Module java.base
Package java.time.temporal

Enum Class ChronoUnit

java.lang.Object
java.lang.Enum<ChronoUnit>
java.time.temporal.ChronoUnit
All Implemented Interfaces:
Serializable, Comparable<ChronoUnit>, Constable, 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

  • Nested Class Summary

    Nested classes/interfaces declared in class java.lang.Enum

    Enum.EnumDesc<E extends Enum<E>>

  • Enum Constant Summary

    Enum Constants
    Enum Constant
    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.

  • Method Summary

    Modifier and Type
    Method
    Description
    <R extends Temporal>
    R
    addTo​(R temporal, long amount)
    Returns a copy of the specified temporal object with the specified period added.
    long
    between​(Temporal temporal1Inclusive, Temporal temporal2Exclusive)
    Calculates the amount of time between two temporal objects.
    Duration
    getDuration()
    Gets the estimated duration of this unit in the ISO calendar system.
    boolean
    isDateBased()
    Checks if this unit is a date unit.
    boolean
    isDurationEstimated()
    Checks if the duration of the unit is an estimate.
    boolean
    isTimeBased()
    Checks if this unit is a time unit.
    String
    toString()
    Returns the name of this enum constant, as contained in the declaration.
    static ChronoUnit
    valueOf​(String name)
    Returns the enum constant of this class with the specified name.
    static ChronoUnit[]
    values()
    Returns an array containing the constants of this enum class, in the order they are declared.

    Methods declared in class java.lang.Enum

    clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

    Methods declared in class java.lang.Object

    getClass, notify, notifyAll, wait, wait, wait

    Methods declared in interface java.time.temporal.TemporalUnit

    isSupportedBy

  • Enum Constant Details

    • 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 this unit is artificially defined as the largest duration supported by Duration.

  • Method Details

    • values

      public static ChronoUnit[] values()
      Returns an array containing the constants of this enum class, in the order they are declared.
      Returns:
      an array containing the constants of this enum class, in the order they are declared

    • valueOf

      public static ChronoUnit valueOf​(String name)
      Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (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 class 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

    • 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 class 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