TimeZoneNames

public abstract class TimeZoneNames
extends Object implements Serializable

java.lang.Object
   ↳ android.icu.text.TimeZoneNames


TimeZoneNames is an abstract class representing the time zone display name data model defined by UTS#35 Unicode Locale Data Markup Language (LDML). The model defines meta zone, which is used for storing a set of display names. A meta zone can be shared by multiple time zones. Also a time zone may have multiple meta zone historic mappings.

For example, people in the United States refer the zone used by the east part of North America as "Eastern Time". The tz database contains multiple time zones "America/New_York", "America/Detroit", "America/Montreal" and some others that belong to "Eastern Time". However, assigning different display names to these time zones does not make much sense for most of people.

In CLDR (which uses LDML for representing locale data), the display name "Eastern Time" is stored as long generic display name of a meta zone identified by the ID "America_Eastern". Then, there is another table maintaining the historic mapping to meta zones for each time zone. The time zones in the above example ("America/New_York", "America/Detroit"...) are mapped to the meta zone "America_Eastern".

Sometimes, a time zone is mapped to a different time zone in the past. For example, "America/Indiana/Knox" had been moving "Eastern Time" and "Central Time" back and forth. Therefore, it is necessary that time zone to meta zones mapping data are stored by date range.

Note:

TimeZoneFormat assumes an instance of TimeZoneNames is immutable. If you want to provide your own TimeZoneNames implementation and use it with TimeZoneFormat, you must follow the contract.

The methods in this class assume that time zone IDs are already canonicalized. For example, you may not get proper result returned by a method with time zone ID "America/Indiana/Indianapolis", because it's not a canonical time zone ID (the canonical time zone ID for the time zone is "America/Indianapolis". See TimeZone.getCanonicalID(String) about ICU canonical time zone IDs.

In CLDR, most of time zone display names except location names are provided through meta zones. But a time zone may have a specific name that is not shared with other time zones. For example, time zone "Europe/London" has English long name for standard time "Greenwich Mean Time", which is also shared with other time zones. However, the long name for daylight saving time is "British Summer Time", which is only used for "Europe/London".

getTimeZoneDisplayName(String, NameType) is designed for accessing a name only used by a single time zone. But is not necessarily mean that a subclass implementation use the same model with CLDR. A subclass implementation may provide time zone names only through getTimeZoneDisplayName(String, NameType), or only through getMetaZoneDisplayName(String, NameType), or both.

The default TimeZoneNames implementation returned by getInstance(ULocale) uses the locale data imported from CLDR. In CLDR, set of meta zone IDs and mappings between zone IDs and meta zone IDs are shared by all locales. Therefore, the behavior of getAvailableMetaZoneIDs(), getAvailableMetaZoneIDs(String), getMetaZoneID(String, long), and getReferenceZoneID(String, String) won't be changed no matter what locale is used for getting an instance of TimeZoneNames.

Summary

Nested classes

enum TimeZoneNames.NameType

Time zone display name types  

Public methods

abstract Set<String> getAvailableMetaZoneIDs()

Returns an immutable set of all available meta zone IDs.

abstract Set<String> getAvailableMetaZoneIDs(String tzID)

Returns an immutable set of all available meta zone IDs used by the given time zone.

final String getDisplayName(String tzID, TimeZoneNames.NameType type, long date)

Returns the display name of the time zone at the given date.

String getExemplarLocationName(String tzID)

Returns the exemplar location name for the given time zone.

static TimeZoneNames getInstance(ULocale locale)

Returns an instance of TimeZoneNames for the specified locale.

static TimeZoneNames getInstance(Locale locale)

Returns an instance of TimeZoneNames for the specified Locale.

abstract String getMetaZoneDisplayName(String mzID, TimeZoneNames.NameType type)

Returns the display name of the meta zone.

abstract String getMetaZoneID(String tzID, long date)

Returns the meta zone ID for the given canonical time zone ID at the given date.

abstract String getReferenceZoneID(String mzID, String region)

Returns the reference zone ID for the given meta zone ID for the region.

static TimeZoneNames getTZDBInstance(ULocale locale)

Returns an instance of TimeZoneNames containing only short specific zone names (TimeZoneNames.NameType.SHORT_STANDARD and TimeZoneNames.NameType.SHORT_DAYLIGHT), compatible with the IANA tz database's zone abbreviations (not localized).

abstract String getTimeZoneDisplayName(String tzID, TimeZoneNames.NameType type)

Returns the display name of the time zone.

Inherited methods

Public methods

getAvailableMetaZoneIDs

added in API level 24
public abstract Set<String> getAvailableMetaZoneIDs ()

Returns an immutable set of all available meta zone IDs.

Returns
Set<String> An immutable set of all available meta zone IDs.

getAvailableMetaZoneIDs

added in API level 24
public abstract Set<String> getAvailableMetaZoneIDs (String tzID)

Returns an immutable set of all available meta zone IDs used by the given time zone.

Parameters
tzID String: The canonical time zone ID.

Returns
Set<String> An immutable set of all available meta zone IDs used by the given time zone.

getDisplayName

added in API level 24
public final String getDisplayName (String tzID, 
                TimeZoneNames.NameType type, 
                long date)

Returns the display name of the time zone at the given date.

Note: This method calls the subclass's getTimeZoneDisplayName(String, NameType) first. When the result is null, this method calls getMetaZoneID(String, long) to get the meta zone ID mapped from the time zone, then calls getMetaZoneDisplayName(String, NameType).

Parameters
tzID String: The canonical time zone ID.

type TimeZoneNames.NameType: The display name type. See TimeZoneNames.NameType.

date long: The date

Returns
String The display name for the time zone at the given date. When this object does not have a localized display name for the time zone with the specified type and date, null is returned.

getExemplarLocationName

added in API level 24
public String getExemplarLocationName (String tzID)

Returns the exemplar location name for the given time zone. When this object does not have a localized location name, the default implementation may still returns a programmatically generated name with the logic described below.

  1. Check if the ID contains "/". If not, return null.
  2. Check if the ID does not start with "Etc/" or "SystemV/". If it does, return null.
  3. Extract a substring after the last occurrence of "/".
  4. Replace "_" with " ".
For example, "New York" is returned for the time zone ID "America/New_York" when this object does not have the localized location name.

Parameters
tzID String: The canonical time zone ID

Returns
String The exemplar location name for the given time zone, or null when a localized location name is not available and the fallback logic described above cannot extract location from the ID.

getInstance

added in API level 24
public static TimeZoneNames getInstance (ULocale locale)

Returns an instance of TimeZoneNames for the specified locale.

Parameters
locale ULocale: The locale.

Returns
TimeZoneNames An instance of TimeZoneNames

getInstance

added in API level 24
public static TimeZoneNames getInstance (Locale locale)

Returns an instance of TimeZoneNames for the specified Locale.

Parameters
locale Locale: The Locale.

Returns
TimeZoneNames An instance of TimeZoneDisplayNames

getMetaZoneDisplayName

added in API level 24
public abstract String getMetaZoneDisplayName (String mzID, 
                TimeZoneNames.NameType type)

Returns the display name of the meta zone.

Parameters
mzID String: The meta zone ID.

type TimeZoneNames.NameType: The display name type. See TimeZoneNames.NameType.

Returns
String The display name of the meta zone. When this object does not have a localized display name for the given meta zone with the specified type or the implementation does not provide any display names associated with meta zones, null is returned.

getMetaZoneID

added in API level 24
public abstract String getMetaZoneID (String tzID, 
                long date)

Returns the meta zone ID for the given canonical time zone ID at the given date.

Parameters
tzID String: The canonical time zone ID.

date long: The date.

Returns
String The meta zone ID for the given time zone ID at the given date. If the time zone does not have a corresponding meta zone at the given date or the implementation does not support meta zones, null is returned.

getReferenceZoneID

added in API level 24
public abstract String getReferenceZoneID (String mzID, 
                String region)

Returns the reference zone ID for the given meta zone ID for the region. Note: Each meta zone must have a reference zone associated with a special region "001" (world). Some meta zones may have region specific reference zone IDs other than the special region "001". When a meta zone does not have any region specific reference zone IDs, this method return the reference zone ID for the special region "001" (world).

Parameters
mzID String: The meta zone ID.

region String: The region.

Returns
String The reference zone ID ("golden zone" in the LDML specification) for the given time zone ID for the region. If the meta zone is unknown or the implementation does not support meta zones, null is returned.

getTZDBInstance

added in API level 24
public static TimeZoneNames getTZDBInstance (ULocale locale)

Returns an instance of TimeZoneNames containing only short specific zone names (TimeZoneNames.NameType.SHORT_STANDARD and TimeZoneNames.NameType.SHORT_DAYLIGHT), compatible with the IANA tz database's zone abbreviations (not localized).
Note: The input locale is used for resolving ambiguous names (e.g. "IST" is parsed as Israel Standard Time for Israel, while it is parsed as India Standard Time for all other regions). The zone names returned by this instance are not localized.

Parameters
locale ULocale

Returns
TimeZoneNames

getTimeZoneDisplayName

added in API level 24
public abstract String getTimeZoneDisplayName (String tzID, 
                TimeZoneNames.NameType type)

Returns the display name of the time zone. Unlike getDisplayName(String, NameType, long), this method does not get a name from a meta zone used by the time zone.

Parameters
tzID String: The canonical time zone ID.

type TimeZoneNames.NameType: The display name type. See TimeZoneNames.NameType.

Returns
String The display name for the time zone. When this object does not have a localized display name for the given time zone with the specified type, null is returned.