Package org.threeten.bp.temporal

Interface TemporalUnit

  • All Known Implementing Classes:
    ChronoUnit
    public interface TemporalUnit
    A unit of date-time, such as Days or Hours.

    Measurement of time is built on units, such as years, months, days, hours, minutes and seconds. Implementations of this interface represent those units.

    An instance of this interface represents the unit itself, rather than an amount of the unit. See Period for a class that represents an amount in terms of the common units.

    The most commonly used units are defined in ChronoUnit. Further units are supplied in IsoFields. Units can also be written by application code by implementing this interface.

    The unit works using double dispatch. Client code calls methods on a date-time like LocalDateTime which check if the unit is a ChronoUnit. If it is, then the date-time must handle it. Otherwise, the method call is re-dispatched to the matching method in this interface.

    Specification for implementors

    This interface must be implemented with care to ensure other classes operate correctly. All implementations that can be instantiated must be final, immutable and thread-safe. It is recommended to use an enum where possible.

    • Method Summary

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      <R extends Temporal>
      R      		 addTo​(R dateTime, long periodToAdd)
      Returns a copy of the specified temporal object with the specified period added.
      long between​(Temporal temporal1, Temporal temporal2)
      Calculates the period in terms of this unit between two temporal objects of the same type.
      Duration getDuration()
      Gets the duration of this unit, which may be an estimate.
      boolean isDateBased()
      Checks if this unit is date-based.
      boolean isDurationEstimated()
      Checks if the duration of the unit is an estimate.
      boolean isSupportedBy​(Temporal temporal)
      Checks if this unit is supported by the specified temporal object.
      boolean isTimeBased()
      Checks if this unit is time-based.
      String toString()
      Outputs this unit as a String using the name.

    • Method Detail

      • getDuration

        Duration getDuration()
        Gets the duration of this unit, which may be an estimate.

        All units return a duration measured in standard nanoseconds from this method. The duration will be positive and non-zero. For example, an hour has a duration of 60 * 60 * 1,000,000,000ns.

        Some units may return an accurate duration while others return an estimate. For example, days have an estimated duration due to the possibility of daylight saving time changes. To determine if the duration is an estimate, use isDurationEstimated().

        Returns:
        the duration of this unit, which may be an estimate, not null

      • isDurationEstimated

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

        All units have a duration, however the duration is not always accurate. For example, days have an estimated duration due to the possibility of daylight saving time changes. This method returns true if the duration is an estimate and false if it is accurate. Note that accurate/estimated ignores leap seconds.

        Returns:
        true if the duration is estimated, false if accurate

      • isDateBased

        boolean isDateBased()
        Checks if this unit is date-based.
        Returns:
        true if date-based

      • isTimeBased

        boolean isTimeBased()
        Checks if this unit is time-based.
        Returns:
        true if time-based

      • isSupportedBy

        boolean isSupportedBy​(Temporal temporal)
        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.

        Parameters:
        temporal - the temporal object to check, not null
        Returns:
        true if the unit is supported

      • addTo

        <R extends Temporal> R addTo​(R dateTime,
                             long periodToAdd)
        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.doPlus(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 field is not supported a DateTimeException 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.

        Type Parameters:
        R - the type of the Temporal object
        Parameters:
        dateTime - the temporal object to adjust, not null
        periodToAdd - the period of this unit to add, positive or negative
        Returns:
        the adjusted temporal object, not null
        Throws:
        DateTimeException - if the period cannot be added

      • between

        long between​(Temporal temporal1,
             Temporal temporal2)
        Calculates the period in terms of this unit between two temporal objects of the same type.

        This calculates the period between two temporals in terms of this unit. The start and end points are supplied as temporal objects and must be of the same type. The result will be negative if the end is before the start. For example, the period 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 period in hours between the times 11:30 and 13:29 will only b 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 a DateTimeException must be thrown. Implementations must not alter the specified temporal objects.
        Parameters:
        temporal1 - the base temporal object, not null
        temporal2 - the other temporal object, not null
        Returns:
        the period between temporal1 and temporal2 in terms of this unit; positive if temporal2 is later than temporal1, negative if earlier
        Throws:
        DateTimeException - if the period cannot be calculated
        ArithmeticException - if numeric overflow occurs

      • toString

        String toString()
        Outputs this unit as a String using the name.
        Overrides:
        toString in class Object
        Returns:
        the name of this unit, not null