Package java.util

Class TimeZone

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int LONG
      The long display name style, such as Pacific Daylight Time.
      static int SHORT
      The short display name style, such as PDT.
    • Constructor Summary

      Constructors 
      Constructor Description
      TimeZone()  
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      Object clone()
      Returns a new time zone with the same ID, raw offset, and daylight savings time rules as this time zone.
      static String createGmtOffsetString​(boolean includeGmt, boolean includeMinuteSeparator, int offsetMillis)
      Returns a string representation of an offset from UTC.
      static String[] getAvailableIDs()
      Returns the system's installed time zone IDs.
      static String[] getAvailableIDs​(int offsetMillis)
      Returns the IDs of the time zones whose offset from UTC is offsetMillis.
      static TimeZone getDefault()
      Returns the user's preferred time zone.
      String getDisplayName()
      Equivalent to getDisplayName(false, TimeZone.LONG, Locale.getDefault()).
      String getDisplayName​(boolean daylightTime, int style)
      Equivalent to getDisplayName(daylightTime, style, Locale.getDefault()).
      String getDisplayName​(boolean daylightTime, int style, Locale locale)
      Returns the short or long name of this time zone with either standard or daylight time, as written in locale.
      String getDisplayName​(Locale locale)
      Equivalent to getDisplayName(false, TimeZone.LONG, locale).
      int getDSTSavings()
      Returns the latest daylight savings in milliseconds for this time zone, relative to this time zone's regular UTC offset (as returned by getRawOffset()).
      String getID()
      Returns the ID of this TimeZone, such as America/Los_Angeles, GMT-08:00 or UTC.
      abstract int getOffset​(int era, int year, int month, int day, int dayOfWeek, int timeOfDayMillis)
      Returns this time zone's offset in milliseconds from UTC at the specified date and time.
      int getOffset​(long time)
      Returns the offset in milliseconds from UTC for this time zone at time.
      abstract int getRawOffset()
      Returns the offset in milliseconds from UTC of this time zone's standard time.
      static TimeZone getTimeZone​(String id)
      Returns a TimeZone corresponding to the given id, or GMT for unknown ids.
      boolean hasSameRules​(TimeZone timeZone)
      Returns true if timeZone has the same rules as this time zone.
      abstract boolean inDaylightTime​(Date time)
      Returns true if time is in a daylight savings time period for this time zone.
      static void setDefault​(TimeZone timeZone)
      Overrides the default time zone for the current process only.
      void setID​(String id)
      Sets the ID of this TimeZone.
      abstract void setRawOffset​(int offsetMillis)
      Sets the offset in milliseconds from UTC of this time zone's standard time.
      abstract boolean useDaylightTime()
      Returns true if this time zone has a future transition to or from daylight savings time.
    • Field Detail

      • SHORT

        public static final int SHORT
        The short display name style, such as PDT. Requests for this style may yield GMT offsets like GMT-08:00.
        See Also:
        Constant Field Values
      • LONG

        public static final int LONG
        The long display name style, such as Pacific Daylight Time. Requests for this style may yield GMT offsets like GMT-08:00.
        See Also:
        Constant Field Values
    • Constructor Detail

      • TimeZone

        public TimeZone()
    • Method Detail

      • clone

        public Object clone()
        Returns a new time zone with the same ID, raw offset, and daylight savings time rules as this time zone.
        Overrides:
        clone in class Object
        Returns:
        a copy of this object.
      • getAvailableIDs

        public static String[] getAvailableIDs()
        Returns the system's installed time zone IDs. Any of these IDs can be passed to getTimeZone(java.lang.String) to lookup the corresponding time zone instance.
      • getAvailableIDs

        public static String[] getAvailableIDs​(int offsetMillis)
        Returns the IDs of the time zones whose offset from UTC is offsetMillis. Any of these IDs can be passed to getTimeZone(java.lang.String) to lookup the corresponding time zone instance.
        Returns:
        a possibly-empty array.
      • getDefault

        public static TimeZone getDefault()
        Returns the user's preferred time zone. This may have been overridden for this process with setDefault(java.util.TimeZone).

        Since the user's time zone changes dynamically, avoid caching this value. Instead, use this method to look it up for each use.

      • getDisplayName

        public final String getDisplayName​(Locale locale)
        Equivalent to getDisplayName(false, TimeZone.LONG, locale).
      • getDisplayName

        public final String getDisplayName​(boolean daylightTime,
                                           int style)
        Equivalent to getDisplayName(daylightTime, style, Locale.getDefault()). Be wary of the default locale.
      • getDisplayName

        public String getDisplayName​(boolean daylightTime,
                                     int style,
                                     Locale locale)
        Returns the short or long name of this time zone with either standard or daylight time, as written in locale. If the name is not available, the result is in the format GMT[+-]hh:mm.
        Parameters:
        daylightTime - true for daylight time, false for standard time.
        style - either LONG or SHORT.
        locale - the display locale.
      • createGmtOffsetString

        public static String createGmtOffsetString​(boolean includeGmt,
                                                   boolean includeMinuteSeparator,
                                                   int offsetMillis)
        Returns a string representation of an offset from UTC.

        The format is "[GMT](+|-)HH[:]MM". The output is not localized.

        Parameters:
        includeGmt - true to include "GMT", false to exclude
        includeMinuteSeparator - true to include the separator between hours and minutes, false to exclude.
        offsetMillis - the offset from UTC
      • getID

        public String getID()
        Returns the ID of this TimeZone, such as America/Los_Angeles, GMT-08:00 or UTC.
      • getDSTSavings

        public int getDSTSavings()
        Returns the latest daylight savings in milliseconds for this time zone, relative to this time zone's regular UTC offset (as returned by getRawOffset()).

        This class returns 3600000 (1 hour) for time zones that use daylight savings time and 0 for timezones that do not, leaving it to subclasses to override this method for other daylight savings offsets. (There are time zones, such as Australia/Lord_Howe, that use other values.)

        Note that this method doesn't tell you whether or not to apply the offset: you need to call inDaylightTime for the specific time you're interested in. If this method returns a non-zero offset, that only tells you that this TimeZone sometimes observes daylight savings.

        Note also that this method doesn't necessarily return the value you need to apply to the time you're working with. This value can and does change over time for a given time zone.

        It's highly unlikely that you should ever call this method. You probably want getOffset(long) instead, which tells you the offset for a specific point in time, and takes daylight savings into account for you.

      • getOffset

        public int getOffset​(long time)
        Returns the offset in milliseconds from UTC for this time zone at time. The offset includes daylight savings time if the specified date is within the daylight savings time period.
        Parameters:
        time - the date in milliseconds since January 1, 1970 00:00:00 UTC
      • getOffset

        public abstract int getOffset​(int era,
                                      int year,
                                      int month,
                                      int day,
                                      int dayOfWeek,
                                      int timeOfDayMillis)
        Returns this time zone's offset in milliseconds from UTC at the specified date and time. The offset includes daylight savings time if the date and time is within the daylight savings time period.

        This method is intended to be used by Calendar to compute Calendar.DST_OFFSET and Calendar.ZONE_OFFSET. Application code should have no reason to call this method directly. Each parameter is interpreted in the same way as the corresponding Calendar field. Refer to Calendar for specific definitions of this method's parameters.

      • getRawOffset

        public abstract int getRawOffset()
        Returns the offset in milliseconds from UTC of this time zone's standard time.
      • getTimeZone

        public static TimeZone getTimeZone​(String id)
        Returns a TimeZone corresponding to the given id, or GMT for unknown ids.

        An ID can be an Olson name of the form Area/Location, such as America/Los_Angeles. The getAvailableIDs() method returns the supported names.

        This method can also create a custom TimeZone given an ID with the following syntax: GMT[+|-]hh[[:]mm]. For example, "GMT+05:00", "GMT+0500", "GMT+5:00", "GMT+500", "GMT+05", and "GMT+5" all return an object with a raw offset of +5 hours from UTC, and which does not use daylight savings. These are rarely useful, because they don't correspond to time zones actually in use by humans.

        Other than the special cases "UTC" and "GMT" (which are synonymous in this context, both corresponding to UTC), Android does not support the deprecated three-letter time zone IDs used in Java 1.1.

      • hasSameRules

        public boolean hasSameRules​(TimeZone timeZone)
        Returns true if timeZone has the same rules as this time zone.

        The base implementation returns true if both time zones have the same raw offset.

      • inDaylightTime

        public abstract boolean inDaylightTime​(Date time)
        Returns true if time is in a daylight savings time period for this time zone.
      • setDefault

        public static void setDefault​(TimeZone timeZone)
        Overrides the default time zone for the current process only.

        Warning: avoid using this method to use a custom time zone in your process. This value may be cleared or overwritten at any time, which can cause unexpected behavior. Instead, manually supply a custom time zone as needed.

        Parameters:
        timeZone - a custom time zone, or null to set the default to the user's preferred value.
      • setID

        public void setID​(String id)
        Sets the ID of this TimeZone.
      • setRawOffset

        public abstract void setRawOffset​(int offsetMillis)
        Sets the offset in milliseconds from UTC of this time zone's standard time.
      • useDaylightTime

        public abstract boolean useDaylightTime()
        Returns true if this time zone has a future transition to or from daylight savings time.

        Warning: this returns false for time zones like Asia/Kuala_Lumpur that have previously used DST but do not currently. A hypothetical country that has never observed daylight savings before but plans to start next year would return true.

        Warning: this returns true for time zones that use DST, even when it is not active.

        Use inDaylightTime(java.util.Date) to find out whether daylight savings is in effect at a specific time.

        Most applications should not use this method.