# Class HijrahDate

java.lang.Object
java.time.chrono.HijrahDate

All Implemented Interfaces:
  `Serializable, Comparable<ChronoLocalDate>, ChronoLocalDate, Temporal, TemporalAccessor, TemporalAdjuster`

public final class HijrahDate extends Object implements ChronoLocalDate, Serializable
A date in the Hijrah calendar system.

This date operates using one of several variants of the Hijrah calendar.

The Hijrah calendar has a different total of days in a year than Gregorian calendar, and the length of each month is based on the period of a complete revolution of the moon around the earth (as between successive new moons). Refer to the `HijrahChronology` for details of supported variants.

Each HijrahDate is created bound to a particular HijrahChronology, The same chronology is propagated to each HijrahDate computed from the date. To use a different Hijrah variant, its HijrahChronology can be used to create new HijrahDate instances. Alternatively, the `withVariant(HijrahChronology)` method can be used to convert to a new HijrahChronology.

This is a value-based class; programmers should treat instances that are equal as interchangeable and should not use instances for synchronization, or unpredictable behavior may occur. For example, in a future release, synchronization may fail. The `equals` method should be used for comparisons.

Implementation Requirements:
  This class is immutable and thread-safe.
Since:
  1.8
See Also:
  - Serialized Form

- ## Method Summary

  Modifier and Type
  Method
  Description
  `final ChronoLocalDateTime<HijrahDate>`
  `atTime(LocalTime localTime)`
  Combines this date with a time to create a `ChronoLocalDateTime`.
  `boolean`
  `equals(Object obj)`
  Compares this date to another date, including the chronology.
  `static HijrahDate`
  `from(TemporalAccessor temporal)`
  Obtains a `HijrahDate` of the Islamic Umm Al-Qura calendar from a temporal object.
  `HijrahChronology`
  `getChronology()`
  Gets the chronology of this date, which is the Hijrah calendar system.
  `HijrahEra`
  `getEra()`
  Gets the era applicable at this date.
  `long`
  `getLong(TemporalField field)`
  Gets the value of the specified field as a `long`.
  `int`
  `hashCode()`
  A hash code for this date.
  `boolean`
  `isLeapYear()`
  Checks if the year is a leap year, according to the Hijrah calendar system rules.
  `int`
  `lengthOfMonth()`
  Returns the length of the month represented by this date.
  `int`
  `lengthOfYear()`
  Returns the length of the year represented by this date.
  `HijrahDate`
  `minus(long amountToSubtract, TemporalUnit unit)`
  Returns an object of the same type as this object with the specified period subtracted.
  `HijrahDate`
  `minus(TemporalAmount amount)`
  Returns an object of the same type as this object with an amount subtracted.
  `static HijrahDate`
  `now()`
  Obtains the current `HijrahDate` of the Islamic Umm Al-Qura calendar in the default time-zone.
  `static HijrahDate`
  `now(Clock clock)`
  Obtains the current `HijrahDate` of the Islamic Umm Al-Qura calendar from the specified clock.
  `static HijrahDate`
  `now(ZoneId zone)`
  Obtains the current `HijrahDate` of the Islamic Umm Al-Qura calendar in the specified time-zone.
  `static HijrahDate`
  `of(int prolepticYear, int month, int dayOfMonth)`
  Obtains a `HijrahDate` of the Islamic Umm Al-Qura calendar from the proleptic-year, month-of-year and day-of-month fields.
  `HijrahDate`
  `plus(long amountToAdd, TemporalUnit unit)`
  Returns an object of the same type as this object with the specified period added.
  `HijrahDate`
  `plus(TemporalAmount amount)`
  Returns an object of the same type as this object with an amount added.
  `String`
  `toString()`
  Outputs this date as a `String`.
  `ChronoPeriod`
  `until(ChronoLocalDate endDate)`
  Calculates the period between this date and another date as a `ChronoPeriod`.
  `long`
  `until(Temporal endExclusive, TemporalUnit unit)`
  Calculates the amount of time until another date in terms of the specified unit.
  `HijrahDate`
  `with(TemporalAdjuster adjuster)`
  Returns an adjusted object of the same type as this object with the adjustment made.
  `HijrahDate`
  `with(TemporalField field, long newValue)`
  Returns an object of the same type as this object with the specified field altered.
  `HijrahDate`
  `withVariant(HijrahChronology chronology)`
  Returns a `HijrahDate` with the Chronology requested.

  ### Methods declared in class Object

  `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

  ### Methods declared in interface ChronoLocalDate

  `adjustInto, compareTo, format, isAfter, isBefore, isEqual, isSupported, isSupported, query, toEpochDay, toString, until`

  ### Methods declared in interface TemporalAccessor

  `get, range`

- ## Method Details

  - ### now

    public static HijrahDate now()
    Obtains the current `HijrahDate` of the Islamic Umm Al-Qura calendar 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.

    Returns:
      the current date using the system clock and default time-zone, not null

  - ### now

    public static HijrahDate now(ZoneId zone)
    Obtains the current `HijrahDate` of the Islamic Umm Al-Qura calendar in the specified time-zone.

    This will query the `system clock` to obtain the current date. Specifying the time-zone avoids dependence on the default time-zone.

    Using this method will prevent the ability to use an alternate clock for testing because the clock is hard-coded.

    Parameters:
      `zone` - the zone ID to use, not null
    Returns:
      the current date using the system clock, not null

  - ### now

    public static HijrahDate now(Clock clock)
    Obtains the current `HijrahDate` of the Islamic Umm Al-Qura calendar from the specified clock.

    This will query the specified clock to obtain the current date - today. Using this method allows the use of an alternate clock for testing. The alternate clock may be introduced using dependency injection.

    Parameters:
      `clock` - the clock to use, not null
    Returns:
      the current date, not null
    Throws:
      `DateTimeException` - if the current date cannot be obtained

  - ### of

    public static HijrahDate of(int prolepticYear, int month, int dayOfMonth)
    Obtains a `HijrahDate` of the Islamic Umm Al-Qura calendar from the proleptic-year, month-of-year and day-of-month fields.

    This returns a `HijrahDate` with the specified fields. The day must be valid for the year and month, otherwise an exception will be thrown.

    Parameters:
      `prolepticYear` - the Hijrah proleptic-year
      `month` - the Hijrah month-of-year, from 1 to 12
      `dayOfMonth` - the Hijrah day-of-month, from 1 to 30
    Returns:
      the date in Hijrah calendar system, not null
    Throws:
      `DateTimeException` - if the value of any field is out of range, or if the day-of-month is invalid for the month-year

  - ### from

    public static HijrahDate from(TemporalAccessor temporal)
    Obtains a `HijrahDate` of the Islamic Umm Al-Qura calendar from a temporal object.

    This obtains a date in the Hijrah 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 `HijrahDate`.

    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, `HijrahDate::from`.

    Parameters:
      `temporal` - the temporal object to convert, not null
    Returns:
      the date in Hijrah calendar system, not null
    Throws:
      `DateTimeException` - if unable to convert to a `HijrahDate`

  - ### getChronology

    public HijrahChronology getChronology()
    Gets the chronology of this date, which is the Hijrah calendar system.

    The `Chronology` represents the calendar system in use. The era and other fields in `ChronoField` are defined by the chronology.

    Specified by:
      `getChronology` in interface `ChronoLocalDate`
    Returns:
      the Hijrah chronology, not null

  - ### getEra

    public HijrahEra getEra()
    Gets the era applicable at this date.

    The Hijrah calendar system has one era, 'AH', defined by `HijrahEra`.

    Specified by:
      `getEra` in interface `ChronoLocalDate`
    Returns:
      the era applicable at this date, not null

  - ### lengthOfMonth

    public int lengthOfMonth()
    Returns the length of the month represented by this date.

    This returns the length of the month in days. Month lengths in the Hijrah calendar system vary between 29 and 30 days.

    Specified by:
      `lengthOfMonth` in interface `ChronoLocalDate`
    Returns:
      the length of the month in days

  - ### lengthOfYear

    public int lengthOfYear()
    Returns the length of the year represented by this date.

    This returns the length of the year in days. A Hijrah calendar system year is typically shorter than that of the ISO calendar system.

    Specified by:
      `lengthOfYear` in interface `ChronoLocalDate`
    Returns:
      the length of the year in days

  - ### getLong

    public 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.

    Specified by:
      `getLong` in interface `TemporalAccessor`
    Parameters:
      `field` - the field to get, not null
    Returns:
      the value for the field

  - ### with

    public HijrahDate with(TemporalField field, long newValue)
    Description copied from interface: `Temporal`
    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.

    Specified by:
      `with` in interface `ChronoLocalDate`
    Specified by:
      `with` in interface `Temporal`
    Parameters:
      `field` - the field to set in the result, not null
      `newValue` - the new value of the field in the result
    Returns:
      an object of the same type with the specified field set, not null

  - ### with

    public HijrahDate 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

    Specified by:
      `with` in interface `ChronoLocalDate`
    Specified by:
      `with` in interface `Temporal`
    Parameters:
      `adjuster` - the adjuster to use, not null
    Returns:
      an object of the same type with the specified adjustment made, not null
    Throws:
      `DateTimeException` - if unable to make the adjustment. For example, if the adjuster requires an ISO chronology
      `ArithmeticException` - if numeric overflow occurs

  - ### withVariant

    public HijrahDate withVariant(HijrahChronology chronology)
    Returns a `HijrahDate` with the Chronology requested.

    The year, month, and day are checked against the new requested HijrahChronology. If the chronology has a shorter month length for the month, the day is reduced to be the last day of the month.

    Parameters:
      `chronology` - the new HijrahChonology, non-null
    Returns:
      a HijrahDate with the requested HijrahChronology, non-null

  - ### plus

    public HijrahDate 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.

    Specified by:
      `plus` in interface `ChronoLocalDate`
    Specified by:
      `plus` in interface `Temporal`
    Parameters:
      `amount` - the amount to add, not null
    Returns:
      an object of the same type with the specified adjustment made, not null
    Throws:
      `DateTimeException` - if the addition cannot be made
      `ArithmeticException` - if numeric overflow occurs

  - ### minus

    public HijrahDate 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.

    Specified by:
      `minus` in interface `ChronoLocalDate`
    Specified by:
      `minus` in interface `Temporal`
    Parameters:
      `amount` - the amount to subtract, not null
    Returns:
      an object of the same type with the specified adjustment made, not null
    Throws:
      `DateTimeException` - if the subtraction cannot be made
      `ArithmeticException` - if numeric overflow occurs

  - ### isLeapYear

    public boolean isLeapYear()
    Checks if the year is a leap year, according to the Hijrah calendar system rules.
    Specified by:
      `isLeapYear` in interface `ChronoLocalDate`
    Returns:
      true if this date is in a leap year

  - ### plus

    public HijrahDate plus(long amountToAdd, TemporalUnit unit)
    Description copied from interface: `Temporal`
    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.

    Specified by:
      `plus` in interface `ChronoLocalDate`
    Specified by:
      `plus` in interface `Temporal`
    Parameters:
      `amountToAdd` - the amount of the specified unit to add, may be negative
      `unit` - the unit of the amount to add, not null
    Returns:
      an object of the same type with the specified period added, not null

  - ### minus

    public HijrahDate minus(long amountToSubtract, TemporalUnit unit)
    Description copied from interface: `Temporal`
    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.

    Specified by:
      `minus` in interface `ChronoLocalDate`
    Specified by:
      `minus` in interface `Temporal`
    Parameters:
      `amountToSubtract` - the amount of the specified unit to subtract, may be negative
      `unit` - the unit of the amount to subtract, not null
    Returns:
      an object of the same type with the specified period subtracted, not null

  - ### atTime

    public final ChronoLocalDateTime<HijrahDate> 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.

    Specified by:
      `atTime` in interface `ChronoLocalDate`
    Parameters:
      `localTime` - the local time to use, not null
    Returns:
      the local date-time formed from this date and the specified time, not null

  - ### until

    public 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.

    Specified by:
      `until` in interface `ChronoLocalDate`
    Parameters:
      `endDate` - the end date, exclusive, which may be in any chronology, not null
    Returns:
      the period between this date and the end date, not null

  - ### equals

    public boolean equals(Object obj)
    Compares this date to another date, including the chronology.

    Compares this `HijrahDate` with another ensuring that the date is the same.

    Only objects of type `HijrahDate` 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.

    Specified by:
      `equals` in interface `ChronoLocalDate`
    Parameters:
      `obj` - the object to check, null returns false
    Returns:
      true if this is equal to the other date and the Chronologies are equal
    See Also:
      - `Object.hashCode()`
      - `HashMap`

  - ### hashCode

    public int hashCode()
    A hash code for this date.
    Specified by:
      `hashCode` in interface `ChronoLocalDate`
    Returns:
      a suitable hash code based only on the Chronology and the date
    See Also:
      - `Object.equals(java.lang.Object)`
      - `System.identityHashCode(Object)`

  - ### until

    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.

    Specified by:
      `until` in interface `ChronoLocalDate`
    Specified by:
      `until` in interface `Temporal`
    Parameters:
      `endExclusive` - the end date, exclusive, which is converted to a `ChronoLocalDate` in the same chronology, not null
      `unit` - the unit to measure the amount in, not null
    Returns:
      the amount of time between this date and the end date

  - ### toString

    public String toString()
    Description copied from interface: `ChronoLocalDate`
    Outputs this date as a `String`.

    The output will include the full local date.

    Specified by:
      `toString` in interface `ChronoLocalDate`
    Overrides:
      `toString` in class `Object`
    Returns:
      the formatted date, not null