public
abstract
class
TimeZone
extends Object
implements
Serializable,
Cloneable
java.lang.Object | |
↳ | java.util.TimeZone |
Known Direct Subclasses |
TimeZone
represents a time zone offset, and also figures out 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
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:
You can use theTimeZone tz = TimeZone.getTimeZone("America/Los_Angeles");
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 a custom time zone ID can be specified to
produce a TimeZone. The syntax of a custom time zone ID is:
Hours must be between 0 to 23 and Minutes must be between 00 to 59. For example, "GMT+10" and "GMT+0010" mean ten hours and ten minutes ahead of GMT, respectively.CustomID:GMT
Sign Hours:
MinutesGMT
Sign Hours MinutesGMT
Sign Hours Sign: one of+ -
Hours: Digit Digit Digit Minutes: Digit Digit Digit: one of0 1 2 3 4 5 6 7 8 9
The format is locale independent and digits must be taken from the
Basic Latin block of the Unicode standard. No daylight saving time
transition schedule can be specified with a custom time zone ID. If
the specified string doesn't match the syntax, "GMT"
is used.
When creating a TimeZone
, the specified custom time
zone ID is normalized in the following syntax:
For example, TimeZone.getTimeZone("GMT-8").getID() returns "GMT-08:00".NormalizedCustomID:GMT
Sign TwoDigitHours:
Minutes Sign: one of+ -
TwoDigitHours: Digit Digit Minutes: Digit Digit Digit: one of0 1 2 3 4 5 6 7 8 9
See also:
Constants | |
---|---|
int |
LONG
A style specifier for |
int |
SHORT
A style specifier for |
Public constructors | |
---|---|
TimeZone()
Sole constructor. |
Public methods | |
---|---|
Object
|
clone()
Creates a copy of this |
static
String[]
|
getAvailableIDs()
Gets all the available IDs supported. |
static
String[]
|
getAvailableIDs(int rawOffset)
Gets the available IDs according to the given time zone offset in milliseconds. |
int
|
getDSTSavings()
Returns the amount of time to be added to local standard time to get local wall clock time. |
static
TimeZone
|
getDefault()
Gets the default |
String
|
getDisplayName(boolean daylightTime, int style, Locale locale)
Returns the |
final
String
|
getDisplayName(Locale locale)
Returns a long standard time name of this |
final
String
|
getDisplayName(boolean daylight, int style)
Returns a name in the specified |
final
String
|
getDisplayName()
Returns a long standard time name of this |
String
|
getID()
Gets the ID of this time zone. |
int
|
getOffset(long date)
Returns the offset of this time zone from UTC at the specified date. |
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. |
abstract
int
|
getRawOffset()
Returns the amount of time in milliseconds to add to UTC to get standard time in this time zone. |
static
TimeZone
|
getTimeZone(String id)
Gets the |
boolean
|
hasSameRules(TimeZone other)
Returns true if this zone has the same rule and offset as another zone. |
abstract
boolean
|
inDaylightTime(Date date)
Queries if the given |
boolean
|
observesDaylightTime()
Returns |
static
void
|
setDefault(TimeZone timeZone)
Sets the |
void
|
setID(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 |
Inherited methods | |
---|---|
From
class
java.lang.Object
|
int LONG
A style specifier for getDisplayName()
indicating
a long name, such as "Pacific Standard Time."
See also:
Constant Value: 1 (0x00000001)
int SHORT
A style specifier for getDisplayName()
indicating
a short name, such as "PST."
See also:
Constant Value: 0 (0x00000000)
TimeZone ()
Sole constructor. (For invocation by subclass constructors, typically implicit.)
Object clone ()
Creates a copy of this TimeZone
.
Returns | |
---|---|
Object |
a clone of this TimeZone
|
String[] getAvailableIDs ()
Gets all the available IDs supported.
Returns | |
---|---|
String[] |
an array of IDs. |
String[] getAvailableIDs (int rawOffset)
Gets the available IDs according to the given time zone offset in milliseconds.
Parameters | |
---|---|
rawOffset |
int :
the given time zone GMT offset in milliseconds. |
Returns | |
---|---|
String[] |
an array of IDs, where the time zone for that ID has the specified GMT offset. For example, "America/Phoenix" and "America/Denver" both have GMT-07:00, but differ in daylight saving behavior. |
See also:
int getDSTSavings ()
Returns the amount of time to be added to local standard time to get local wall clock time.
The default implementation returns 3600000 milliseconds
(i.e., one hour) if a call to useDaylightTime()
returns true
. Otherwise, 0 (zero) is returned.
If an underlying TimeZone
implementation subclass
supports historical and future Daylight Saving Time schedule
changes, this method returns the amount of saving time of the
last known Daylight Saving Time rule that can be a future
prediction.
If the amount of saving time at any given time stamp is
required, construct a Calendar
with this TimeZone
and the time stamp, and call Calendar.get
(
DST_OFFSET
)
.
Returns | |
---|---|
int |
the amount of saving time in milliseconds |
TimeZone getDefault ()
Gets the default TimeZone
for this host.
The source of the default TimeZone
may vary with implementation.
Returns | |
---|---|
TimeZone |
a default TimeZone . |
See also:
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 |
boolean :
true for daylight time, false for standard time. |
style |
int :
either LONG or SHORT . |
locale |
Locale :
the display locale.
|
Returns | |
---|---|
String |
String getDisplayName (Locale locale)
Returns a long standard time name of this TimeZone
suitable for
presentation to the user in the specified locale
.
This method is equivalent to:
getDisplayName(false,LONG
, locale)
Parameters | |
---|---|
locale |
Locale :
the locale in which to supply the display name. |
Returns | |
---|---|
String |
the human-readable name of this time zone in the given locale. |
Throws | |
---|---|
NullPointerException |
if locale is null . |
See also:
String getDisplayName (boolean daylight, int style)
Returns a name in the specified style
of this TimeZone
suitable for presentation to the user in the default locale. If the
specified daylight
is true
, a Daylight Saving Time name
is returned (even if this TimeZone
doesn't observe Daylight Saving
Time). Otherwise, a Standard Time name is returned.
This method is equivalent to:
getDisplayName(daylight, style, Locale.getDefault(DISPLAY
))
Parameters | |
---|---|
daylight |
boolean :
true specifying a Daylight Saving Time name, or
false specifying a Standard Time name |
style |
int :
either LONG or SHORT |
Returns | |
---|---|
String |
the human-readable name of this time zone in the default locale. |
Throws | |
---|---|
IllegalArgumentException |
if style is invalid. |
String getDisplayName ()
Returns a long standard time name of this TimeZone
suitable for
presentation to the user in the default locale.
This method is equivalent to:
getDisplayName(false,LONG
, Locale.getDefault(DISPLAY
))
Returns | |
---|---|
String |
the human-readable name of this time zone in the default locale. |
String getID ()
Gets the ID of this time zone.
Returns | |
---|---|
String |
the ID of this time zone. |
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.
This method returns a historically correct offset value if an underlying TimeZone implementation subclass supports historical Daylight Saving Time schedule and GMT offset changes.
Parameters | |
---|---|
date |
long :
the date represented in milliseconds since January 1, 1970 00:00:00 GMT |
Returns | |
---|---|
int |
the amount of time in milliseconds to add to UTC to get local time. |
See also:
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.
This method returns a historically correct offset if an
underlying TimeZone
implementation subclass
supports historical Daylight Saving Time schedule and GMT
offset changes.
Parameters | |
---|---|
era |
int :
the era of the given date. |
year |
int :
the year in the given date. |
month |
int :
the month in the given date.
Month is 0-based. e.g., 0 for January. |
day |
int :
the day-in-month of the given date. |
dayOfWeek |
int :
the day-of-week of the given date. |
milliseconds |
int :
the milliseconds in day in standard
local time. |
Returns | |
---|---|
int |
the offset in milliseconds to add to GMT to get local time. |
See also:
int getRawOffset ()
Returns the amount of time in milliseconds to add to UTC to get standard time in this time zone. Because this value is not affected by daylight saving time, it is called raw offset.
If an underlying TimeZone
implementation subclass
supports historical GMT offset changes, the method returns the
raw offset value of the current date. In Honolulu, for example,
its raw offset changed from GMT-10:30 to GMT-10:00 in 1947, and
this method always returns -36000000 milliseconds (i.e., -10
hours).
Returns | |
---|---|
int |
the amount of raw offset time in milliseconds to add to UTC. |
See also:
TimeZone getTimeZone (String id)
Gets the TimeZone
for the given ID.
Parameters | |
---|---|
id |
String :
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". Note that the support of abbreviations is
for JDK 1.1.x compatibility only and full names should be used. |
Returns | |
---|---|
TimeZone |
the specified TimeZone , or the GMT zone if the given ID
cannot be understood.
|
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 |
TimeZone :
the TimeZone object to be compared with |
Returns | |
---|---|
boolean |
true if the other zone is not null and is the same as this one, with the possible exception of the ID |
boolean inDaylightTime (Date date)
Queries if the given date
is in Daylight Saving Time in
this time zone.
Parameters | |
---|---|
date |
Date :
the given Date. |
Returns | |
---|---|
boolean |
true if the given date is in Daylight Saving Time,
false , otherwise.
|
boolean observesDaylightTime ()
Returns true
if this TimeZone
is currently in
Daylight Saving Time, or if a transition from Standard Time to
Daylight Saving Time occurs at any future time.
The default implementation returns true
if
useDaylightTime()
or inDaylightTime(new Date())
returns true
.
Returns | |
---|---|
boolean |
true if this TimeZone is currently in
Daylight Saving Time, or if a transition from Standard Time to
Daylight Saving Time occurs at any future time; false
otherwise. |
void setDefault (TimeZone timeZone)
Sets the TimeZone
that is
returned by the getDefault
method. If zone
is null, reset the default to the value it had originally when the
VM first started.
Parameters | |
---|---|
timeZone |
TimeZone :
the new default time zone |
See also:
void setID (String ID)
Sets the time zone ID. This does not change any other data in the time zone object.
Parameters | |
---|---|
ID |
String :
the new time zone ID.
|
void setRawOffset (int offsetMillis)
Sets the base time zone offset to GMT. This is the offset to add to UTC to get local time.
If an underlying TimeZone
implementation subclass
supports historical GMT offset changes, the specified GMT
offset is set as the latest GMT offset and the difference from
the known latest GMT offset value is used to adjust all
historical GMT offset values.
Parameters | |
---|---|
offsetMillis |
int :
the given base time zone offset to GMT.
|
boolean useDaylightTime ()
Queries if this TimeZone
uses Daylight Saving Time.
If an underlying TimeZone
implementation subclass
supports historical and future Daylight Saving Time schedule
changes, this method refers to the last known Daylight Saving Time
rule that can be a future prediction and may not be the same as
the current rule. Consider calling observesDaylightTime()
if the current rule should also be taken into account.
Returns | |
---|---|
boolean |
true if this TimeZone uses Daylight Saving Time,
false , otherwise. |
See also: