Package com.ibm.icu.impl

Class OlsonTimeZone

  • All Implemented Interfaces:
    Freezable<TimeZone>, Serializable, Cloneable
    public class OlsonTimeZone
extends BasicTimeZone
    A time zone based on the Olson tz database. Olson time zones change behavior over time. The raw offset, rules, presence or absence of daylight savings time, and even the daylight savings amount can all vary. This class uses a resource bundle named "zoneinfo". Zoneinfo is a table containing different kinds of resources. In several places, zones are referred to using integers. A zone's integer is a number from 0..n-1, where n is the number of zones, with the zones sorted in lexicographic order. 1. Zones. These have keys corresponding to the Olson IDs, e.g., "Asia/Shanghai". Each resource describes the behavior of the given zone. Zones come in two different formats. a. Zone (table). A zone is a table resource contains several type of resources below: - typeOffsets:intvector (Required) Sets of UTC raw/dst offset pairs in seconds. Entries at 2n represents raw offset and 2n+1 represents dst offset paired with the raw offset at 2n. The very first pair represents the initial zone offset (before the first transition) always. - trans:intvector (Optional) List of transition times represented by 32bit seconds from the epoch (1970-01-01T00:00Z) in ascending order. - transPre32/transPost32:intvector (Optional) List of transition times before/after 32bit minimum seconds. Each time is represented by a pair of 32bit integer. - typeMap:bin (Optional) Array of bytes representing the mapping between each transition time (transPre32/trans/transPost32) and its corresponding offset data (typeOffsets). - finalRule:string (Optional) If a recurrent transition rule is applicable to a zone forever after the final transition time, finalRule represents the rule in Rules data. - finalRaw:int (Optional) When finalRule is available, finalRaw is required and specifies the raw (base) offset of the rule. - finalYear:int (Optional) When finalRule is available, finalYear is required and specifies the start year of the rule. - links:intvector (Optional) When this zone data is shared with other zones, links specifies all zones including the zone itself. Each zone is referenced by integer index. b. Link (int, length 1). A link zone is an int resource. The integer is the zone number of the target zone. The key of this resource is an alternate name for the target zone. This data is corresponding to Link data in the tz database. 2. Rules. These have keys corresponding to the Olson rule IDs, with an underscore prepended, e.g., "_EU". Each resource describes the behavior of the given rule using an intvector, containing the onset list, the cessation list, and the DST savings. The onset and cessation lists consist of the month, dowim, dow, time, and time mode. The end result is that the 11 integers describing the rule can be passed directly into the SimpleTimeZone 13-argument constructor (the other two arguments will be the raw offset, taken from the complex zone element 5, and the ID string, which is not used), with the times and the DST savings multiplied by 1000 to scale from seconds to milliseconds. 3. Regions. An array specifies mapping between zones and regions. Each item is either a 2-letter ISO country code or "001" (UN M.49 - World). This data is generated from "zone.tab" in the tz database.
    See Also:
    Serialized Form

    • Constructor Detail

      • OlsonTimeZone

        public OlsonTimeZone​(UResourceBundle top,
                     UResourceBundle res,
                     String id)
        Construct from a resource bundle
        Parameters:
        top - the top-level zoneinfo resource bundle. This is used to lookup the rule that `res' may refer to, if there is one.
        res - the resource bundle of the zone to be constructed
        id - time zone ID

      • OlsonTimeZone

        public OlsonTimeZone​(String id)

    • Method Detail

      • getOffset

        public int getOffset​(int era,
                     int year,
                     int month,
                     int day,
                     int dayOfWeek,
                     int milliseconds)
        Description copied from class: TimeZone
        Gets the time zone offset, for current date, modified in case of daylight savings. This is the offset to add *to* UTC to get local time.
        Specified by:
        getOffset in class TimeZone
        Parameters:
        era - the era of the given date.
        year - the year in the given date.
        month - the month in the given date. Month is 0-based. e.g., 0 for January.
        day - the day-in-month of the given date.
        dayOfWeek - the day-of-week of the given date.
        milliseconds - the millis in day in standard local time.
        Returns:
        the offset to add *to* GMT to get local time.

      • getOffset

        public int getOffset​(int era,
                     int year,
                     int month,
                     int dom,
                     int dow,
                     int millis,
                     int monthLength)
        TimeZone API.

      • setRawOffset

        public void setRawOffset​(int offsetMillis)
        Description copied from class: TimeZone
        Sets the base time zone offset to GMT. This is the offset to add *to* UTC to get local time.
        Specified by:
        setRawOffset in class TimeZone
        Parameters:
        offsetMillis - the given base time zone offset to GMT.

      • clone

        public Object clone()
        Description copied from class: TimeZone
        Overrides clone.
        Overrides:
        clone in class TimeZone
        Returns:
        a copy of this object.

      • getOffset

        public void getOffset​(long date,
                      boolean local,
                      int[] offsets)
        TimeZone API.
        Overrides:
        getOffset in class TimeZone
        Parameters:
        date - moment in time for which to return offsets, in units of milliseconds from January 1, 1970 0:00 GMT, either GMT time or local wall time, depending on `local'.
        local - if true, `date' is local wall time; otherwise it is in GMT time.
        offsets - output parameter to receive the raw offset, that is, the offset not including DST adjustments, in offsets[0], and the DST offset, that is, the offset to be added to `rawOffset' to obtain the total offset between local and GMT time, in offsets[1]. If DST is not in effect, the DST offset is zero; otherwise it is a positive value, typically one hour.

      • getOffsetFromLocal

        public void getOffsetFromLocal​(long date,
                               int nonExistingTimeOpt,
                               int duplicatedTimeOpt,
                               int[] offsets)
        Returns time zone offsets from local wall time.
        Overrides:
        getOffsetFromLocal in class BasicTimeZone

      • getRawOffset

        public int getRawOffset()
        Description copied from class: TimeZone
        Gets unmodified offset, NOT modified in case of daylight savings. This is the offset to add *to* UTC to get local time.
        Specified by:
        getRawOffset in class TimeZone
        Returns:
        the unmodified offset to add *to* UTC to get local time.

      • useDaylightTime

        public boolean useDaylightTime()
        Description copied from class: TimeZone
        Queries if this time zone uses daylight savings time.
        Specified by:
        useDaylightTime in class TimeZone
        Returns:
        true if this time zone uses daylight savings time, false, otherwise.

        Note:The default implementation of ICU TimeZone uses the tz database, which supports historic rule changes, for system time zones. With the implementation, there are time zones that used daylight savings time in the past, but no longer used currently. For example, Asia/Tokyo has never used daylight savings time since 1951. Most clients would expect that this method to return false for such case. The default implementation of this method returns true when the time zone uses daylight savings time in the current (Gregorian) calendar year.

      • observesDaylightTime

        public boolean observesDaylightTime()
        Description copied from class: TimeZone
        Queries if this time zone is in daylight saving time or will observe daylight saving time at any future time.

        The default implementation in this class returns true if TimeZone.useDaylightTime() or inDaylightTime(new Date()) returns true.

        Note: This method was added for JDK compatibility support. The JDK's useDaylightTime() only checks the last known rule(s), therefore it may return false even the zone observes daylight saving time currently. JDK added observesDaylightTime() to resolve the issue. In ICU, TimeZone.useDaylightTime() works differently. The ICU implementation checks if the zone uses daylight saving time in the current calendar year. Therefore, it will never return false if daylight saving time is currently used.

        ICU's TimeZone subclass implementations override this method to support the same behavior with JDK's observesDaylightSavingTime(). Unlike TimeZone.useDaylightTime(), the implementation does not take past daylight saving time into account, so that this method may return false even when TimeZone.useDaylightTime() returns true.

        Overrides:
        observesDaylightTime in class TimeZone
        Returns:
        true if this time zone is in daylight saving time or will observe daylight saving time at any future time.
        See Also:
        TimeZone.useDaylightTime()

      • getDSTSavings

        public int getDSTSavings()
        TimeZone API Returns the amount of time to be added to local standard time to get local wall clock time.
        Overrides:
        getDSTSavings in class TimeZone
        Returns:
        the amount of saving time in milliseconds

      • inDaylightTime

        public boolean inDaylightTime​(Date date)
        Description copied from class: TimeZone
        Queries if the given date is in daylight savings time in this time zone.
        Specified by:
        inDaylightTime in class TimeZone
        Parameters:
        date - the given Date.
        Returns:
        true if the given date is in daylight savings time, false, otherwise.

      • hasSameRules

        public boolean hasSameRules​(TimeZone other)
        Description copied from class: TimeZone
        Returns true if this zone has the same rule and offset as another zone. That is, if this zone differs only in ID, if at all. Returns false if the other zone is null.
        Overrides:
        hasSameRules in class TimeZone
        Parameters:
        other - the TimeZone object to be compared with
        Returns:
        true if the other zone is not null and is the same as this one, with the possible exception of the ID

      • getCanonicalID

        public String getCanonicalID()
        Returns the canonical ID of this system time zone

      • setID

        public void setID​(String id)
        Description copied from class: TimeZone
        Sets the time zone ID. This does not change any other data in the time zone object.
        Overrides:
        setID in class TimeZone
        Parameters:
        id - the new time zone ID.

      • toString

        public String toString()
        Description copied from class: Object
        Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression: 
           getClass().getName() + '@' + Integer.toHexString(hashCode())

        See Writing a useful toString method if you intend implementing your own toString method.

        Overrides:
        toString in class Object
        Returns:
        a printable representation of this object.

      • equals

        public boolean equals​(Object obj)
        Description copied from class: TimeZone
        Overrides equals.
        Overrides:
        equals in class TimeZone
        Parameters:
        obj - the object to compare this instance with.
        Returns:
        true if the specified object is equal to this Object; false otherwise.
        See Also:
        Object.hashCode()

      • getNextTransition

        public TimeZoneTransition getNextTransition​(long base,
                                            boolean inclusive)
        Description copied from class: BasicTimeZone
        Returns the first time zone transition after the base time.

        Example code:{@.jcite com.ibm.icu.samples.util.timezone.BasicTimeZoneExample:---getNextTransitionExample}

        Specified by:
        getNextTransition in class BasicTimeZone
        Parameters:
        base - The base time.
        inclusive - Whether the base time is inclusive or not.
        Returns:
        A Date holding the first time zone transition time after the given base time, or null if no time zone transitions are available after the base time.

      • getPreviousTransition

        public TimeZoneTransition getPreviousTransition​(long base,
                                                boolean inclusive)
        Description copied from class: BasicTimeZone
        Returns the last time zone transition before the base time.

        Example code:{@.jcite com.ibm.icu.samples.util.timezone.BasicTimeZoneExample:---getPreviousTransitionExample}

        Specified by:
        getPreviousTransition in class BasicTimeZone
        Parameters:
        base - The base time.
        inclusive - Whether the base time is inclusive or not.
        Returns:
        A Date holding the last time zone transition time before the given base time, or null if no time zone transitions are available before the base time.

      • getTimeZoneRules

        public TimeZoneRule[] getTimeZoneRules()
        Description copied from class: BasicTimeZone
        Returns the array of TimeZoneRule which represents the rule of this time zone object. The first element in the result array will be the InitialTimeZoneRule instance for the initial rule. The rest will be either AnnualTimeZoneRule or TimeArrayTimeZoneRule instances representing transitions.
        Specified by:
        getTimeZoneRules in class BasicTimeZone
        Returns:
        The array of TimeZoneRule which represents this time zone.