Objects.requireNonNull(locale, "locale");
String type = locale.getUnicodeLocaleType("ca");
if (type == null || "iso".equals(type) || "iso8601".equals(type)) {
return IsoChronology.INSTANCE;
}
String variant = locale.getUnicodeLocaleType("cv");
if (variant != null && !variant.isEmpty()) {
type = type + '-' + variant;
}
// Not pre-defined; lookup by the type
do {
Chronology chrono = CHRONOS_BY_TYPE.get(type);
if (chrono != null) {
return chrono;
}
// If not found, do the initialization (once) and repeat the lookup
} while (initCache());
// Look for a Chronology using ServiceLoader of the Thread's ContextClassLoader
// Application provided Chronologies must not be cached
@SuppressWarnings("rawtypes")
ServiceLoader
* 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
* 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.
*
* @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) {
Objects.requireNonNull(id, "id");
do {
Chronology chrono = of0(id);
if (chrono != null) {
return chrono;
}
// If not found, do the initialization (once) and repeat the lookup
} while (initCache());
// Look for a Chronology using ServiceLoader of the Thread's ContextClassLoader
// Application provided Chronologies must not be cached
@SuppressWarnings("rawtypes")
ServiceLoader
* Each returned {@code 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.
*
* @return the independent, modifiable set of the available chronology IDs, not null
*/
public static Set
* 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 calendar system.
*
* The calendar type is an identifier defined by the CLDR and
* Unicode Locale Data Markup Language (LDML) specifications
* to uniquely identification a calendar.
* The {@code 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 {@code Chronology} using {@link #of(String)}.
*
* @return the calendar system type, null if the calendar is not defined
* @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 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) {
Objects.requireNonNull(clock, "clock");
return date(LocalDate.now(clock));
}
//-----------------------------------------------------------------------
/**
* Obtains a local date in this chronology from another temporal object.
*
* This obtains a date in this chronology based on the specified temporal.
* A {@code TemporalAccessor} represents an arbitrary set of date and time information,
* which this factory converts to an instance of {@code ChronoLocalDate}.
*
* The conversion typically uses the {@link ChronoField#EPOCH_DAY EPOCH_DAY}
* field, which is standardized across calendar systems.
*
* This method matches the signature of the functional interface {@link TemporalQuery}
* allowing it to be used as a query via method reference, {@code aChronology::date}.
*
* @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
* @see ChronoLocalDate#from(TemporalAccessor)
*/
public abstract ChronoLocalDate date(TemporalAccessor temporal);
/**
* 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 {@code TemporalAccessor} represents an arbitrary set of date and time information,
* which this factory converts to an instance of {@code ChronoLocalDateTime}.
*
* The conversion extracts and combines the {@code ChronoLocalDate} and the
* {@code 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 {@link TemporalQuery}
* allowing it to be used as a query via method reference, {@code aChronology::localDateTime}.
*
* @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
* @see ChronoLocalDateTime#from(TemporalAccessor)
*/
public ChronoLocalDateTime localDateTime(TemporalAccessor temporal) {
try {
return date(temporal).atTime(LocalTime.from(temporal));
} catch (DateTimeException ex) {
throw new DateTimeException("Unable to obtain ChronoLocalDateTime from TemporalAccessor: " + temporal.getClass(), ex);
}
}
/**
* Obtains a {@code ChronoZonedDateTime} in this chronology from another temporal object.
*
* This obtains a zoned date-time in this chronology based on the specified temporal.
* A {@code TemporalAccessor} represents an arbitrary set of date and time information,
* which this factory converts to an instance of {@code ChronoZonedDateTime}.
*
* The conversion will first obtain a {@code ZoneId} from the temporal object,
* falling back to a {@code ZoneOffset} if necessary. It will then try to obtain
* an {@code Instant}, falling back to a {@code ChronoLocalDateTime} if necessary.
* The result will be either the combination of {@code ZoneId} or {@code ZoneOffset}
* with {@code Instant} or {@code 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 {@link TemporalQuery}
* allowing it to be used as a query via method reference, {@code aChronology::zonedDateTime}.
*
* @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
* @see ChronoZonedDateTime#from(TemporalAccessor)
*/
public ChronoZonedDateTime zonedDateTime(TemporalAccessor temporal) {
try {
ZoneId zone = ZoneId.from(temporal);
try {
Instant instant = Instant.from(temporal);
return zonedDateTime(instant, zone);
} catch (DateTimeException ex1) {
@SuppressWarnings("rawtypes")
ChronoLocalDateTimeImpl cldt = ensureChronoLocalDateTime(localDateTime(temporal));
return ChronoZonedDateTimeImpl.ofBest(cldt, zone, null);
}
} catch (DateTimeException ex) {
throw new DateTimeException("Unable to obtain ChronoZonedDateTime from TemporalAccessor: " + temporal.getClass(), ex);
}
}
/**
* Obtains a {@code ChronoZonedDateTime} in this chronology from an {@code Instant}.
*
* This obtains 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) {
return ChronoZonedDateTimeImpl.ofInstant(this, instant, zone);
}
//-----------------------------------------------------------------------
/**
* 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.
*
*
* @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.
*
* If the chronology makes active use of eras, such as {@code JapaneseChronology}
* then the year-of-era will be validated against the era.
* For other chronologies, validation is optional.
*
* @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 to a proleptic-year,
* such as if the year is invalid for the era
* @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
* 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,
* suitable for presentation to the user.
* 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(toTemporal());
}
/**
* Converts this chronology to a {@code TemporalAccessor}.
*
* A {@code Chronology} can be fully represented as a {@code TemporalAccessor}.
* However, the interface is not implemented by this class as most of the
* methods on the interface have no meaning to {@code Chronology}.
*
* The returned temporal has no supported fields, with the query method
* supporting the return of the chronology using {@link TemporalQuery#chronology()}.
*
* @return a temporal equivalent to this chronology, not null
*/
private TemporalAccessor toTemporal() {
return new TemporalAccessor() {
@Override
public boolean isSupported(TemporalField field) {
return false;
}
@Override
public long getLong(TemporalField field) {
throw new UnsupportedTemporalTypeException("Unsupported field: " + field);
}
@SuppressWarnings("unchecked")
@Override
public
* 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 is suitable for most calendar systems.
* If {@link ChronoField#YEAR_OF_ERA} is found without an {@link ChronoField#ERA}
* then the last era in {@link #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.
*
* @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 ChronoLocalDate resolveDate(Map
* If the field is not already present, then the field-value pair is added to the map.
* If the field is already present and it has the same value as that specified, no action occurs.
* If the field is already present and it has a different value to that specified, then
* an exception is thrown.
*
* @param field the field to add, not null
* @param value the value to add, not null
* @throws DateTimeException if the field is already present with a different value
*/
void addFieldValue(Map
* 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();
}
//-----------------------------------------------------------------------
/**
* Writes the Chronology using a
* dedicated serialized form.
*
*
* out.writeByte(1); // identifies this as a Chronology
* out.writeUTF(getId());
*
*
* @return the instance of {@code Ser}, not null
*/
protected 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);
}
}