net.time4j.tz

Interface TransitionHistory

public interface TransitionHistory

Keeps all offset transitions and rules of a timezone.

Author:

Meno Hochschild

Method Summary

Methods

Modifier and Type	Method and Description
ZonalTransition	getConflictTransition(GregorianDate localDate, WallTime localTime) Returns the conflict transition where given local timestamp falls either in a gap or in an overlap on the local timeline.
ZonalOffset	getInitialOffset() Return the initial offset no matter if there are any transitions defined or not.
ZonalTransition	getStartTransition(UnixTime ut) Queries the last transition which defines the offset for given global timestamp.
List<ZonalTransition>	getStdTransitions() Return the offset transitions from UNIX epoch [1970-01-01T00:00Z] until at maximum the first transition after the current timestamp.
List<ZonalTransition>	getStdTransitionsAfter(UnixTime ut) Returns the next transitions in ascending order if available.
List<ZonalTransition>	getStdTransitionsBefore(UnixTime ut) Returns the previous transitions in descending order if available.
List<ZonalTransition>	getTransitions(UnixTime startInclusive, UnixTime endExclusive) Returns the defined transitions in given POSIX-interval.
List<ZonalOffset>	getValidOffsets(GregorianDate localDate, WallTime localTime) Determines the suitable offsets at given local timestamp..

Method Detail

getInitialOffset

ZonalOffset getInitialOffset()

Return the initial offset no matter if there are any transitions defined or not.

If any transition is defined then the initial offset is identical to the shift getPreviousOffset() of the first defined transition in history.

Returns:

fixed initial shift

getStartTransition

ZonalTransition getStartTransition(UnixTime ut)

Queries the last transition which defines the offset for given global timestamp.

Parameters:

ut - unix reference time

Returns:

ZonalTransition or null if given reference time is before first defined transition

getConflictTransition

ZonalTransition getConflictTransition(GregorianDate localDate,
                                    WallTime localTime)

Returns the conflict transition where given local timestamp falls either in a gap or in an overlap on the local timeline.

Parameters:

localDate - local date in timezone

localTime - local wall time in timezone

Returns:

conflict transition on the local time axis for gaps or overlaps else null

See Also:

getValidOffsets(GregorianDate,WallTime)

getValidOffsets

List<ZonalOffset> getValidOffsets(GregorianDate localDate,
                                WallTime localTime)

Determines the suitable offsets at given local timestamp..

The offset list is empty if the local timestamp falls in a gap on the local timeline. The list has exactly two offsets if the local timestamp belongs to two different timepoints on the POSIX timescale due to an overlap. Otherwise the offset list will contain exactly one suitable offset.

Parameters:

localDate - local date in timezone

localTime - local wall time in timezone

Returns:

unmodifiable list of shifts which fits the given local time

See Also:

getConflictTransition(GregorianDate,WallTime)

getStdTransitions

List<ZonalTransition> getStdTransitions()

Return the offset transitions from UNIX epoch [1970-01-01T00:00Z] until at maximum the first transition after the current timestamp.

Indeed, a potentially bigger interval is obtainable by getTransitions(UnixTime,UnixTime), but earlier or later timepoints are usually not reliable. For example the wide-spread IANA/Olson-repository is only designed for times since UNIX epoch and offers some selected older data to the best of our knowledge. Users must be aware that even older data can be changed as side effect of data corrections. Generally the timezone concept was invented in 19th century. And future transitions are even less reliable due to political arbitrariness.

Returns:

unmodifiable list of standard transitions (after 1970-01-01) maybe empty

getStdTransitionsBefore

List<ZonalTransition> getStdTransitionsBefore(UnixTime ut)

Returns the previous transitions in descending order if available.

In general, this method will only yield transitions in the interval from [1970-01-01T00:00Z] until at maximum the first transition before the current timestamp (in descending order on the timeline!).

Parameters:

ut - unix reference time

Returns:

previous transitions before reference time (only standard transitions after 1970-01-01)

See Also:

getStdTransitions()

getStdTransitionsAfter

List<ZonalTransition> getStdTransitionsAfter(UnixTime ut)

Returns the next transitions in ascending order if available.

In general, this method will only yield transitions in the interval from [1970-01-01T00:00Z] until at maximum the first transition before the current timestamp.

Parameters:

ut - unix reference time

Returns:

next transitions after reference time (only standard transitions 1970-01-01)

See Also:

getStdTransitions()

getTransitions

List<ZonalTransition> getTransitions(UnixTime startInclusive,
                                   UnixTime endExclusive)

Returns the defined transitions in given POSIX-interval.

Parameters:

startInclusive - start time on POSIX time scale

endExclusive - end time on POSIX time scale

Returns:

unmodifiable list of transitions maybe empty

See Also:

getStdTransitions()