net.time4j.tz

Class ZonalTransition

java.lang.Object

net.time4j.tz.ZonalTransition

All Implemented Interfaces:

Serializable, Comparable<ZonalTransition>

public final class ZonalTransition
extends Object
implements Comparable<ZonalTransition>, Serializable

Represents the change of a shift of the local time relative to POSIX-time in any timezone.

This class contains informations about the global timestamp of the transition and the shifts/offsets before and after the transitions. A change of a zonal shift can either be caused by special historical events and political actions (change of standard time) or by establishing daylight saving-rules (change from winter time to summer time and reverse - DST). Therefore the total shift getTotalOffset() is always the sum of the parts getStandardOffset() and getDaylightSavingOffset().

Shifts are described on the local timeline in seconds. Following relationship holds between local time and POSIX-time:

getTotalOffset() = [Local Wall Time] - [POSIX Time]

A zonal transition induces a gap on the local timeline if the new shift is greater than the old shift. And an overlap occurs if the new shift is smaller than the old shift. A local time is not defined within gaps and ambivalent in overlapping regions.

Author:

Meno Hochschild

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ZonalTransition(long posixTime, int previousOffset, int totalOffset, int daylightSavingOffset) Creates a new transition between two shifts.

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(ZonalTransition other) Compares preferrably the timeline order based on the global timestamps of transitions, otherwise the total shift and finally the DST-shift.
boolean	equals(Object obj) Based on the whole state with global POSIX-timestamp and all internal shifts.
int	getDaylightSavingOffset() Returns the DST-shift (daylight savings) after this transition that is the shift induced by change to summer time.
long	getPosixTime() Returns the global timestamp of this transition from one shift to another as POSIX-timestamp.
int	getPreviousOffset() Returns the total shift before this transition.
int	getSize() Gets the difference between new and old total shift as measure for the size of this transition.
int	getStandardOffset() Returns the standard shift after this transition as difference between total shift and DST-shift (daylight savings).
int	getTotalOffset() Returns the total shift after this transition.
int	hashCode() Based on the POSIX-timestamp of the transition.
boolean	isDaylightSaving() Queries if there is any daylight savings after this transition.
boolean	isGap() Queries if this transition represents a gap on the local timeline where local timestamps are invalid.
boolean	isOverlap() Queries if this transition represents an overlap on the local timeline where local timestamps are ambivalent.
String	toString() Supports debugging.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ZonalTransition

public ZonalTransition(long posixTime,
               int previousOffset,
               int totalOffset,
               int daylightSavingOffset)

Creates a new transition between two shifts.

Parameters:

posixTime - POSIX time of transition

previousOffset - previous total shift in seconds

totalOffset - new total shift in seconds

daylightSavingOffset - DST-shift in seconds

Throws:

IllegalArgumentException - if the DST-shift is negative

See Also:

UnixTime.getPosixTime(), ZonalOffset.getIntegralAmount()

Method Detail

getPosixTime

public long getPosixTime()

Returns the global timestamp of this transition from one shift to another as POSIX-timestamp.

Returns:

transition time relative to [1970-01-01T00:00:00] in seconds (without leap seconds)

See Also:

TimeScale.POSIX

getPreviousOffset

public int getPreviousOffset()

Returns the total shift before this transition.

Returns:

previous total shift in seconds

See Also:

getTotalOffset(), ZonalOffset.getIntegralAmount()

getTotalOffset

public int getTotalOffset()

Returns the total shift after this transition.

Returns:

new total shift in seconds

See Also:

getPreviousOffset(), getStandardOffset(), getDaylightSavingOffset(), isDaylightSaving(), ZonalOffset.getIntegralAmount()

getStandardOffset

public int getStandardOffset()

Returns the standard shift after this transition as difference between total shift and DST-shift (daylight savings).

Negative standard shifts are related to timezones west for Greenwich, positive to timezones east for Greenwich. The addition of the standard shift to POSIX-time yields the standard local time corresponding to winter time.

Returns:

raw shift in seconds after transition

See Also:

getTotalOffset(), getDaylightSavingOffset(), isDaylightSaving()

getDaylightSavingOffset

public int getDaylightSavingOffset()

Returns the DST-shift (daylight savings) after this transition that is the shift induced by change to summer time.

If the method isDaylightSaving() yields the value false then this method will simply yield 0.

Returns:

daylight-saving-shift in seconds after transition

See Also:

getTotalOffset(), getStandardOffset(), isDaylightSaving()

isDaylightSaving

public boolean isDaylightSaving()

Queries if there is any daylight savings after this transition.

Returns:

boolean

See Also:

getDaylightSavingOffset()

getSize

public int getSize()

Gets the difference between new and old total shift as measure for the size of this transition.

Returns:

change of total shift in seconds

isGap

public boolean isGap()

Queries if this transition represents a gap on the local timeline where local timestamps are invalid.

Returns:

true if this transition represents a gap (by definition the new total shift is bigger than the previous one) else false

isOverlap

public boolean isOverlap()

Queries if this transition represents an overlap on the local timeline where local timestamps are ambivalent.

Returns:

true if this transition represents an overlap (by definition the new total shift is smaller than the previous one) else false

compareTo

public int compareTo(ZonalTransition other)

Compares preferrably the timeline order based on the global timestamps of transitions, otherwise the total shift and finally the DST-shift.

The natural order is consistent with equals().

Specified by:

compareTo in interface Comparable<ZonalTransition>

equals

public boolean equals(Object obj)

Based on the whole state with global POSIX-timestamp and all internal shifts.

Overrides:

equals in class Object

hashCode

public int hashCode()

Based on the POSIX-timestamp of the transition.

Overrides:

hashCode in class Object

toString

public String toString()

Supports debugging.

Overrides:

toString in class Object

Returns:

String