org.joda.time

Class DateTimeZone

java.lang.Object

org.joda.time.DateTimeZone

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

CachedDateTimeZone, FixedDateTimeZone

public abstract class DateTimeZone
extends Object
implements Serializable

DateTimeZone represents a time zone.

A time zone is a system of rules to convert time from one geographic location to another. For example, Paris, France is one hour ahead of London, England. Thus when it is 10:00 in London, it is 11:00 in Paris.

All time zone rules are expressed, for historical reasons, relative to Greenwich, London. Local time in Greenwich is referred to as Greenwich Mean Time (GMT). This is similar, but not precisely identical, to Universal Coordinated Time, or UTC. This library only uses the term UTC.

Using this system, America/Los_Angeles is expressed as UTC-08:00, or UTC-07:00 in the summer. The offset -08:00 indicates that America/Los_Angeles time is obtained from UTC by adding -08:00, that is, by subtracting 8 hours.

The offset differs in the summer because of daylight saving time, or DST. The following definitions are helpful:

• UTC - The reference time.
• Offset - The amount of time a zone differs from UTC. This can vary during the year.
• Daylight Saving - The process of having two offsets each year, one in winter and one in summer.
• Raw offset - The base offset of the zone.
• Additional offset - The additional offset on top of the raw offset. This is typically zero in winter and one hour in summer in zones that apply DST.
• Actual offset - The actual offset that applies, which is the combination of the raw offset and additional offset.

For example, in 2018 Greece applied daylight saving. Throughout the whole year, the raw offset was +02:00. In winter, the additional offset was zero, while in summer the additional offset was one hour. Thus, the actual offset was +02:00 in winter and +03:00 in summer.

Note: Some governments, most notably Ireland, define daylight saving by describing a "standard" time in summer and a negative DST offset in winter. Joda-Time, like the JDK, follows a model for time-zone data where there is a raw offset all year round and a positive additional offset. As such, callers cannot assume that the raw offset is that defined by law for the zone.

Note: Some governments define a daylight saving time that applies for two separate periods. For example, the year might be winter time, then summer time, then a special time equal to winter time, then back to summer time before finally dropping back to winter time. As such, callers cannot assume that the raw and DST offsets directly correlate to summer and winter.

Unlike the Java TimeZone class, DateTimeZone is immutable. It also only supports long format time zone ids. Thus PST and ECT are not accepted. However, the factory that accepts a TimeZone will attempt to convert from the old short id to a suitable long id.

There are four approaches to loading time-zone data, which are tried in this order:

1. load the specific Provider specified by the system property org.joda.time.DateTimeZone.Provider.
2. load ZoneInfoProvider using the data in the filing system folder pointed to by system property org.joda.time.DateTimeZone.Folder.
3. load ZoneInfoProvider using the data in the classpath location org/joda/time/tz/data.
4. load UTCProvider

Unless you override the standard behaviour, the default if the third approach.

DateTimeZone is thread-safe and immutable, and all subclasses must be as well.

Since:

1.0

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_TZ_DATA_PATH The default TZ data path This is the default classpath location containing the compiled data files.
static DateTimeZone	UTC The time zone for Universal Coordinated Time

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DateTimeZone(String id) Constructor.

Method Summary

Modifier and Type	Method and Description
long	adjustOffset(long instant, boolean earlierOrLater) Adjusts the offset to be the earlier or later one during an overlap.
long	convertLocalToUTC(long instantLocal, boolean strict) Converts a local instant to an actual UTC instant with the same local time.
long	convertLocalToUTC(long instantLocal, boolean strict, long originalInstantUTC) Converts a local instant to an actual UTC instant with the same local time attempting to use the same offset as the original.
long	convertUTCToLocal(long instantUTC) Converts an actual UTC instant to a local instant with the same local time.
abstract boolean	equals(Object object) Compare this datetime zone with another.
static DateTimeZone	forID(String id) Gets a time zone instance for the specified time zone id.
static DateTimeZone	forOffsetHours(int hoursOffset) Gets a time zone instance for the specified offset to UTC in hours.
static DateTimeZone	forOffsetHoursMinutes(int hoursOffset, int minutesOffset) Gets a time zone instance for the specified offset to UTC in hours and minutes.
static DateTimeZone	forOffsetMillis(int millisOffset) Gets a time zone instance for the specified offset to UTC in milliseconds.
static DateTimeZone	forTimeZone(TimeZone zone) Gets a time zone instance for a JDK TimeZone.
static Set<String>	getAvailableIDs() Gets all the available IDs supported.
static DateTimeZone	getDefault() Gets the default time zone.
String	getID() Gets the ID of this datetime zone.
long	getMillisKeepLocal(DateTimeZone newZone, long oldInstant) Gets the millisecond instant in another zone keeping the same local time.
String	getName(long instant) Gets the long name of this datetime zone suitable for display using the default locale.
String	getName(long instant, Locale locale) Gets the long name of this datetime zone suitable for display using the specified locale.
abstract String	getNameKey(long instant) Returns a non-localized name that is unique to this time zone.
static NameProvider	getNameProvider() Gets the name provider factory.
abstract int	getOffset(long instant) Gets the millisecond offset to add to UTC to get local time.
int	getOffset(ReadableInstant instant) Gets the millisecond offset to add to UTC to get local time.
int	getOffsetFromLocal(long instantLocal) Gets the millisecond offset to subtract from local time to get UTC time.
static Provider	getProvider() Gets the zone provider factory.
String	getShortName(long instant) Gets the short name of this datetime zone suitable for display using the default locale.
String	getShortName(long instant, Locale locale) Gets the short name of this datetime zone suitable for display using the specified locale.
abstract int	getStandardOffset(long instant) Gets the raw millisecond offset to add to UTC.
int	hashCode() Gets a hash code compatible with equals.
abstract boolean	isFixed() Returns true if this time zone has no transitions.
boolean	isLocalDateTimeGap(LocalDateTime localDateTime) Checks if the given LocalDateTime is within a gap.
boolean	isStandardOffset(long instant) Checks whether, at a particular instant, the offset is raw or not.
abstract long	nextTransition(long instant) Advances the given instant to where the time zone offset or name changes.
abstract long	previousTransition(long instant) Retreats the given instant to where the time zone offset or name changes.
static void	setDefault(DateTimeZone zone) Sets the default time zone.
static void	setNameProvider(NameProvider nameProvider) Sets the name provider factory.
static void	setProvider(Provider provider) Sets the zone provider factory.
String	toString() Gets the datetime zone as a string, which is simply its ID.
TimeZone	toTimeZone() Get the datetime zone as a TimeZone.
protected Object	writeReplace() By default, when DateTimeZones are serialized, only a "stub" object referring to the id is written out.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

UTC

public static final DateTimeZone UTC

The time zone for Universal Coordinated Time

DEFAULT_TZ_DATA_PATH

public static final String DEFAULT_TZ_DATA_PATH

The default TZ data path This is the default classpath location containing the compiled data files.

See Also:

Constant Field Values

Constructor Detail

DateTimeZone

protected DateTimeZone(String id)

Constructor.

Parameters:

id - the id to use

Throws:

IllegalArgumentException - if the id is null

Method Detail

getDefault

public static DateTimeZone getDefault()

Gets the default time zone.

The default time zone is derived from the system property org.joda.time.DateTimeZone.Timezone. If that is null or is not a valid identifier, then the value of the JDK TimeZone default is converted. If that fails, UTC is used.

NOTE: If the java.util.TimeZone default is updated after calling this method, then the change will not be picked up here.

NOTE: This previously checked the user.timezone property, see issue #587.

Returns:

the default datetime zone object

setDefault

public static void setDefault(DateTimeZone zone)
                       throws SecurityException

Sets the default time zone.

NOTE: Calling this method does not set the java.util.TimeZone default.

Parameters:

zone - the default datetime zone object, must not be null

Throws:

IllegalArgumentException - if the zone is null

SecurityException - if the application has insufficient security rights

forID

public static DateTimeZone forID(String id)

Gets a time zone instance for the specified time zone id.

The time zone id may be one of those returned by getAvailableIDs. Short ids, as accepted by TimeZone, are not accepted. All IDs must be specified in the long format unless detailed below.

A locale independent, fixed offset, datetime zone can be specified using the form [+-]hh:mm. The offset may be prefixed by 'UTC', 'GMT' or 'UT'. In addition, the IDs 'Z', 'UTC', 'GMT' and 'UT' will return a UTC equivalent time-zone.

Parameters:

id - the ID of the datetime zone, null means default

Returns:

the DateTimeZone object for the ID

Throws:

IllegalArgumentException - if the ID is not recognised

forOffsetHours

public static DateTimeZone forOffsetHours(int hoursOffset)
                                   throws IllegalArgumentException

Gets a time zone instance for the specified offset to UTC in hours. This method assumes standard length hours.

This factory is a convenient way of constructing zones with a fixed offset.

Parameters:

hoursOffset - the offset in hours from UTC, from -23 to +23

Returns:

the DateTimeZone object for the offset

Throws:

IllegalArgumentException - if the offset is too large or too small

forOffsetHoursMinutes

public static DateTimeZone forOffsetHoursMinutes(int hoursOffset,
                                                 int minutesOffset)
                                          throws IllegalArgumentException

Gets a time zone instance for the specified offset to UTC in hours and minutes. This method assumes 60 minutes in an hour, and standard length minutes.

This factory is a convenient way of constructing zones with a fixed offset. The hours value must be in the range -23 to +23. The minutes value must be in the range -59 to +59. The following combinations of sign for the hour and minute are possible:

  Hour    Minute    Example    Result
 
  +ve     +ve       (2, 15)    +02:15
  +ve     zero      (2, 0)     +02:00
  +ve     -ve       (2, -15)   IllegalArgumentException
 
  zero    +ve       (0, 15)    +00:15
  zero    zero      (0, 0)     +00:00
  zero    -ve       (0, -15)   -00:15
 
  -ve     +ve       (-2, 15)   -02:15
  -ve     zero      (-2, 0)    -02:00
  -ve     -ve       (-2, -15)  -02:15
 

Note that in versions before 2.3, the minutes had to be zero or positive.

Parameters:

hoursOffset - the offset in hours from UTC, from -23 to +23

minutesOffset - the offset in minutes from UTC, from -59 to +59

Returns:

the DateTimeZone object for the offset

Throws:

IllegalArgumentException - if any value is out of range, the minutes are negative when the hours are positive, or the resulting offset exceeds +/- 23:59:59.000

forOffsetMillis

public static DateTimeZone forOffsetMillis(int millisOffset)

Gets a time zone instance for the specified offset to UTC in milliseconds.

Parameters:

millisOffset - the offset in millis from UTC, from -23:59:59.999 to +23:59:59.999

Returns:

the DateTimeZone object for the offset

forTimeZone

public static DateTimeZone forTimeZone(TimeZone zone)

Gets a time zone instance for a JDK TimeZone.

DateTimeZone only accepts a subset of the IDs from TimeZone. The excluded IDs are the short three letter form (except UTC). This method will attempt to convert between time zones created using the short IDs and the full version.

This method is not designed to parse time zones with rules created by applications using SimpleTimeZone directly.

Parameters:

zone - the zone to convert, null means default

Returns:

the DateTimeZone object for the zone

Throws:

IllegalArgumentException - if the zone is not recognised

getAvailableIDs

public static Set<String> getAvailableIDs()

Gets all the available IDs supported.

Returns:

an unmodifiable Set of String IDs

getProvider

public static Provider getProvider()

Gets the zone provider factory.

The zone provider is a pluggable instance factory that supplies the actual instances of DateTimeZone.

Returns:

the provider

setProvider

public static void setProvider(Provider provider)
                        throws SecurityException

Sets the zone provider factory.

The zone provider is a pluggable instance factory that supplies the actual instances of DateTimeZone.

Parameters:

provider - provider to use, or null for default

Throws:

SecurityException - if you do not have the permission DateTimeZone.setProvider

IllegalArgumentException - if the provider is invalid

getNameProvider

public static NameProvider getNameProvider()

Gets the name provider factory.

The name provider is a pluggable instance factory that supplies the names of each DateTimeZone.

Returns:

the provider

setNameProvider

public static void setNameProvider(NameProvider nameProvider)
                            throws SecurityException

Sets the name provider factory.

The name provider is a pluggable instance factory that supplies the names of each DateTimeZone.

Parameters:

nameProvider - provider to use, or null for default

Throws:

SecurityException - if you do not have the permission DateTimeZone.setNameProvider

IllegalArgumentException - if the provider is invalid

getID

public final String getID()

Gets the ID of this datetime zone.

Returns:

the ID of this datetime zone

getNameKey

public abstract String getNameKey(long instant)

Returns a non-localized name that is unique to this time zone. It can be combined with id to form a unique key for fetching localized names.

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the name for

Returns:

name key or null if id should be used for names

getShortName

public final String getShortName(long instant)

Gets the short name of this datetime zone suitable for display using the default locale.

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

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the name for

Returns:

the human-readable short name in the default locale

getShortName

public String getShortName(long instant,
                           Locale locale)

Gets the short name of this datetime zone suitable for display using the specified locale.

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

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the name for

locale - the locale to get the name for

Returns:

the human-readable short name in the specified locale

getName

public final String getName(long instant)

Gets the long name of this datetime zone suitable for display using the default locale.

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

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the name for

Returns:

the human-readable long name in the default locale

getName

public String getName(long instant,
                      Locale locale)

Gets the long name of this datetime zone suitable for display using the specified locale.

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

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the name for

locale - the locale to get the name for

Returns:

the human-readable long name in the specified locale

getOffset

public abstract int getOffset(long instant)

Gets the millisecond offset to add to UTC to get local time.

This returns the actual offset from UTC for the zone at the specified instant. If the method is called with a different instant, the offset returned may be different as a result of daylight saving or other government rule changes.

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the offset for

Returns:

the millisecond offset to add to UTC to get local time

getOffset

public final int getOffset(ReadableInstant instant)

Gets the millisecond offset to add to UTC to get local time.

This returns the actual offset from UTC for the zone at the specified instant. If the method is called with a different instant, the offset returned may be different as a result of daylight saving or other government rule changes.

Parameters:

instant - instant to get the offset for, null means now

Returns:

the millisecond offset to add to UTC to get local time

getStandardOffset

public abstract int getStandardOffset(long instant)

Gets the raw millisecond offset to add to UTC.

This should be treated as an implementation detail. End-users should use getOffset(long).

This returns the raw offset from UTC for the zone at the specified instant, effectively ignoring DST. If the method is called with a different instant, the offset returned may be different as a result of government rule changes.

This method should be named getRawOffset() but cannot be renamed for compatibility reasons.

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the offset for

Returns:

the millisecond offset to add to UTC to get local time

isStandardOffset

public boolean isStandardOffset(long instant)

Checks whether, at a particular instant, the offset is raw or not.

This method can be used to estimate whether Summer Time (DST) applies at the specified instant. As a general rule, if the actual offset equals the raw offset at the specified instant then either winter time applies or the zone does not have DST rules. If the actual offset does not equal the raw offset, then some form of Summer Time applies.

The implementation of the method is simply whether getOffset(long) equals getStandardOffset(long) at the specified instant.

This method should be named isRawOffsetInUse() but cannot be renamed for compatibility reasons.

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z to get the offset for

Returns:

true if the offset at the given instant is the same as the raw offset

Since:

1.5

getOffsetFromLocal

public int getOffsetFromLocal(long instantLocal)

Gets the millisecond offset to subtract from local time to get UTC time. This offset can be used to undo adding the offset obtained by getOffset.

 millisLocal == millisUTC   + getOffset(millisUTC)
 millisUTC   == millisLocal - getOffsetFromLocal(millisLocal)
 

NOTE: After calculating millisLocal, some error may be introduced. At offset transitions (due to DST or other historical changes), ranges of local times may map to different UTC times.

For overlaps (where the local time is ambiguous), this method returns the offset applicable before the gap. The effect of this is that any instant calculated using the offset from an overlap will be in "summer" time.

For gaps, this method returns the offset applicable before the gap, ie "winter" offset. However, the effect of this is that any instant calculated using the offset from a gap will be after the gap, in "summer" time.

For example, consider a zone with a gap from 01:00 to 01:59:
Input: 00:00 (before gap) Output: Offset applicable before gap DateTime: 00:00
Input: 00:30 (before gap) Output: Offset applicable before gap DateTime: 00:30
Input: 01:00 (in gap) Output: Offset applicable before gap DateTime: 02:00
Input: 01:30 (in gap) Output: Offset applicable before gap DateTime: 02:30
Input: 02:00 (after gap) Output: Offset applicable after gap DateTime: 02:00
Input: 02:30 (after gap) Output: Offset applicable after gap DateTime: 02:30

NOTE: Prior to v2.0, the DST overlap behaviour was not defined and varied by hemisphere. Prior to v1.5, the DST gap behaviour was also not defined. In v2.4, the documentation was clarified again.

Parameters:

instantLocal - the millisecond instant, relative to this time zone, to get the offset for

Returns:

the millisecond offset to subtract from local time to get UTC time

convertUTCToLocal

public long convertUTCToLocal(long instantUTC)

Converts an actual UTC instant to a local instant with the same local time. This conversion is used before performing a calculation so that the calculation can be done using a simple local zone.

Parameters:

instantUTC - the UTC instant to convert to local

Returns:

the local instant with the same local time

Throws:

ArithmeticException - if the result overflows a long

Since:

1.5

convertLocalToUTC

public long convertLocalToUTC(long instantLocal,
                              boolean strict,
                              long originalInstantUTC)

Converts a local instant to an actual UTC instant with the same local time attempting to use the same offset as the original.

This conversion is used after performing a calculation where the calculation was done using a simple local zone. Whenever possible, the same offset as the original offset will be used. This is most significant during a daylight savings overlap.

Parameters:

instantLocal - the local instant to convert to UTC

strict - whether the conversion should reject non-existent local times

originalInstantUTC - the original instant that the calculation is based on

Returns:

the UTC instant with the same local time,

Throws:

ArithmeticException - if the result overflows a long

IllegalArgumentException - if the zone has no equivalent local time

Since:

2.0

convertLocalToUTC

public long convertLocalToUTC(long instantLocal,
                              boolean strict)

Converts a local instant to an actual UTC instant with the same local time. This conversion is used after performing a calculation where the calculation was done using a simple local zone.

Parameters:

instantLocal - the local instant to convert to UTC

strict - whether the conversion should reject non-existent local times

Returns:

the UTC instant with the same local time,

Throws:

ArithmeticException - if the result overflows a long

IllegalInstantException - if the zone has no equivalent local time

Since:

1.5

getMillisKeepLocal

public long getMillisKeepLocal(DateTimeZone newZone,
                               long oldInstant)

Gets the millisecond instant in another zone keeping the same local time.

The conversion is performed by converting the specified UTC millis to local millis in this zone, then converting back to UTC millis in the new zone.

Parameters:

newZone - the new zone, null means default

oldInstant - the UTC millisecond instant to convert

Returns:

the UTC millisecond instant with the same local time in the new zone

isLocalDateTimeGap

public boolean isLocalDateTimeGap(LocalDateTime localDateTime)

Checks if the given LocalDateTime is within a gap.

When switching into Daylight Savings Time there is typically a gap where a clock hour is missing. This method identifies whether the local datetime refers to such a gap.

Parameters:

localDateTime - the time to check, not null

Returns:

true if the given datetime refers to a gap

Since:

1.6

adjustOffset

public long adjustOffset(long instant,
                         boolean earlierOrLater)

Adjusts the offset to be the earlier or later one during an overlap.

Parameters:

instant - the instant to adjust

earlierOrLater - false for earlier, true for later

Returns:

the adjusted instant millis

isFixed

public abstract boolean isFixed()

Returns true if this time zone has no transitions.

Returns:

true if no transitions

nextTransition

public abstract long nextTransition(long instant)

Advances the given instant to where the time zone offset or name changes. If the instant returned is exactly the same as passed in, then no changes occur after the given instant.

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z

Returns:

milliseconds from 1970-01-01T00:00:00Z

previousTransition

public abstract long previousTransition(long instant)

Retreats the given instant to where the time zone offset or name changes. If the instant returned is exactly the same as passed in, then no changes occur before the given instant.

Parameters:

instant - milliseconds from 1970-01-01T00:00:00Z

Returns:

milliseconds from 1970-01-01T00:00:00Z

toTimeZone

public TimeZone toTimeZone()

Get the datetime zone as a TimeZone.

Returns:

the closest matching TimeZone object

equals

public abstract boolean equals(Object object)

Compare this datetime zone with another.

Overrides:

equals in class Object

Parameters:

object - the object to compare with

Returns:

true if equal, based on the ID and all internal rules

hashCode

public int hashCode()

Gets a hash code compatible with equals.

Overrides:

hashCode in class Object

Returns:

suitable hashcode

toString

public String toString()

Gets the datetime zone as a string, which is simply its ID.

Overrides:

toString in class Object

Returns:

the id of the zone

writeReplace

protected Object writeReplace()
                       throws ObjectStreamException

By default, when DateTimeZones are serialized, only a "stub" object referring to the id is written out. When the stub is read in, it replaces itself with a DateTimeZone object.

Returns:

a stub object to go in the stream

Throws:

ObjectStreamException - if the stream is invalid