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TimeZone Class Reference

TimeZone represents a time zone offset, and also figures out daylight savings. More...

#include <timezone.h>

Inheritance diagram for TimeZone:

SimpleTimeZone

Public Types

enum  EDisplayType { SHORT = 1, LONG }
 Enum for use with getDisplayName.

Public Member Functions

virtual ~TimeZone ()
 
virtual UBool operator== (const TimeZone &that) const
 Returns true if the two TimeZones are equal.
UBool operator!= (const TimeZone &that) const
 Returns true if the two TimeZones are NOT equal; that is, if operator==() returns false.
virtual int32_t getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis, UErrorCode &status) const =0
 Returns the TimeZone's adjusted GMT offset (i.e.
virtual int32_t getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t millis) const =0
virtual int32_t getOffset (uint8_t era, int32_t year, int32_t month, int32_t day, uint8_t dayOfWeek, int32_t milliseconds, int32_t monthLength, UErrorCode &status) const =0
 Gets the time zone offset, for current date, modified in case of daylight savings.
virtual void setRawOffset (int32_t offsetMillis)=0
 Sets the TimeZone's raw GMT offset (i.e.
virtual int32_t getRawOffset (void) const =0
 Returns the TimeZone's raw GMT offset (i.e.
UnicodeStringgetID (UnicodeString &ID) const
 Fills in "ID" with the TimeZone's ID.
void setID (const UnicodeString &ID)
 Sets the TimeZone's ID to the specified value.
UnicodeStringgetDisplayName (UnicodeString &result) const
 Returns a name of this time zone suitable for presentation to the user in the default locale.
UnicodeStringgetDisplayName (const Locale &locale, UnicodeString &result) const
 Returns a name of this time zone suitable for presentation to the user in the specified locale.
UnicodeStringgetDisplayName (UBool daylight, EDisplayType style, UnicodeString &result) const
 Returns a name of this time zone suitable for presentation to the user in the default locale.
UnicodeStringgetDisplayName (UBool daylight, EDisplayType style, const Locale &locale, UnicodeString &result) const
 Returns a name of this time zone suitable for presentation to the user in the specified locale.
virtual UBool useDaylightTime (void) const =0
 Queries if this time zone uses daylight savings time.
virtual UBool inDaylightTime (UDate date, UErrorCode &status) const =0
 Queries if the given date is in daylight savings time in this time zone.
virtual UBool hasSameRules (const TimeZone &other) const
 Returns true if this zone has the same rule and offset as another zone.
virtual TimeZoneclone (void) const =0
 Clones TimeZone objects polymorphically.
virtual UClassID getDynamicClassID (void) const =0
 Returns a unique class ID POLYMORPHICALLY.

Static Public Member Functions

static const TimeZonegetGMT (void)
 The GMT time zone has a raw offset of zero and does not use daylight savings time.
static TimeZonecreateTimeZone (const UnicodeString &ID)
 Creates a TimeZone for the given ID.
static const UnicodeString ** createAvailableIDs (int32_t rawOffset, int32_t &numIDs)
 Returns a list of time zone IDs, one for each time zone with a given GMT offset.
static const UnicodeString ** createAvailableIDs (const char *country, int32_t &numIDs)
 Returns a list of time zone IDs associated with the given country.
static const UnicodeString ** createAvailableIDs (int32_t &numIDs)
 Returns a list of all time zone IDs supported by the TimeZone class (i.e.
static int32_t countEquivalentIDs (const UnicodeString &id)
 Returns the number of IDs in the equivalency group that includes the given ID.
static const UnicodeString getEquivalentID (const UnicodeString &id, int32_t index)
 Returns an ID in the equivalency group that includes the given ID.
static TimeZonecreateDefault (void)
 Creates a new copy of the default TimeZone for this host.
static void adoptDefault (TimeZone *zone)
 Sets the default time zone (i.e.
static void setDefault (const TimeZone &zone)
 Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted; the caller remains responsible for deleting it.
static UClassID getStaticClassID (void)
 Return the class ID for this class.

Protected Member Functions

 TimeZone ()
 Default constructor.
 TimeZone (const UnicodeString &id)
 Construct a timezone with a given ID.
 TimeZone (const TimeZone &source)
 Copy constructor.
TimeZoneoperator= (const TimeZone &right)
 Default assignment operator.

Detailed Description

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

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

You can also get a TimeZone using createTimeZone along with a time zone ID. For instance, the time zone ID for the Pacific Standard Time zone is "PST". So, you can get a PST TimeZone object with: <blockquote>

 TimeZone *tz = TimeZone::createTimeZone("PST");
 
</blockquote> You can use getAvailableIDs method to iterate through all the supported time zone IDs. 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:

<blockquote>

 GMT[+|-]hh[[:]mm]
 
</blockquote>

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 does not include daylight savings time.

TimeZone is an abstract class representing a time zone. A TimeZone is needed for Calendar to produce local time for a particular time zone. A TimeZone comprises three basic pieces of information:

(Only the ID is actually implemented in TimeZone; subclasses of TimeZone may handle daylight savings time and GMT offset in different ways. Currently we only have one TimeZone subclass: SimpleTimeZone.)

The TimeZone class contains a static list containing a TimeZone object for every combination of GMT offset and daylight-savings time rules currently in use in the world, each with a unique ID. Each ID consists of a region (usually a continent or ocean) and a city in that region, separated by a slash, (for example, Pacific Standard Time is "America/Los_Angeles.") Because older versions of this class used three- or four-letter abbreviations instead, there is also a table that maps the older abbreviations to the newer ones (for example, "PST" maps to "America/LosAngeles"). Anywhere the API requires an ID, you can use either form.

To create a new TimeZone, you call the factory function TimeZone::createTimeZone() and pass it a time zone ID. You can use the createAvailableIDs() function to obtain a list of all the time zone IDs recognized by createTimeZone().

You can also use TimeZone::createDefault() to create a TimeZone. This function uses platform-specific APIs to produce a TimeZone for the time zone corresponding to the client's computer's physical location. For example, if you're in Japan (assuming your machine is set up correctly), TimeZone::createDefault() will return a TimeZone for Japanese Standard Time ("Asia/Tokyo").


Constructor & Destructor Documentation

TimeZone::TimeZone  )  [protected]
 

Default constructor.

ID is initialized to the empty string.

TimeZone::TimeZone const UnicodeString id  )  [protected]
 

Construct a timezone with a given ID.

TimeZone::TimeZone const TimeZone source  )  [protected]
 

Copy constructor.


Member Function Documentation

static void TimeZone::adoptDefault TimeZone zone  )  [static]
 

Sets the default time zone (i.e.

, what's returned by getDefault()) to be the specified time zone. If NULL is specified for the time zone, the default time zone is set to the default host time zone. This call adopts the TimeZone object passed in; the clent is no longer responsible for deleting it.

Parameters:
zone A pointer to the new TimeZone object to use as the default.

virtual TimeZone* TimeZone::clone void   )  const [pure virtual]
 

Clones TimeZone objects polymorphically.

Clients are responsible for deleting the TimeZone object cloned.

Returns:
A new copy of this TimeZone object.

Implemented in SimpleTimeZone.

static int32_t TimeZone::countEquivalentIDs const UnicodeString id  )  [static]
 

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. 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 ICU 1.7

static const UnicodeString** TimeZone::createAvailableIDs int32_t &  numIDs  )  [static]
 

Returns a list of all time zone IDs supported by the TimeZone class (i.e.

, all IDs that it's legal to pass to createTimeZone()). The caller owns the list that is returned, but does not own the strings contained in that list. Delete the array, but DON'T delete the elements in the array.

Parameters:
numIDs Receives the number of zone IDs returned.
Returns:
An array of UnicodeString pointers, where each is a time zone ID supported by the TimeZone class.

static const UnicodeString** TimeZone::createAvailableIDs const char *  country,
int32_t &  numIDs
[static]
 

Returns a list of time zone IDs associated with the given country.

Some zones are affiliated with no country (e.g., "UTC"); these may also be retrieved, as a group.

The caller owns the list that is returned, but does not own the strings contained in that list. Delete the array, but DON'T delete the elements in the array.

Parameters:
country The ISO 3166 two-letter country code, or NULL to retrieve zones not affiliated with any country.
numIDs Receives the number of items in the array that is returned.
Returns:
An array of UnicodeString pointers, where each UnicodeString is a time zone ID for a time zone with the given country. If there is no timezone that matches the country specified, NULL is returned.

static const UnicodeString** TimeZone::createAvailableIDs int32_t  rawOffset,
int32_t &  numIDs
[static]
 

Returns a list of time zone IDs, one for each time zone with a given GMT offset.

The return value is a list because there may be several times zones with the same GMT offset that differ in the way they handle daylight savings time. For example, the state of Arizona doesn't observe Daylight Savings time. So if you ask for the time zone IDs corresponding to GMT-7:00, you'll get back two time zone IDs: "America/Denver," which corresponds to Mountain Standard Time in the winter and Mountain Daylight Time in the summer, and "America/Phoenix", which corresponds to Mountain Standard Time year-round, even in the summer.

The caller owns the list that is returned, but does not own the strings contained in that list. Delete the array, but DON'T delete the elements in the array.

Parameters:
rawOffset An offset from GMT in milliseconds.
numIDs Receives the number of items in the array that is returned.
Returns:
An array of UnicodeString pointers, where each UnicodeString is a time zone ID for a time zone with the given GMT offset. If there is no timezone that matches the GMT offset specified, NULL is returned.

static TimeZone* TimeZone::createDefault void   )  [static]
 

Creates a new copy of the default TimeZone for this host.

Unless the default time zone has already been set using adoptDefault() or setDefault(), the default is determined by querying the system using methods in TPlatformUtilities. If the system routines fail, or if they specify a TimeZone or TimeZone offset which is not recognized, the TimeZone indicated by the ID kLastResortID is instantiated and made the default.

Returns:
A default TimeZone. Clients are responsible for deleting the time zone object returned.

static TimeZone* TimeZone::createTimeZone const UnicodeString ID  )  [static]
 

Creates a TimeZone for the given ID.

Parameters:
ID the ID for a TimeZone, either an abbreviation such as "PST", a full name such as "America/Los_Angeles", or a custom ID such as "GMT-8:00".
Returns:
the specified TimeZone, or the GMT zone if the given ID cannot be understood. Return result guaranteed to be non-null. If you require that the specific zone asked for be returned, check the ID of the return result.

UnicodeString& TimeZone::getDisplayName UBool  daylight,
EDisplayType  style,
const Locale &  locale,
UnicodeString result
const
 

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 format GMT[+-]hh:mm.

Parameters:
daylight if true, return the daylight savings name.
style either LONG or SHORT
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.

UnicodeString& TimeZone::getDisplayName UBool  daylight,
EDisplayType  style,
UnicodeString result
const
 

Returns a name of this time zone suitable for presentation to the user in the default locale.

If the display name is not available for the locale, then this method returns a string in the format GMT[+-]hh:mm.

Parameters:
daylight if true, return the daylight savings name.
style either LONG or SHORT
Returns:
the human-readable name of this time zone in the default locale.

UnicodeString& TimeZone::getDisplayName const Locale &  locale,
UnicodeString result
const
 

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, then this method returns a string in the format GMT[+-]hh:mm.

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.

UnicodeString& TimeZone::getDisplayName UnicodeString result  )  const
 

Returns a name of this time zone suitable for presentation to the user in the default locale.

This method returns the long name, not including daylight savings. If the display name is not available for the locale, then this method returns a string in the format GMT[+-]hh:mm.

Returns:
the human-readable name of this time zone in the default locale.

virtual UClassID TimeZone::getDynamicClassID void   )  const [pure virtual]
 

Returns a unique class ID POLYMORPHICALLY.

Pure virtual method. This method is to implement a simple version of RTTI, since not all C++ compilers support genuine RTTI. Polymorphic operator==() and clone() methods call this method.

Concrete subclasses of TimeZone must implement getDynamicClassID() and also a static method and data member:

 .     static UClassID getStaticClassID() { return (UClassID) }
 .     static char fgClassID;
 
Returns:
The class ID for this object. All objects of a given class have the same class ID. Objects of other classes have different class IDs.

Implemented in SimpleTimeZone.

static const UnicodeString TimeZone::getEquivalentID const UnicodeString id,
int32_t  index
[static]
 

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 ICU 1.7

static const TimeZone* TimeZone::getGMT void   )  [static]
 

The GMT time zone has a raw offset of zero and does not use daylight savings time.

This is a commonly used time zone.

UnicodeString & TimeZone::getID UnicodeString ID  )  const [inline]
 

Fills in "ID" with the TimeZone's ID.

Parameters:
ID Receives this TimeZone's ID.
Returns:
"ID"

virtual int32_t TimeZone::getOffset uint8_t  era,
int32_t  year,
int32_t  month,
int32_t  day,
uint8_t  dayOfWeek,
int32_t  milliseconds,
int32_t  monthLength,
UErrorCode status
const [pure virtual]
 

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.
monthLength the length of the given month in days.
Returns:
the offset to add *to* GMT to get local time.

Implemented in SimpleTimeZone.

virtual int32_t TimeZone::getOffset uint8_t  era,
int32_t  year,
int32_t  month,
int32_t  day,
uint8_t  dayOfWeek,
int32_t  millis
const [pure virtual]
 

Deprecated:
Remove after 2000-dec-31.
Use the other getOffset().

Implemented in SimpleTimeZone.

virtual int32_t TimeZone::getOffset uint8_t  era,
int32_t  year,
int32_t  month,
int32_t  day,
uint8_t  dayOfWeek,
int32_t  millis,
UErrorCode status
const [pure virtual]
 

Returns the TimeZone's adjusted GMT offset (i.e.

, the number of milliseconds to add to GMT to get local time in this time zone, taking daylight savings time into account) as of a particular reference date. The reference date is used to determine whether daylight savings time is in effect and needs to be figured into the offset that is returned (in other words, what is the adjusted GMT offset in this time zone at this particular date and time?). For the time zones produced by createTimeZone(), the reference data is specified according to the Gregorian calendar, and the date and time fields are in GMT, NOT local time.

Parameters:
era The reference date's era
year The reference date's year
month The reference date's month (0-based; 0 is January)
day The reference date's day-in-month (1-based)
dayOfWeek The reference date's day-of-week (1-based; 1 is Sunday)
millis The reference date's milliseconds in day, UTT (NOT local time).
Returns:
The offset in milliseconds to add to GMT to get local time.

Implemented in SimpleTimeZone.

virtual int32_t TimeZone::getRawOffset void   )  const [pure virtual]
 

Returns the TimeZone's raw GMT offset (i.e.

, the number of milliseconds to add to GMT to get local time, before taking daylight savings time into account).

Returns:
The TimeZone's raw GMT offset.

Implemented in SimpleTimeZone.

static UClassID TimeZone::getStaticClassID void   )  [inline, static]
 

Return the class ID for this class.

This is useful only for comparing to a return value from getDynamicClassID(). For example:

 .   Base* polymorphic_pointer = createPolymorphicObject();
 .   if (polymorphic_pointer->getDynamicClassID() ==
 .       Derived::getStaticClassID()) ...
 
Returns:
The class ID for all objects of this class.

Reimplemented in SimpleTimeZone.

virtual UBool TimeZone::hasSameRules const TimeZone other  )  const [virtual]
 

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.

Parameters:
other the TimeZone object to be compared with
Returns:
true if the given zone is the same as this one, with the possible exception of the ID

Reimplemented in SimpleTimeZone.

virtual UBool TimeZone::inDaylightTime UDate  date,
UErrorCode status
const [pure virtual]
 

Queries if the given date is in daylight savings time in this time zone.

Parameters:
date the given UDate.
Returns:
true if the given date is in daylight savings time, false, otherwise.
Deprecated:
Remove after 2000-dec-31.
Use useDaylightTime() instead.

Implemented in SimpleTimeZone.

UBool TimeZone::operator!= const TimeZone that  )  const [inline]
 

Returns true if the two TimeZones are NOT equal; that is, if operator==() returns false.

Parameters:
that The TimeZone object to be compared with.
Returns:
True if the given TimeZone is not equal to this TimeZone; false otherwise.

TimeZone& TimeZone::operator= const TimeZone right  )  [protected]
 

Default assignment operator.

virtual UBool TimeZone::operator== const TimeZone that  )  const [virtual]
 

Returns true if the two TimeZones are equal.

(The TimeZone version only compares IDs, but subclasses are expected to also compare the fields they add.)

Parameters:
that The TimeZone object to be compared with.
Returns:
True if the given TimeZone is equal to this TimeZone; false otherwise.

Reimplemented in SimpleTimeZone.

static void TimeZone::setDefault const TimeZone zone  )  [static]
 

Same as adoptDefault(), except that the TimeZone object passed in is NOT adopted; the caller remains responsible for deleting it.

Parameters:
zone The given timezone.

void TimeZone::setID const UnicodeString ID  )  [inline]
 

Sets the TimeZone's ID to the specified value.

This doesn't affect any other fields (for example, if you say< blockquote>

 .     TimeZone* foo = TimeZone::createTimeZone("America/New_York");
 .     foo.setID("America/Los_Angeles");
 
</blockquote> the time zone's GMT offset and daylight-savings rules don't change to those for Los Angeles. They're still those for New York. Only the ID has changed.)

Parameters:
ID The new timezone ID.

virtual void TimeZone::setRawOffset int32_t  offsetMillis  )  [pure virtual]
 

Sets the TimeZone's raw GMT offset (i.e.

, the number of milliseconds to add to GMT to get local time, before taking daylight savings time into account).

Parameters:
offsetMillis The new raw GMT offset for this time zone.

Implemented in SimpleTimeZone.

virtual UBool TimeZone::useDaylightTime void   )  const [pure virtual]
 

Queries if this time zone uses daylight savings time.

Returns:
true if this time zone uses daylight savings time, false, otherwise.

Implemented in SimpleTimeZone.


The documentation for this class was generated from the following file:
Generated on Sun May 22 20:18:37 2005 for ICU 2.1 by  doxygen 1.4.2