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Java Standard Edition (SE)

ChronoUnit


compact1, compact2, compact3
java.time.temporal

Enum ChronoUnit

  • All Implemented Interfaces:
    Serializable, Comparable<ChronoUnit>, TemporalUnit


    public enum ChronoUnit
    extends Enum<ChronoUnit>
    implements TemporalUnit
    A standard set of date periods units.

    This set of units provide unit-based access to manipulate a date, time or date-time. The standard set of units can be extended by implementing TemporalUnit.

    These units are intended to be applicable in multiple calendar systems. For example, most non-ISO calendar systems define units of years, months and days, just with slightly different rules. The documentation of each unit explains how it operates.

    Implementation Requirements:
    This is a final, immutable and thread-safe enum.
    Since:
    1.8
    • Enum Constant Summary

      Enum Constants 
      Enum Constant and Description
      CENTURIES
      Unit that represents the concept of a century.
      DAYS
      Unit that represents the concept of a day.
      DECADES
      Unit that represents the concept of a decade.
      ERAS
      Unit that represents the concept of an era.
      FOREVER
      Artificial unit that represents the concept of forever.
      HALF_DAYS
      Unit that represents the concept of half a day, as used in AM/PM.
      HOURS
      Unit that represents the concept of an hour.
      MICROS
      Unit that represents the concept of a microsecond.
      MILLENNIA
      Unit that represents the concept of a millennium.
      MILLIS
      Unit that represents the concept of a millisecond.
      MINUTES
      Unit that represents the concept of a minute.
      MONTHS
      Unit that represents the concept of a month.
      NANOS
      Unit that represents the concept of a nanosecond, the smallest supported unit of time.
      SECONDS
      Unit that represents the concept of a second.
      WEEKS
      Unit that represents the concept of a week.
      YEARS
      Unit that represents the concept of a year.
    • Enum Constant Detail

      • NANOS

        public static final ChronoUnit NANOS
        Unit that represents the concept of a nanosecond, the smallest supported unit of time. For the ISO calendar system, it is equal to the 1,000,000,000th part of the second unit.
      • MICROS

        public static final ChronoUnit MICROS
        Unit that represents the concept of a microsecond. For the ISO calendar system, it is equal to the 1,000,000th part of the second unit.
      • MILLIS

        public static final ChronoUnit MILLIS
        Unit that represents the concept of a millisecond. For the ISO calendar system, it is equal to the 1000th part of the second unit.
      • SECONDS

        public static final ChronoUnit SECONDS
        Unit that represents the concept of a second. For the ISO calendar system, it is equal to the second in the SI system of units, except around a leap-second.
      • MINUTES

        public static final ChronoUnit MINUTES
        Unit that represents the concept of a minute. For the ISO calendar system, it is equal to 60 seconds.
      • HOURS

        public static final ChronoUnit HOURS
        Unit that represents the concept of an hour. For the ISO calendar system, it is equal to 60 minutes.
      • HALF_DAYS

        public static final ChronoUnit HALF_DAYS
        Unit that represents the concept of half a day, as used in AM/PM. For the ISO calendar system, it is equal to 12 hours.
      • DAYS

        public static final ChronoUnit DAYS
        Unit that represents the concept of a day. For the ISO calendar system, it is the standard day from midnight to midnight. The estimated duration of a day is 24 Hours.

        When used with other calendar systems it must correspond to the day defined by the rising and setting of the Sun on Earth. It is not required that days begin at midnight - when converting between calendar systems, the date should be equivalent at midday.

      • WEEKS

        public static final ChronoUnit WEEKS
        Unit that represents the concept of a week. For the ISO calendar system, it is equal to 7 days.

        When used with other calendar systems it must correspond to an integral number of days.

      • MONTHS

        public static final ChronoUnit MONTHS
        Unit that represents the concept of a month. For the ISO calendar system, the length of the month varies by month-of-year. The estimated duration of a month is one twelfth of 365.2425 Days.

        When used with other calendar systems it must correspond to an integral number of days.

      • YEARS

        public static final ChronoUnit YEARS
        Unit that represents the concept of a year. For the ISO calendar system, it is equal to 12 months. The estimated duration of a year is 365.2425 Days.

        When used with other calendar systems it must correspond to an integral number of days or months roughly equal to a year defined by the passage of the Earth around the Sun.

      • DECADES

        public static final ChronoUnit DECADES
        Unit that represents the concept of a decade. For the ISO calendar system, it is equal to 10 years.

        When used with other calendar systems it must correspond to an integral number of days and is normally an integral number of years.

      • CENTURIES

        public static final ChronoUnit CENTURIES
        Unit that represents the concept of a century. For the ISO calendar system, it is equal to 100 years.

        When used with other calendar systems it must correspond to an integral number of days and is normally an integral number of years.

      • MILLENNIA

        public static final ChronoUnit MILLENNIA
        Unit that represents the concept of a millennium. For the ISO calendar system, it is equal to 1000 years.

        When used with other calendar systems it must correspond to an integral number of days and is normally an integral number of years.

      • ERAS

        public static final ChronoUnit ERAS
        Unit that represents the concept of an era. The ISO calendar system doesn't have eras thus it is impossible to add an era to a date or date-time. The estimated duration of the era is artificially defined as 1,000,000,000 Years.

        When used with other calendar systems there are no restrictions on the unit.

      • FOREVER

        public static final ChronoUnit FOREVER
        Artificial unit that represents the concept of forever. This is primarily used with TemporalField to represent unbounded fields such as the year or era. The estimated duration of the era is artificially defined as the largest duration supported by Duration.
    • Method Detail

      • values

        public static ChronoUnit[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:
        for (ChronoUnit c : ChronoUnit.values())
            System.out.println(c);
        
        Returns:
        an array containing the constants of this enum type, in the order they are declared
      • valueOf

        public static ChronoUnit valueOf(String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)
        Parameters:
        name - the name of the enum constant to be returned.
        Returns:
        the enum constant with the specified name
        Throws:
        IllegalArgumentException - if this enum type has no constant with the specified name
        NullPointerException - if the argument is null
      • getDuration

        public Duration getDuration()
        Gets the estimated duration of this unit in the ISO calendar system.

        All of the units in this class have an estimated duration. Days vary due to daylight saving time, while months have different lengths.

        Specified by:
        getDuration in interface TemporalUnit
        Returns:
        the estimated duration of this unit, not null
      • isDurationEstimated

        public boolean isDurationEstimated()
        Checks if the duration of the unit is an estimate.

        All time units in this class are considered to be accurate, while all date units in this class are considered to be estimated.

        This definition ignores leap seconds, but considers that Days vary due to daylight saving time and months have different lengths.

        Specified by:
        isDurationEstimated in interface TemporalUnit
        Returns:
        true if the duration is estimated, false if accurate
      • isDateBased

        public boolean isDateBased()
        Checks if this unit is a date unit.

        All units from days to eras inclusive are date-based. Time-based units and FOREVER return false.

        Specified by:
        isDateBased in interface TemporalUnit
        Returns:
        true if a date unit, false if a time unit
      • isTimeBased

        public boolean isTimeBased()
        Checks if this unit is a time unit.

        All units from nanos to half-days inclusive are time-based. Date-based units and FOREVER return false.

        Specified by:
        isTimeBased in interface TemporalUnit
        Returns:
        true if a time unit, false if a date unit
      • isSupportedBy

        public boolean isSupportedBy(Temporal temporal)
        Description copied from interface: TemporalUnit
        Checks if this unit is supported by the specified temporal object.

        This checks that the implementing date-time can add/subtract this unit. This can be used to avoid throwing an exception.

        This default implementation derives the value using Temporal.plus(long, TemporalUnit).

        Specified by:
        isSupportedBy in interface TemporalUnit
        Parameters:
        temporal - the temporal object to check, not null
        Returns:
        true if the unit is supported
      • addTo

        public <R extends Temporal> R addTo(R temporal,
                                            long amount)
        Description copied from interface: TemporalUnit
        Returns a copy of the specified temporal object with the specified period added.

        The period added is a multiple of this unit. For example, this method could be used to add "3 days" to a date by calling this method on the instance representing "days", passing the date and the period "3". The period to be added may be negative, which is equivalent to subtraction.

        There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use Temporal.plus(long, TemporalUnit):

           // these two lines are equivalent, but the second approach is recommended
           temporal = thisUnit.addTo(temporal);
           temporal = temporal.plus(thisUnit);
         
        It is recommended to use the second approach, plus(TemporalUnit), as it is a lot clearer to read in code.

        Implementations should perform any queries or calculations using the units available in ChronoUnit or the fields available in ChronoField. If the unit is not supported an UnsupportedTemporalTypeException must be thrown.

        Implementations must not alter the specified temporal object. Instead, an adjusted copy of the original must be returned. This provides equivalent, safe behavior for immutable and mutable implementations.

        Specified by:
        addTo in interface TemporalUnit
        Type Parameters:
        R - the type of the Temporal object
        Parameters:
        temporal - the temporal object to adjust, not null
        amount - the amount of this unit to add, positive or negative
        Returns:
        the adjusted temporal object, not null
      • between

        public long between(Temporal temporal1Inclusive,
                            Temporal temporal2Exclusive)
        Description copied from interface: TemporalUnit
        Calculates the amount of time between two temporal objects.

        This calculates the amount in terms of this unit. The start and end points are supplied as temporal objects and must be of compatible types. The implementation will convert the second type to be an instance of the first type before the calculating the amount. The result will be negative if the end is before the start. For example, the amount in hours between two temporal objects can be calculated using HOURS.between(startTime, endTime).

        The calculation returns a whole number, representing the number of complete units between the two temporals. For example, the amount in hours between the times 11:30 and 13:29 will only be one hour as it is one minute short of two hours.

        There are two equivalent ways of using this method. The first is to invoke this method directly. The second is to use Temporal.until(Temporal, TemporalUnit):

           // these two lines are equivalent
           between = thisUnit.between(start, end);
           between = start.until(end, thisUnit);
         
        The choice should be made based on which makes the code more readable.

        For example, this method allows the number of days between two dates to be calculated:

          long daysBetween = DAYS.between(start, end);
          // or alternatively
          long daysBetween = start.until(end, DAYS);
         

        Implementations should perform any queries or calculations using the units available in ChronoUnit or the fields available in ChronoField. If the unit is not supported an UnsupportedTemporalTypeException must be thrown. Implementations must not alter the specified temporal objects.

        Specified by:
        between in interface TemporalUnit
        Parameters:
        temporal1Inclusive - the base temporal object, not null
        temporal2Exclusive - the other temporal object, exclusive, not null
        Returns:
        the amount of time between temporal1Inclusive and temporal2Exclusive in terms of this unit; positive if temporal2Exclusive is later than temporal1Inclusive, negative if earlier
      • toString

        public String toString()
        Description copied from class: Enum
        Returns the name of this enum constant, as contained in the declaration. This method may be overridden, though it typically isn't necessary or desirable. An enum type should override this method when a more "programmer-friendly" string form exists.
        Specified by:
        toString in interface TemporalUnit
        Overrides:
        toString in class Enum<ChronoUnit>
        Returns:
        the name of this enum constant


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