Class TimeZone

  • All Implemented Interfaces:
    Freezable<TimeZone>, java.io.Serializable, java.lang.Cloneable
    Direct Known Subclasses:
    BasicTimeZone, JavaTimeZone, TimeZone.ConstantZone, TimeZoneJDK

    public abstract class TimeZone
    extends java.lang.Object
    implements java.io.Serializable, java.lang.Cloneable, Freezable<TimeZone>
    .

    TimeZone represents a time zone offset, and also computes daylight savings.

    Typically, you get a TimeZone using getDefault() which creates a TimeZone based on the time zone where the program is running. For example, for a program running in Japan, getDefault creates a TimeZone object based on Japanese Standard Time.

    You can also get a TimeZone using getTimeZone(String) along with a time zone ID. For instance, the time zone ID for the U.S. Pacific Time zone is "America/Los_Angeles". So, you can get a U.S. Pacific Time TimeZone object with:

     TimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
     
    You can use the getAvailableIDs() method to iterate through all the supported time zone IDs, or getCanonicalID method to check if a time zone ID is supported or not. You can then choose a supported ID to get a TimeZone. If the time zone you want is not represented by one of the supported IDs, then you can create a custom time zone ID with the following syntax:
     GMT[+|-]hh[[:]mm]
     
    For example, you might specify GMT+14:00 as a custom time zone ID. The TimeZone that is returned when you specify a custom time zone ID uses the specified offset from GMT(=UTC) and does not observe daylight saving time. For example, you might specify GMT+14:00 as a custom time zone ID to create a TimeZone representing 14 hours ahead of GMT (with no daylight saving time). In addition, getCanonicalID can also be used to normalize a custom time zone ID.

    For compatibility with JDK 1.1.x, some other three-letter time zone IDs (such as "PST", "CTT", "AST") are also supported. However, their use is deprecated because the same abbreviation is often used for multiple time zones (for example, "CST" could be U.S. "Central Standard Time" and "China Standard Time"), and the Java platform can then only recognize one of them.

    Note: Starting from ICU4J 4.0, you can optionally choose JDK TimeZone as the time zone implementation. The TimeZone factory method getTimeZone creates an instance of ICU's own TimeZone subclass by default. If you want to use the JDK implementation always, you can set the default time zone implementation type by the new method setDefaultTimeZoneType. Alternatively, you can change the initial default implementation type by setting a property below.

     #
     # The default TimeZone implementation type used by the ICU TimeZone
     # factory method. [ ICU | JDK ]
     #
     com.ibm.icu.util.TimeZone.DefaultTimeZoneType = ICU
     

    This property is included in ICUConfig.properties in com.ibm.icu package. When the TimeZone class is loaded, the initialization code checks if the property com.ibm.icu.util.TimeZone.DefaultTimeZoneType=xxx is defined by the system properties. If not available, then it loads ICUConfig.properties to get the default time zone implementation type. The property setting is only used for the initial default value and you can change the default type by calling setDefaultTimeZoneType at runtime.

    See Also:
    Calendar, GregorianCalendar, SimpleTimeZone, Serialized Form
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static TimeZone defaultZone
      The default time zone, or null if not set.
      static int GENERIC_LOCATION
      A style specifier for getDisplayName() indicating a long name derived from the timezone's fallback name, such as "United States (Los Angeles)."
      static TimeZone GMT_ZONE
      The immutable GMT (=UTC) time zone.
      (package private) static java.lang.String GMT_ZONE_ID
      The canonical ID for GMT(UTC) time zone.
      private java.lang.String ID
      The string identifier of this TimeZone.
      private static java.util.logging.Logger LOGGER
      Logger instance for this class
      static int LONG
      A style specifier for getDisplayName() indicating a long name, such as "Pacific Standard Time."
      static int LONG_GENERIC
      A style specifier for getDisplayName() indicating a long generic name, such as "Pacific Time."
      static int LONG_GMT
      A style specifier for getDisplayName() indicating a long name derived from the timezone's offset, such as "GMT-08:00."
      private static long serialVersionUID  
      static int SHORT
      A style specifier for getDisplayName() indicating a short name, such as "PST."
      static int SHORT_COMMONLY_USED
      A style specifier for getDisplayName() indicating a short name derived from the timezone's short standard or daylight timezone name ignoring commonlyUsed, such as "PDT."
      static int SHORT_GENERIC
      A style specifier for getDisplayName() indicating a short generic name, such as "PT."
      static int SHORT_GMT
      A style specifier for getDisplayName() indicating a short name derived from the timezone's offset, such as "-0800."
      static int TIMEZONE_ICU
      A time zone implementation type indicating ICU's own TimeZone used by getTimeZone, setDefaultTimeZoneType and getDefaultTimeZoneType.
      static int TIMEZONE_JDK
      A time zone implementation type indicating the TimeZone used by getTimeZone, setDefaultTimeZoneType and getDefaultTimeZoneType.
      private static int TZ_IMPL
      TimeZone implementation type
      private static java.lang.String TZIMPL_CONFIG_ICU  
      private static java.lang.String TZIMPL_CONFIG_JDK  
      private static java.lang.String TZIMPL_CONFIG_KEY
      TimeZone implementation type initialization
      static TimeZone UNKNOWN_ZONE
      The immutable (frozen) "unknown" time zone.
      static java.lang.String UNKNOWN_ZONE_ID
      The time zone ID reserved for unknown time zone.
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
        TimeZone()
      Default constructor.
      protected TimeZone​(java.lang.String ID)
      Deprecated.
      This API is ICU internal only.
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      private java.lang.String _getDisplayName​(int style, boolean daylight, ULocale locale)
      internal version (which is called by public APIs) accepts SHORT, LONG, SHORT_GENERIC, LONG_GENERIC, SHORT_GMT, LONG_GMT, SHORT_COMMONLY_USED and GENERIC_LOCATION.
      java.lang.Object clone()
      Overrides clone.
      TimeZone cloneAsThawed()
      Provides for the clone operation.
      static int countEquivalentIDs​(java.lang.String id)
      Returns the number of IDs in the equivalency group that includes the given ID.
      boolean equals​(java.lang.Object obj)
      Overrides equals.
      static TimeZone forLocaleOrDefault​(java.util.Locale locale)
      Deprecated.
      This API is ICU internal only.
      static TimeZone forULocaleOrDefault​(ULocale locale)
      Deprecated.
      This API is ICU internal only.
      TimeZone freeze()
      Freezes the object.
      static java.lang.String[] getAvailableIDs()
      Return a new String array containing all system TimeZone IDs.
      static java.lang.String[] getAvailableIDs​(int rawOffset)
      Return a new String array containing all system TimeZone IDs with the given raw offset from GMT.
      static java.util.Set<java.lang.String> getAvailableIDs​(TimeZone.SystemTimeZoneType zoneType, java.lang.String region, java.lang.Integer rawOffset)
      Returns a set of time zone ID strings with the given filter conditions.
      static java.lang.String[] getAvailableIDs​(java.lang.String country)
      Return a new String array containing all system TimeZone IDs associated with the given country.
      static java.lang.String getCanonicalID​(java.lang.String id)
      Returns the canonical system time zone ID or the normalized custom time zone ID for the given time zone ID.
      static java.lang.String getCanonicalID​(java.lang.String id, boolean[] isSystemID)
      Returns the canonical system time zone ID or the normalized custom time zone ID for the given time zone ID.
      static TimeZone getDefault()
      Gets the default TimeZone for this host.
      static int getDefaultTimeZoneType()
      Returns the default time zone type currently used.
      java.lang.String getDisplayName()
      Returns a name of this time zone suitable for presentation to the user in the default DISPLAY locale.
      java.lang.String getDisplayName​(boolean daylight, int style)
      Returns a name of this time zone suitable for presentation to the user in the default DISPLAY locale.
      java.lang.String getDisplayName​(boolean daylight, int style, ULocale locale)
      Returns a name of this time zone suitable for presentation to the user in the specified locale.
      java.lang.String getDisplayName​(boolean daylight, int style, java.util.Locale locale)
      Returns a name of this time zone suitable for presentation to the user in the specified locale.
      java.lang.String getDisplayName​(ULocale locale)
      Returns a name of this time zone suitable for presentation to the user in the specified locale.
      java.lang.String getDisplayName​(java.util.Locale locale)
      Returns a name of this time zone suitable for presentation to the user in the specified locale.
      int getDSTSavings()
      Returns the amount of time to be added to local standard time to get local wall clock time.
      static java.lang.String getEquivalentID​(java.lang.String id, int index)
      Returns an ID in the equivalency group that includes the given ID.
      (package private) static BasicTimeZone getFrozenICUTimeZone​(java.lang.String id, boolean trySystem)
      Returns a frozen ICU type TimeZone object given a time zone ID.
      static TimeZone getFrozenTimeZone​(java.lang.String ID)
      Gets the TimeZone for the given ID.
      static java.lang.String getIanaID​(java.lang.String id)
      Returns the preferred time zone ID in the IANA database for the given time zone ID.
      java.lang.String getID()
      Gets the ID of this time zone.
      static java.lang.String getIDForWindowsID​(java.lang.String winid, java.lang.String region)
      Converts a Windows time zone ID to an equivalent system time zone ID for a region.
      abstract int getOffset​(int era, int year, int month, int day, int dayOfWeek, int milliseconds)
      Gets the time zone offset, for current date, modified in case of daylight savings.
      int getOffset​(long date)
      Returns the offset of this time zone from UTC at the specified date.
      void getOffset​(long date, boolean local, int[] offsets)
      Returns the time zone raw and GMT offset for the given moment in time.
      abstract int getRawOffset()
      Gets unmodified offset, NOT modified in case of daylight savings.
      static java.lang.String getRegion​(java.lang.String id)
      Returns the region code associated with the given system time zone ID.
      static TimeZone getTimeZone​(java.lang.String ID)
      Gets the TimeZone for the given ID.
      static TimeZone getTimeZone​(java.lang.String ID, int type)
      Gets the TimeZone for the given ID and the timezone type.
      private static TimeZone getTimeZone​(java.lang.String id, int type, boolean frozen)
      Gets the TimeZone for the given ID and the timezone type.
      static java.lang.String getTZDataVersion()
      Returns the time zone data version currently used by ICU.
      static java.lang.String getWindowsID​(java.lang.String id)
      Converts a system time zone ID to an equivalent Windows time zone ID.
      int hashCode()
      Overrides hashCode.
      boolean hasSameRules​(TimeZone other)
      Returns true if this zone has the same rule and offset as another zone.
      abstract boolean inDaylightTime​(java.util.Date date)
      Queries if the given date is in daylight savings time in this time zone.
      boolean isFrozen()
      Determines whether the object has been frozen or not.
      boolean observesDaylightTime()
      Queries if this time zone is in daylight saving time or will observe daylight saving time at any future time.
      static void setDefault​(TimeZone tz)
      Sets the TimeZone that is returned by the getDefault method.
      static void setDefaultTimeZoneType​(int type)
      Sets the default time zone type used by getTimeZone.
      static void setICUDefault​(TimeZone tz)
      Deprecated.
      This API is ICU internal only.
      void setID​(java.lang.String ID)
      Sets the time zone ID.
      abstract void setRawOffset​(int offsetMillis)
      Sets the base time zone offset to GMT.
      abstract boolean useDaylightTime()
      Queries if this time zone uses daylight savings time.
      • Methods inherited from class java.lang.Object

        finalize, getClass, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • LOGGER

        private static final java.util.logging.Logger LOGGER
        Logger instance for this class
      • TIMEZONE_ICU

        public static final int TIMEZONE_ICU
        A time zone implementation type indicating ICU's own TimeZone used by getTimeZone, setDefaultTimeZoneType and getDefaultTimeZoneType.
        See Also:
        Constant Field Values
      • TIMEZONE_JDK

        public static final int TIMEZONE_JDK
        A time zone implementation type indicating the TimeZone used by getTimeZone, setDefaultTimeZoneType and getDefaultTimeZoneType.
        See Also:
        Constant Field Values
      • SHORT

        public static final int SHORT
        A style specifier for getDisplayName() indicating a short name, such as "PST."
        See Also:
        LONG, Constant Field Values
      • LONG

        public static final int LONG
        A style specifier for getDisplayName() indicating a long name, such as "Pacific Standard Time."
        See Also:
        SHORT, Constant Field Values
      • SHORT_GENERIC

        public static final int SHORT_GENERIC
        A style specifier for getDisplayName() indicating a short generic name, such as "PT."
        See Also:
        LONG_GENERIC, Constant Field Values
      • LONG_GENERIC

        public static final int LONG_GENERIC
        A style specifier for getDisplayName() indicating a long generic name, such as "Pacific Time."
        See Also:
        SHORT_GENERIC, Constant Field Values
      • SHORT_GMT

        public static final int SHORT_GMT
        A style specifier for getDisplayName() indicating a short name derived from the timezone's offset, such as "-0800."
        See Also:
        LONG_GMT, Constant Field Values
      • LONG_GMT

        public static final int LONG_GMT
        A style specifier for getDisplayName() indicating a long name derived from the timezone's offset, such as "GMT-08:00."
        See Also:
        SHORT_GMT, Constant Field Values
      • SHORT_COMMONLY_USED

        public static final int SHORT_COMMONLY_USED
        A style specifier for getDisplayName() indicating a short name derived from the timezone's short standard or daylight timezone name ignoring commonlyUsed, such as "PDT."
        See Also:
        Constant Field Values
      • GENERIC_LOCATION

        public static final int GENERIC_LOCATION
        A style specifier for getDisplayName() indicating a long name derived from the timezone's fallback name, such as "United States (Los Angeles)."
        See Also:
        Constant Field Values
      • GMT_ZONE_ID

        static final java.lang.String GMT_ZONE_ID
        The canonical ID for GMT(UTC) time zone.
        See Also:
        Constant Field Values
      • UNKNOWN_ZONE

        public static final TimeZone UNKNOWN_ZONE
        The immutable (frozen) "unknown" time zone. It behaves like the GMT/UTC time zone but has the UNKNOWN_ZONE_ID = "Etc/Unknown". getTimeZone(String) returns a mutable clone of this time zone if the input ID is not recognized.
        See Also:
        UNKNOWN_ZONE_ID, getTimeZone(String)
      • GMT_ZONE

        public static final TimeZone GMT_ZONE
        The immutable GMT (=UTC) time zone. Its ID is "Etc/GMT".
      • ID

        private java.lang.String ID
        The string identifier of this TimeZone. This is a programmatic identifier used internally to look up TimeZone objects from the system table and also to map them to their localized display names. ID values are unique in the system table but may not be for dynamically created zones.
      • defaultZone

        private static volatile TimeZone defaultZone
        The default time zone, or null if not set.
      • TZ_IMPL

        private static int TZ_IMPL
        TimeZone implementation type
      • TZIMPL_CONFIG_KEY

        private static final java.lang.String TZIMPL_CONFIG_KEY
        TimeZone implementation type initialization
        See Also:
        Constant Field Values
      • TZIMPL_CONFIG_ICU

        private static final java.lang.String TZIMPL_CONFIG_ICU
        See Also:
        Constant Field Values
      • TZIMPL_CONFIG_JDK

        private static final java.lang.String TZIMPL_CONFIG_JDK
        See Also:
        Constant Field Values
    • Constructor Detail

      • TimeZone

        public TimeZone()
        Default constructor. (For invocation by subclass constructors, typically implicit.)
      • TimeZone

        @Deprecated
        protected TimeZone​(java.lang.String ID)
        Deprecated.
        This API is ICU internal only.
        Constructing a TimeZone with the given time zone ID.
        Parameters:
        ID - the time zone ID.
    • Method Detail

      • getOffset

        public abstract int getOffset​(int era,
                                      int year,
                                      int month,
                                      int day,
                                      int dayOfWeek,
                                      int milliseconds)
        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.
        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​(long date)
        Returns the offset of this time zone from UTC at the specified date. If Daylight Saving Time is in effect at the specified date, the offset value is adjusted with the amount of daylight saving.
        Parameters:
        date - the date represented in milliseconds since January 1, 1970 00:00:00 GMT
        Returns:
        the amount of time in milliseconds to add to UTC to get local time.
        See Also:
        Calendar.ZONE_OFFSET, Calendar.DST_OFFSET, getOffset(long, boolean, int[])
      • getOffset

        public void getOffset​(long date,
                              boolean local,
                              int[] offsets)
        Returns the time zone raw and GMT offset for the given moment in time. Upon return, local-millis = GMT-millis + rawOffset + dstOffset. All computations are performed in the proleptic Gregorian calendar. The default implementation in the TimeZone class delegates to the 8-argument getOffset().
        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.
      • setRawOffset

        public abstract void setRawOffset​(int offsetMillis)
        Sets the base time zone offset to GMT. This is the offset to add to UTC to get local time.
        Parameters:
        offsetMillis - the given base time zone offset to GMT.
      • getRawOffset

        public abstract int getRawOffset()
        Gets unmodified offset, NOT modified in case of daylight savings. This is the offset to add to UTC to get local time.
        Returns:
        the unmodified offset to add to UTC to get local time.
      • getID

        public java.lang.String getID()
        Gets the ID of this time zone.
        Returns:
        the ID of this time zone.
      • setID

        public void setID​(java.lang.String ID)
        Sets the time zone ID. This does not change any other data in the time zone object.
        Parameters:
        ID - the new time zone ID.
      • getDisplayName

        public final java.lang.String getDisplayName()
        Returns a name of this time zone suitable for presentation to the user in the default DISPLAY locale. This method returns the long generic name. If the display name is not available for the locale, a fallback based on the country, city, or time zone id will be used.
        Returns:
        the human-readable name of this time zone in the default locale.
        See Also:
        ULocale.Category.DISPLAY
      • getDisplayName

        public final java.lang.String getDisplayName​(java.util.Locale locale)
        Returns a name of this time zone suitable for presentation to the user in the specified locale. This method returns the long generic name. If the display name is not available for the locale, a fallback based on the country, city, or time zone id will be used.
        Parameters:
        locale - the locale in which to supply the display name.
        Returns:
        the human-readable name of this time zone in the given locale or in the default locale if the given locale is not recognized.
      • getDisplayName

        public final java.lang.String getDisplayName​(ULocale locale)
        Returns a name of this time zone suitable for presentation to the user in the specified locale. This method returns the long name, not including daylight savings. If the display name is not available for the locale, a fallback based on the country, city, or time zone id will be used.
        Parameters:
        locale - the ulocale in which to supply the display name.
        Returns:
        the human-readable name of this time zone in the given locale or in the default ulocale if the given ulocale is not recognized.
      • getDisplayName

        public final java.lang.String getDisplayName​(boolean daylight,
                                                     int style)
        Returns a name of this time zone suitable for presentation to the user in the default DISPLAY locale. If the display name is not available for the locale, then this method returns a string in the localized GMT offset format such as GMT[+-]HH:mm.
        Parameters:
        daylight - if true, return the daylight savings name.
        style - the output style of the display name. Valid styles are SHORT, LONG, SHORT_GENERIC, LONG_GENERIC, SHORT_GMT, LONG_GMT, SHORT_COMMONLY_USED or GENERIC_LOCATION.
        Returns:
        the human-readable name of this time zone in the default locale.
        See Also:
        ULocale.Category.DISPLAY
      • getDisplayName

        public java.lang.String getDisplayName​(boolean daylight,
                                               int style,
                                               java.util.Locale locale)
        Returns a name of this time zone suitable for presentation to the user in the specified locale. If the display name is not available for the locale, then this method returns a string in the localized GMT offset format such as GMT[+-]HH:mm.
        Parameters:
        daylight - if true, return the daylight savings name.
        style - the output style of the display name. Valid styles are SHORT, LONG, SHORT_GENERIC, LONG_GENERIC, SHORT_GMT, LONG_GMT, SHORT_COMMONLY_USED or GENERIC_LOCATION.
        locale - the locale in which to supply the display name.
        Returns:
        the human-readable name of this time zone in the given locale or in the default locale if the given locale is not recognized.
        Throws:
        java.lang.IllegalArgumentException - style is invalid.
      • getDisplayName

        public java.lang.String getDisplayName​(boolean daylight,
                                               int style,
                                               ULocale locale)
        Returns a name of this time zone suitable for presentation to the user in the specified locale. If the display name is not available for the locale, then this method returns a string in the localized GMT offset format such as GMT[+-]HH:mm.
        Parameters:
        daylight - if true, return the daylight savings name.
        style - the output style of the display name. Valid styles are SHORT, LONG, SHORT_GENERIC, LONG_GENERIC, SHORT_GMT, LONG_GMT, SHORT_COMMONLY_USED or GENERIC_LOCATION.
        locale - the locale in which to supply the display name.
        Returns:
        the human-readable name of this time zone in the given locale or in the default locale if the given locale is not recognized.
        Throws:
        java.lang.IllegalArgumentException - style is invalid.
      • _getDisplayName

        private java.lang.String _getDisplayName​(int style,
                                                 boolean daylight,
                                                 ULocale locale)
        internal version (which is called by public APIs) accepts SHORT, LONG, SHORT_GENERIC, LONG_GENERIC, SHORT_GMT, LONG_GMT, SHORT_COMMONLY_USED and GENERIC_LOCATION.
      • getDSTSavings

        public int getDSTSavings()
        Returns the amount of time to be added to local standard time to get local wall clock time.

        The default implementation always returns 3600000 milliseconds (i.e., one hour) if this time zone observes Daylight Saving Time. Otherwise, 0 (zero) is returned.

        If an underlying TimeZone implementation subclass supports historical Daylight Saving Time changes, this method returns the known latest daylight saving value.

        Returns:
        the amount of saving time in milliseconds
      • useDaylightTime

        public abstract boolean useDaylightTime()
        Queries if this time zone uses daylight savings time.
        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()
        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 useDaylightTime() or inDaylightTime(new Date()) returns true.

        Note: This method was added for TimeZone compatibility support. The TimeZone.useDaylightTime() method only checks the last known rule(s), therefore it may return false even the zone observes daylight saving time currently. TimeZone added observesDaylightTime() to resolve the issue. In ICU, 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 TimeZone.observesDaylightTime(). Unlike useDaylightTime(), the implementation does not take past daylight saving time into account, so that this method may return false even when useDaylightTime() returns true.

        Returns:
        true if this time zone is in daylight saving time or will observe daylight saving time at any future time.
        See Also:
        useDaylightTime()
      • inDaylightTime

        public abstract boolean inDaylightTime​(java.util.Date date)
        Queries if the given date is in daylight savings time in this time zone.
        Parameters:
        date - the given Date.
        Returns:
        true if the given date is in daylight savings time, false, otherwise.
      • getTimeZone

        public static TimeZone getTimeZone​(java.lang.String ID)
        Gets the TimeZone for the given ID.
        Parameters:
        ID - the ID for a TimeZone, such as "America/Los_Angeles", or a custom ID such as "GMT-8:00". Note that the support of abbreviations, such as "PST", is for JDK 1.1.x compatibility only and full names should be used.
        Returns:
        the specified TimeZone, or a mutable clone of the UNKNOWN_ZONE if the given ID cannot be understood or if the given ID is "Etc/Unknown".
        See Also:
        UNKNOWN_ZONE
      • getFrozenTimeZone

        public static TimeZone getFrozenTimeZone​(java.lang.String ID)
        Gets the TimeZone for the given ID. The instance of TimeZone returned by this method is immutable. Any methods mutate the instance(setID(String), setRawOffset(int)) will throw UnsupportedOperationException upon its invocation.
        Parameters:
        ID - the ID for a TimeZone, such as "America/Los_Angeles", or a custom ID such as "GMT-8:00". Note that the support of abbreviations, such as "PST", is for JDK 1.1.x compatibility only and full names should be used.
        Returns:
        the specified TimeZone, or the UNKNOWN_ZONE if the given ID cannot be understood.
        See Also:
        UNKNOWN_ZONE
      • getTimeZone

        public static TimeZone getTimeZone​(java.lang.String ID,
                                           int type)
        Gets the TimeZone for the given ID and the timezone type.
        Parameters:
        ID - the ID for a TimeZone, such as "America/Los_Angeles", or a custom ID such as "GMT-8:00". Note that the support of abbreviations, such as "PST", is for JDK 1.1.x compatibility only and full names should be used.
        type - Time zone type, either TIMEZONE_ICU or TIMEZONE_JDK.
        Returns:
        the specified TimeZone, or a mutable clone of the UNKNOWN_ZONE if the given ID cannot be understood or if the given ID is "Etc/Unknown".
        See Also:
        UNKNOWN_ZONE
      • getTimeZone

        private static TimeZone getTimeZone​(java.lang.String id,
                                            int type,
                                            boolean frozen)
        Gets the TimeZone for the given ID and the timezone type.
        Parameters:
        id - time zone ID
        type - time zone implementation type, TIMEZONE_JDK or TIMEZONE_ICU
        frozen - specify if the returned object can be frozen
        Returns:
        the specified TimeZone or UNKNOWN_ZONE if the given ID cannot be understood.
      • getFrozenICUTimeZone

        static BasicTimeZone getFrozenICUTimeZone​(java.lang.String id,
                                                  boolean trySystem)
        Returns a frozen ICU type TimeZone object given a time zone ID.
        Parameters:
        id - the time zone ID
        trySystem - if true tries the system time zones first otherwise skip to the custom time zones.
        Returns:
        the frozen ICU TimeZone or null if one could not be created.
      • setDefaultTimeZoneType

        public static void setDefaultTimeZoneType​(int type)
        Sets the default time zone type used by getTimeZone.
        Parameters:
        type - time zone type, either TIMEZONE_ICU or TIMEZONE_JDK.
      • getDefaultTimeZoneType

        public static int getDefaultTimeZoneType()
        Returns the default time zone type currently used.
        Returns:
        The default time zone type, either TIMEZONE_ICU or TIMEZONE_JDK.
      • getAvailableIDs

        public static java.util.Set<java.lang.String> getAvailableIDs​(TimeZone.SystemTimeZoneType zoneType,
                                                                      java.lang.String region,
                                                                      java.lang.Integer rawOffset)
        Returns a set of time zone ID strings with the given filter conditions.

        Note:A Set returned by this method is immutable.

        Parameters:
        zoneType - The system time zone type.
        region - The ISO 3166 two-letter country code or UN M.49 three-digit area code. When null, no filtering done by region.
        rawOffset - An offset from GMT in milliseconds, ignoring the effect of daylight savings time, if any. When null, no filtering done by zone offset.
        Returns:
        an immutable set of system time zone IDs.
        See Also:
        TimeZone.SystemTimeZoneType
      • getAvailableIDs

        public static java.lang.String[] getAvailableIDs​(int rawOffset)
        Return a new String array containing all system TimeZone IDs with the given raw offset from GMT. These IDs may be passed to get() to construct the corresponding TimeZone object.
        Parameters:
        rawOffset - the offset in milliseconds from GMT
        Returns:
        an array of IDs for system TimeZones with the given raw offset. If there are none, return a zero-length array.
        See Also:
        getAvailableIDs(SystemTimeZoneType, String, Integer)
      • getAvailableIDs

        public static java.lang.String[] getAvailableIDs​(java.lang.String country)
        Return a new String array containing all system TimeZone IDs associated with the given country. These IDs may be passed to get() to construct the corresponding TimeZone object.
        Parameters:
        country - a two-letter ISO 3166 country code, or null to return zones not associated with any country
        Returns:
        an array of IDs for system TimeZones in the given country. If there are none, return a zero-length array.
        See Also:
        getAvailableIDs(SystemTimeZoneType, String, Integer)
      • getAvailableIDs

        public static java.lang.String[] getAvailableIDs()
        Return a new String array containing all system TimeZone IDs. These IDs (and only these IDs) may be passed to get() to construct the corresponding TimeZone object.
        Returns:
        an array of all system TimeZone IDs
        See Also:
        getAvailableIDs(SystemTimeZoneType, String, Integer)
      • countEquivalentIDs

        public static int countEquivalentIDs​(java.lang.String id)
        Returns the number of IDs in the equivalency group that includes the given ID. An equivalency group contains zones that have the same GMT offset and rules.

        The returned count includes the given ID; it is always >= 1 for valid IDs. The given ID must be a system time zone. If it is not, returns zero.

        Parameters:
        id - a system time zone ID
        Returns:
        the number of zones in the equivalency group containing 'id', or zero if 'id' is not a valid system ID
        See Also:
        getEquivalentID(java.lang.String, int)
      • getEquivalentID

        public static java.lang.String getEquivalentID​(java.lang.String id,
                                                       int index)
        Returns an ID in the equivalency group that includes the given ID. An equivalency group contains zones that have the same GMT offset and rules.

        The given index must be in the range 0..n-1, where n is the value returned by countEquivalentIDs(id). For some value of 'index', the returned value will be equal to the given id. If the given id is not a valid system time zone, or if 'index' is out of range, then returns an empty string.

        Parameters:
        id - a system time zone ID
        index - a value from 0 to n-1, where n is the value returned by countEquivalentIDs(id)
        Returns:
        the ID of the index-th zone in the equivalency group containing 'id', or an empty string if 'id' is not a valid system ID or 'index' is out of range
        See Also:
        countEquivalentIDs(java.lang.String)
      • forULocaleOrDefault

        @Deprecated
        public static TimeZone forULocaleOrDefault​(ULocale locale)
        Deprecated.
        This API is ICU internal only.
        If the locale contains the timezone keyword, creates a copy of that TimeZone. Otherwise, create the default TimeZone.
        Parameters:
        locale - a locale which may contains 'timezone' keyword/value.
        Returns:
        A TimeZone. Clients are responsible for deleting the TimeZone object returned.
      • forLocaleOrDefault

        @Deprecated
        public static TimeZone forLocaleOrDefault​(java.util.Locale locale)
        Deprecated.
        This API is ICU internal only.
        If the locale contains the timezone keyword, creates a copy of that TimeZone. Otherwise, create the default TimeZone.
        Parameters:
        locale - a locale which may contains 'timezone' keyword/value.
        Returns:
        A TimeZone. Clients are responsible for deleting the TimeZone object returned.
      • getDefault

        public static TimeZone getDefault()
        Gets the default TimeZone for this host. The source of the default TimeZone may vary with implementation.
        Returns:
        a default TimeZone.
      • setDefault

        public static void setDefault​(TimeZone tz)
        Sets the TimeZone that is returned by the getDefault method. This method also sets a Java TimeZone equivalent to the input tz as the JVM's default time zone if not null. If tz is null, next getDefault() method invocation will reset the default time zone synchronized with the JVM's default at that time.
        Parameters:
        tz - the new default time zone
      • setICUDefault

        @Deprecated
        public static void setICUDefault​(TimeZone tz)
        Deprecated.
        This API is ICU internal only.
        Sets the TimeZone that is returned by the getDefault method. If tz is null, next getDefault() method invocation will reset the default time zone synchronized with the JVM's default at that time. Unlike setDefault(TimeZone), this method does not change the JVM's default time zone.
        Parameters:
        tz - the new default time zone
      • hasSameRules

        public boolean hasSameRules​(TimeZone other)
        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.
        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
      • clone

        public java.lang.Object clone()
        Overrides clone.
        Overrides:
        clone in class java.lang.Object
      • equals

        public boolean equals​(java.lang.Object obj)
        Overrides equals.
        Overrides:
        equals in class java.lang.Object
        Returns:
        true if this object is the same as the obj argument; false otherwise.
      • hashCode

        public int hashCode()
        Overrides hashCode.
        Overrides:
        hashCode in class java.lang.Object
        Returns:
        a hash code value for this object.
      • getTZDataVersion

        public static java.lang.String getTZDataVersion()
        Returns the time zone data version currently used by ICU.
        Returns:
        the version string, such as "2007f"
        Throws:
        java.util.MissingResourceException - if ICU time zone resource bundle is missing or the version information is not available.
      • getCanonicalID

        public static java.lang.String getCanonicalID​(java.lang.String id)
        Returns the canonical system time zone ID or the normalized custom time zone ID for the given time zone ID.
        Parameters:
        id - The input time zone ID to be canonicalized.
        Returns:
        The canonical system time zone ID or the custom time zone ID in normalized format for the given time zone ID. When the given time zone ID is neither a known system time zone ID nor a valid custom time zone ID, null is returned.
      • getCanonicalID

        public static java.lang.String getCanonicalID​(java.lang.String id,
                                                      boolean[] isSystemID)
        Returns the canonical system time zone ID or the normalized custom time zone ID for the given time zone ID.
        Parameters:
        id - The input time zone ID to be canonicalized.
        isSystemID - When non-null boolean array is specified and the given ID is a known system time zone ID, true is set to isSystemID[0]
        Returns:
        The canonical system time zone ID or the custom time zone ID in normalized format for the given time zone ID. When the given time zone ID is neither a known system time zone ID nor a valid custom time zone ID, null is returned.
      • getIanaID

        public static java.lang.String getIanaID​(java.lang.String id)
        Returns the preferred time zone ID in the IANA database for the given time zone ID. There are two types of preferred IDs. The first type is the one defined in zone.tab file, such as "America/Los_Angeles". The second types is the one defined for zones not associated with a specific region, but not defined with "Link" syntax, such as "Etc/GMT+10".

        Note: For most of system time zone IDs, this method returns an ID same as getCanonicalID(String). getCanonicalID(String) is based on canonical time zone IDs defined in Unicode CLDR. These canonical time zone IDs in CLDR were based on very old version of the time zone database. In the IANA time zone database, some IDs were updated since then. This API returns a newer time zone ID. For example, CLDR defines "Asia/Calcutta" as the canonical time zone ID. This method returns "Asia/Kolkata" instead.

        "Etc/Unknown" is a special time zone ID defined by CLDR. There are no corresponding zones in the IANA time zone database. when the input is "Etc/Unknown", this method returns "Etc/Unknown", but it really means no mappings available. Caller of this method should interpret "Etc/Unknown" as an error.

        Parameters:
        id - The input time zone ID.
        Returns:
        The preferred time zone ID in the IANA time zone database, or UNKNOWN_ZONE_ID if the input ID is not a system ID.
        See Also:
        getCanonicalID(String)
      • getRegion

        public static java.lang.String getRegion​(java.lang.String id)
        Returns the region code associated with the given system time zone ID. The region code is either ISO 3166 2-letter country code or UN M.49 3-digit area code. When the time zone is not associated with a specific location, for example - "Etc/UTC", "EST5EDT", then this method returns "001" (UN M.49 area code for World).
        Parameters:
        id - the system time zone ID.
        Returns:
        the region code associated with the given system time zone ID.
        Throws:
        java.lang.IllegalArgumentException - if id is not a known system ID.
        See Also:
        getAvailableIDs(String)
      • getWindowsID

        public static java.lang.String getWindowsID​(java.lang.String id)
        Converts a system time zone ID to an equivalent Windows time zone ID. For example, Windows time zone ID "Pacific Standard Time" is returned for input "America/Los_Angeles".

        There are system time zones that cannot be mapped to Windows zones. When the input system time zone ID is unknown or unmappable to a Windows time zone, then this method returns null.

        This implementation utilizes Zone-Tzid mapping data. The mapping data is updated time to time. To get the latest changes, please read the ICU user guide section Updating the Time Zone Data.

        Parameters:
        id - A system time zone ID
        Returns:
        A Windows time zone ID mapped from the input system time zone ID, or null when the input ID is unknown or unmappable.
        See Also:
        getIDForWindowsID(String, String)
      • getIDForWindowsID

        public static java.lang.String getIDForWindowsID​(java.lang.String winid,
                                                         java.lang.String region)
        Converts a Windows time zone ID to an equivalent system time zone ID for a region. For example, system time zone ID "America/Los_Angeles" is returned for input Windows ID "Pacific Standard Time" and region "US" (or null), "America/Vancouver" is returned for the same Windows ID "Pacific Standard Time" and region "CA".

        Not all Windows time zones can be mapped to system time zones. When the input Windows time zone ID is unknown or unmappable to a system time zone, then this method returns null.

        This implementation utilizes Zone-Tzid mapping data. The mapping data is updated time to time. To get the latest changes, please read the ICU user guide section Updating the Time Zone Data.

        Parameters:
        winid - A Windows time zone ID
        region - A region code, or null if no regional preference.
        Returns:
        A system time zone ID mapped from the input Windows time zone ID, or null when the input ID is unknown or unmappable.
        See Also:
        getWindowsID(String)
      • isFrozen

        public boolean isFrozen()
        Determines whether the object has been frozen or not.
        Specified by:
        isFrozen in interface Freezable<TimeZone>