public final class JapaneseDate extends Object implements ChronoLocalDate, Serializable
A date in the Japanese Imperial calendar system.
This date operates using the Japanese Imperial calendar. This calendar system is primarily used in Japan.
The Japanese Imperial calendar system is the same as the ISO calendar system apart from the era-based year numbering. The proleptic-year is defined to be equal to the ISO proleptic-year.
Japan introduced the Gregorian calendar starting with Meiji 6. Only Meiji and later eras are supported; dates before Meiji 6, January 1 are not supported.
For example, the Japanese year "Heisei 24" corresponds to ISO year "2012".
Calling japaneseDate.get(YEAR_OF_ERA)
will return 24.
Calling japaneseDate.get(YEAR)
will return 2012.
Calling japaneseDate.get(ERA)
will return 2, corresponding to JapaneseChronology.ERA_HEISEI
.
This is a value-based class; use of identity-sensitive operations (including reference equality (==
), identity hash code, or synchronization) on instances of JapaneseDate
may have unpredictable results and should be avoided. The equals
method should be used for comparisons.
public static JapaneseDate now()
Obtains the current JapaneseDate
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.
public static JapaneseDate now(ZoneId zone)
Obtains the current JapaneseDate
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.
zone
- the zone ID to use, not nullpublic static JapaneseDate now(Clock clock)
Obtains the current JapaneseDate
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.
clock
- the clock to use, not nullDateTimeException
- if the current date cannot be obtainedpublic static JapaneseDate of(JapaneseEra era, int yearOfEra, int month, int dayOfMonth)
Obtains a JapaneseDate
representing a date in the Japanese calendar system from the era, year-of-era, month-of-year and day-of-month fields.
This returns a JapaneseDate
with the specified fields. The day must be valid for the year and month, otherwise an exception will be thrown.
The Japanese month and day-of-month are the same as those in the ISO calendar system. They are not reset when the era changes. For example:
6th Jan Showa 64 = ISO 1989-01-06 7th Jan Showa 64 = ISO 1989-01-07 8th Jan Heisei 1 = ISO 1989-01-08 9th Jan Heisei 1 = ISO 1989-01-09
era
- the Japanese era, not nullyearOfEra
- the Japanese year-of-eramonth
- the Japanese month-of-year, from 1 to 12dayOfMonth
- the Japanese day-of-month, from 1 to 31DateTimeException
- if the value of any field is out of range, or if the day-of-month is invalid for the month-year, or if the date is not a Japanese erapublic static JapaneseDate of(int prolepticYear, int month, int dayOfMonth)
Obtains a JapaneseDate
representing a date in the Japanese calendar system from the proleptic-year, month-of-year and day-of-month fields.
This returns a JapaneseDate
with the specified fields. The day must be valid for the year and month, otherwise an exception will be thrown.
The Japanese proleptic year, month and day-of-month are the same as those in the ISO calendar system. They are not reset when the era changes.
prolepticYear
- the Japanese proleptic-yearmonth
- the Japanese month-of-year, from 1 to 12dayOfMonth
- the Japanese day-of-month, from 1 to 31DateTimeException
- if the value of any field is out of range, or if the day-of-month is invalid for the month-yearpublic static JapaneseDate from(TemporalAccessor temporal)
Obtains a JapaneseDate
from a temporal object.
This obtains a date in the Japanese calendar system based on the specified temporal. A TemporalAccessor
represents an arbitrary set of date and time information, which this factory converts to an instance of JapaneseDate
.
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, JapaneseDate::from
.
from
in interface ChronoLocalDate
temporal
- the temporal object to convert, not nullDateTimeException
- if unable to convert to a JapaneseDate
Chronology.date(TemporalAccessor)
public JapaneseChronology getChronology()
Gets the chronology of this date, which is the Japanese calendar system.
The Chronology
represents the calendar system in use. The era and other fields in ChronoField
are defined by the chronology.
getChronology
in interface ChronoLocalDate
public JapaneseEra getEra()
Gets the era applicable at this date.
The Japanese calendar system has multiple eras defined by JapaneseEra
.
getEra
in interface ChronoLocalDate
public int lengthOfMonth()
Returns the length of the month represented by this date.
This returns the length of the month in days. Month lengths match those of the ISO calendar system.
lengthOfMonth
in interface ChronoLocalDate
public int lengthOfYear()
Description copied from interface: ChronoLocalDate
Returns the length of the year represented by this date, as defined by the calendar system.
This returns the length of the year in days.
The default implementation uses ChronoLocalDate.isLeapYear()
and returns 365 or 366.
lengthOfYear
in interface ChronoLocalDate
public boolean isSupported(TemporalField field)
Checks if the specified field is supported.
This checks if this date can be queried for the specified field. If false, then calling the range
and get
methods will throw an exception.
If the field is a ChronoField
then the query is implemented here. The supported fields are:
DAY_OF_WEEK
DAY_OF_MONTH
DAY_OF_YEAR
EPOCH_DAY
MONTH_OF_YEAR
PROLEPTIC_MONTH
YEAR_OF_ERA
YEAR
ERA
ChronoField
instances will return false. If the field is not a ChronoField
, then the result of this method is obtained by invoking TemporalField.isSupportedBy(TemporalAccessor)
passing this
as the argument. Whether the field is supported is determined by the field.
isSupported
in interface ChronoLocalDate
isSupported
in interface TemporalAccessor
field
- the field to check, null returns falsepublic ValueRange range(TemporalField field)
Description copied from interface: TemporalAccessor
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. The value of this temporal object is used to enhance the accuracy of the returned range. If the date-time cannot return the range, because the field is unsupported or for some other reason, an exception will be thrown.
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.
range
in interface TemporalAccessor
field
- the field to query the range for, not nullpublic long getLong(TemporalField field)
Description copied from interface: TemporalAccessor
Gets the value of the specified field as a long
.
This queries the date-time for the value of the specified field. The returned value may be outside the valid range of values for the field. If the date-time cannot return the value, because the field is unsupported or for some other reason, an exception will be thrown.
getLong
in interface TemporalAccessor
field
- the field to get, not nullpublic JapaneseDate with(TemporalField field, long newValue)
Description copied from interface: ChronoLocalDate
Returns an object of the same type as this object with the specified field altered.
This returns a new object based on this one with the value for the specified field changed. For example, on a LocalDate
, this could be used to set the year, month or day-of-month. The returned object will have the same observable type as this object.
In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st January, then changing the month to February would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February in this example.
with
in interface ChronoLocalDate
with
in interface Temporal
field
- the field to set in the result, not nullnewValue
- the new value of the field in the resultpublic JapaneseDate with(TemporalAdjuster adjuster)
Returns an adjusted object of the same type as this object with the adjustment made.
This adjusts this date-time according to the rules of the specified adjuster. A simple adjuster might simply set the one of the fields, such as the year field. A more complex adjuster might set the date to the last day of the month. A selection of common adjustments is provided in TemporalAdjusters
. These include finding the "last day of the month" and "next Wednesday". The adjuster is responsible for handling special cases, such as the varying lengths of month and leap years.
Some example code indicating how and why this method is used:
date = date.with(Month.JULY); // most key classes implement TemporalAdjuster date = date.with(lastDayOfMonth()); // static import from Adjusters date = date.with(next(WEDNESDAY)); // static import from Adjusters and DayOfWeek
with
in interface ChronoLocalDate
with
in interface Temporal
adjuster
- the adjuster to use, not nullDateTimeException
- if unable to make the adjustmentArithmeticException
- if numeric overflow occurspublic JapaneseDate plus(TemporalAmount amount)
Returns an object of the same type as this object with an amount added.
This adjusts this temporal, adding according to the rules of the specified amount. The amount is typically a Period
but may be any other type implementing the TemporalAmount
interface, such as Duration
.
Some example code indicating how and why this method is used:
date = date.plus(period); // add a Period instance date = date.plus(duration); // add a Duration instance date = date.plus(workingDays(6)); // example user-written workingDays method
Note that calling plus
followed by minus
is not guaranteed to return the same date-time.
plus
in interface ChronoLocalDate
plus
in interface Temporal
amount
- the amount to add, not nullDateTimeException
- if the addition cannot be madeArithmeticException
- if numeric overflow occurspublic JapaneseDate minus(TemporalAmount amount)
Returns an object of the same type as this object with an amount subtracted.
This adjusts this temporal, subtracting according to the rules of the specified amount. The amount is typically a Period
but may be any other type implementing the TemporalAmount
interface, such as Duration
.
Some example code indicating how and why this method is used:
date = date.minus(period); // subtract a Period instance date = date.minus(duration); // subtract a Duration instance date = date.minus(workingDays(6)); // example user-written workingDays method
Note that calling plus
followed by minus
is not guaranteed to return the same date-time.
minus
in interface ChronoLocalDate
minus
in interface Temporal
amount
- the amount to subtract, not nullDateTimeException
- if the subtraction cannot be madeArithmeticException
- if numeric overflow occurspublic JapaneseDate plus(long amountToAdd, TemporalUnit unit)
Description copied from interface: ChronoLocalDate
Returns an object of the same type as this object with the specified period added.
This method returns a new object based on this one with the specified period added. For example, on a LocalDate
, this could be used to add a number of years, months or days. The returned object will have the same observable type as this object.
In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st January, then adding one month would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February in this example.
plus
in interface ChronoLocalDate
plus
in interface Temporal
amountToAdd
- the amount of the specified unit to add, may be negativeunit
- the unit of the amount to add, not nullpublic JapaneseDate minus(long amountToAdd, TemporalUnit unit)
Description copied from interface: ChronoLocalDate
Returns an object of the same type as this object with the specified period subtracted.
This method returns a new object based on this one with the specified period subtracted. For example, on a LocalDate
, this could be used to subtract a number of years, months or days. The returned object will have the same observable type as this object.
In some cases, changing a field is not fully defined. For example, if the target object is a date representing the 31st March, then subtracting one month would be unclear. In cases like this, the field is responsible for resolving the result. Typically it will choose the previous valid date, which would be the last valid day of February in this example.
minus
in interface ChronoLocalDate
minus
in interface Temporal
amountToAdd
- the amount of the specified unit to subtract, may be negativeunit
- the unit of the amount to subtract, not nullpublic final ChronoLocalDateTime<JapaneseDate> atTime(LocalTime localTime)
Description copied from interface: ChronoLocalDate
Combines this date with a time to create a ChronoLocalDateTime
.
This returns a ChronoLocalDateTime
formed from this date at the specified time. All possible combinations of date and time are valid.
atTime
in interface ChronoLocalDate
localTime
- the local time to use, not nullpublic ChronoPeriod until(ChronoLocalDate endDate)
Description copied from interface: ChronoLocalDate
Calculates the period between this date and another date as a ChronoPeriod
.
This calculates the period between two dates. All supplied chronologies calculate the period using years, months and days, however the ChronoPeriod
API allows the period to be represented using other units.
The start and end points are this
and the specified date. The result will be negative if the end is before the start. The negative sign will be the same in each of year, month and day.
The calculation is performed using the chronology of this date. If necessary, the input date will be converted to match.
This instance is immutable and unaffected by this method call.
until
in interface ChronoLocalDate
endDate
- the end date, exclusive, which may be in any chronology, not nullpublic long toEpochDay()
Description copied from interface: ChronoLocalDate
Converts this date to the Epoch Day.
The Epoch Day count
is a simple incrementing count of days where day 0 is 1970-01-01 (ISO). This definition is the same for all chronologies, enabling conversion.
This default implementation queries the EPOCH_DAY
field.
toEpochDay
in interface ChronoLocalDate
public boolean equals(Object obj)
Compares this date to another date, including the chronology.
Compares this JapaneseDate
with another ensuring that the date is the same.
Only objects of type JapaneseDate
are compared, other types return false. To compare the dates of two TemporalAccessor
instances, including dates in two different chronologies, use ChronoField.EPOCH_DAY
as a comparator.
equals
in interface ChronoLocalDate
obj
- the object to check, null returns falseObject.hashCode()
, HashMap
public int hashCode()
A hash code for this date.
hashCode
in interface ChronoLocalDate
Object.equals(java.lang.Object)
, System.identityHashCode(java.lang.Object)
public long until(Temporal endExclusive, TemporalUnit unit)
Description copied from interface: ChronoLocalDate
Calculates the amount of time until another date in terms of the specified unit.
This calculates the amount of time between two ChronoLocalDate
objects in terms of a single TemporalUnit
. The start and end points are this
and the specified date. The result will be negative if the end is before the start. The Temporal
passed to this method is converted to a ChronoLocalDate
using Chronology.date(TemporalAccessor)
. The calculation returns a whole number, representing the number of complete units between the two dates. For example, the amount in days between two dates can be calculated using startDate.until(endDate, DAYS)
.
There are two equivalent ways of using this method. The first is to invoke this method. The second is to use TemporalUnit.between(Temporal, Temporal)
:
// these two lines are equivalent amount = start.until(end, MONTHS); amount = MONTHS.between(start, end);The choice should be made based on which makes the code more readable.
The calculation is implemented in this method for ChronoUnit
. The units DAYS
, WEEKS
, MONTHS
, YEARS
, DECADES
, CENTURIES
, MILLENNIA
and ERAS
should be supported by all implementations. Other ChronoUnit
values will throw an exception.
If the unit is not a ChronoUnit
, then the result of this method is obtained by invoking TemporalUnit.between(Temporal, Temporal)
passing this
as the first argument and the converted input temporal as the second argument.
This instance is immutable and unaffected by this method call.
until
in interface ChronoLocalDate
until
in interface Temporal
endExclusive
- the end date, exclusive, which is converted to a ChronoLocalDate
in the same chronology, not nullunit
- the unit to measure the amount in, not nullpublic String toString()
Description copied from class: Object
Returns a string representation of the object. In general, the toString
method returns a string that "textually represents" this object. The result should be a concise but informative representation that is easy for a person to read. It is recommended that all subclasses override this method.
The toString
method for class Object
returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@
', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
toString
in interface ChronoLocalDate
toString
in class Object
© 1993–2017, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.