Package org.threeten.extra.scale

Class UtcRules

java.lang.Object
org.threeten.extra.scale.UtcRules
public abstract class UtcRules extends Object
Rules defining the UTC time-scale, notably when leap seconds occur.

This class defines the UTC time-scale including when leap seconds occur. Subclasses obtain the data from a suitable source, such as a file.

The static methods on this class provide access to the system leap second rules. These are used by default in UtcInstant and TaiInstant. Using other rules requires manual use of this class.

The system rules can be updated using a LeapSeconds.txt} file. You can create your own version of this file and place it in on the classpath and it will be used. Due to Java 9 module restrictions, the file is located under META-INF to avoid module encapsulation problems - META-INF/org/threeten/extra/scale/LeapSeconds.txt.

Implementation Requirements:

This is an abstract class and must be implemented with care to ensure other classes in the framework operate correctly. All implementations must be final, immutable and thread-safe. Subclasses should be Serializable wherever possible.

  • Constructor Details

    • UtcRules

      protected UtcRules()
      Creates an instance of the rules.

  • Method Details

    • system

      public static UtcRules system()
      Gets the system default leap second rules.

      The system default rules are serializable, immutable and thread-safe. They will remain up to date as new leap seconds are added.

      Returns:
      the system rules, not null

    • registerLeapSecond

      public static void registerLeapSecond(long mjDay, int leapAdjustment)
      Adds a new leap second to the system default leap second rules.

      This method registers a new leap second with the system leap second rules. Once registered, there is no way to deregister the leap second.

      Calling this method is thread-safe. Its effects are immediately visible in all threads. Where possible, only call this method from a single thread to avoid the possibility of a ConcurrentModificationException.

      If the leap second being added matches a previous definition, then the method returns normally. If the date is before the last registered date and does not match a previous definition, then an exception is thrown.

      Parameters:
      mjDay - the Modified Julian Day that the leap second occurs at the end of
      leapAdjustment - the leap seconds to add/remove at the end of the day, either -1 or 1
      Throws:
      IllegalArgumentException - if the leap adjustment is invalid
      IllegalArgumentException - if the day is before or equal the last known leap second day and the definition does not match a previously registered leap
      ConcurrentModificationException - if another thread updates the rules at the same time

    • getName

      public abstract String getName()
      The name of these rules.
      Returns:
      the name, not null

    • getLeapSecondAdjustment

      public abstract int getLeapSecondAdjustment(long mjDay)
      Gets the leap second adjustment on the specified date.

      The UTC standard restricts the adjustment on any day to -1 or 1.

      Any leap seconds are added to, or removed from, the end of the specified date.

      If the UTC specification is altered to allow multiple leap seconds at once, then the result of this method would return a number with an absolute value greater than one.

      Parameters:
      mjDay - the date as a Modified Julian Day (number of days from the epoch of 1858-11-17)
      Returns:
      the number of seconds added, or removed, from the date, either -1 or 1

    • getTaiOffset

      public abstract int getTaiOffset(long mjDay)
      Gets the offset to TAI on the specified date.

      The TAI offset starts at 10 in 1972 and varies from then on based on the dates of leap seconds. The offset will apply for the whole of the date.

      Parameters:
      mjDay - the date as a Modified Julian Day (number of days from the epoch of 1858-11-17)
      Returns:
      the TAI offset in seconds

    • getLeapSecondDates

      public abstract long[] getLeapSecondDates()
      Gets all known leap second dates.

      The dates are returned as Modified Julian Day values. The leap second is added to, or removed from, the end of the specified dates. The dates will be sorted from earliest to latest.

      Returns:
      an array of leap second dates expressed as Modified Julian Day values, not null

    • validateModifiedJulianDay

      public void validateModifiedJulianDay(long mjDay, long nanoOfDay)
      Validates combination of Modified Julian Day and nanosecond-of-day.

      Modified Julian Day is a simple incrementing count of days where day 0 is 1858-11-17. Nanosecond-of-day is a simple count of nanoseconds from the start of the day including any additional leap-second. This method validates the nanosecond-of-day value against the Modified Julian Day.

      The nanosecond-of-day value has a valid range from 0 to 86,400,000,000,000 - 1 on most days, and a larger or smaller range on leap-second days.

      Parameters:
      mjDay - the date as a Modified Julian Day (number of days from the epoch of 1858-11-17)
      nanoOfDay - the nanoseconds within the day, including leap seconds
      Throws:
      DateTimeException - if nanoOfDay is out of range

    • convertToTai

      public TaiInstant convertToTai(UtcInstant utcInstant)
      Converts a UtcInstant to a TaiInstant.

      This method converts from the UTC to the TAI time-scale using the leap-second rules of the implementation.

      Parameters:
      utcInstant - the UTC instant to convert, not null
      Returns:
      the converted TAI instant, not null
      Throws:
      DateTimeException - if the valid range is exceeded
      ArithmeticException - if numeric overflow occurs

    • convertToUtc

      public abstract UtcInstant convertToUtc(TaiInstant taiInstant)
      Converts a TaiInstant to a UtcInstant.

      This method converts from the TAI to the UTC time-scale using the leap-second rules of the implementation.

      Parameters:
      taiInstant - the TAI instant to convert, not null
      Returns:
      the converted UTC instant, not null
      Throws:
      DateTimeException - if the valid range is exceeded
      ArithmeticException - if numeric overflow occurs

    • convertToInstant

      public Instant convertToInstant(UtcInstant utcInstant)
      Converts a UtcInstant to an Instant.

      This method converts from the UTC time-scale to one with 86400 subdivisions per day using the leap-second rules of the implementation.

      The standard implementation uses the UTC-SLS algorithm. Overriding this algorithm is possible, however doing so will conflict other parts of the specification.

      The algorithm calculates the UTC-SLS nanos-of-day US from the UTC nanos-of day U.
      Let L = getLeapAdjustment(mjd).
      Let B = 86400 + L - 1000.
      Let US = U - L * (U - B) / 1000.
      Where the algorithm is applied while U >= B.

      Parameters:
      utcInstant - the UTC instant to convert, not null
      Returns:
      the converted instant, not null
      Throws:
      DateTimeException - if the valid range is exceeded
      ArithmeticException - if numeric overflow occurs

    • convertToUtc

      public UtcInstant convertToUtc(Instant instant)
      Converts an Instant to a UtcInstant.

      This method converts from an instant with 86400 subdivisions per day to the UTC time-scale using the leap-second rules of the implementation.

      The standard implementation uses the UTC-SLS algorithm. Overriding this algorithm is possible, however doing so will conflict other parts of the specification.

      The algorithm calculates the UTC nanos-of-day U from the UTC-SLS nanos-of day US.
      Let L = getLeapAdjustment(mjd).
      Let B = 86400 + L - 1000.
      Let U = B + ((US - B) * 1000) / (1000 - L).
      Where the algorithm is applied while US >= B.
      (This algorithm has been tuned for integer arithmetic from the UTC-SLS specification.)

      Parameters:
      instant - the instant to convert, not null
      Returns:
      the converted UTC instant, not null
      Throws:
      DateTimeException - if the valid range is exceeded
      ArithmeticException - if numeric overflow occurs

    • convertToInstant

      public Instant convertToInstant(TaiInstant taiInstant)
      Converts a TaiInstant to an Instant.

      This method converts from the TAI time-scale to one with 86400 subdivisions per day using the leap-second rules of the implementation.

      The standard implementation uses UTC-SLS. It uses convertToUtc(TaiInstant) and convertToInstant(UtcInstant).

      Parameters:
      taiInstant - the TAI instant to convert, not null
      Returns:
      the converted instant, not null
      Throws:
      DateTimeException - if the valid range is exceeded
      ArithmeticException - if numeric overflow occurs

    • convertToTai

      public TaiInstant convertToTai(Instant instant)
      Converts an Instant to a TaiInstant.

      This method converts from an instant with 86400 subdivisions per day to the TAI time-scale using the leap-second rules of the implementation.

      The standard implementation uses the UTC-SLS algorithm. It uses convertToUtc(TaiInstant) and convertToInstant(UtcInstant).

      Parameters:
      instant - the instant to convert, not null
      Returns:
      the converted instant, not null
      Throws:
      DateTimeException - if the valid range is exceeded
      ArithmeticException - if numeric overflow occurs

    • toString

      public String toString()
      A string representation of these rules.
      Overrides:
      toString in class Object
      Returns:
      the string representation, not null