Locale - java.util

Locale

The Locale class is instantiated to produce objects that describe a geographical or cultural region. It is one of several classes that provide you with the ability to write programs that can execute in different international environments. For example, the formats used to display dates, times, and numbers are different in various regions.

Internationalization is a large topic that is beyond the scope of this book. However, many programs will only need to deal with its basics, which include setting the current locale.

The Locale class defines the following constants that are useful for dealing with several common locales:

CANADA

CANADA_FRENCH

CHINA

CHINESE

ENGLISH

FRANCE

FRENCH

GERMAN

GERMANY

ITALIAN

ITALY

JAPAN

JAPANESE

KOREA

KOREAN

PRC

SIMPLIFIED_CHINESE

TAIWAN

TRADITIONAL_CHINESE

UK

US

For example, the expression Locale.CANADA represents the Locale object for Canada. The constructors for Locale are

Locale(String language) Locale(String language, String country)

Locale(String language, String country, String variant)

These constructors build a Locale object to represent a specific language and in the case of the last two, country. These values must contain standard language and country codes. Auxiliary variant information can be provided in variant.

Locale defines several methods. One of the most important is setDefault( ), shown here: static void setDefault(Locale localeObj)

This sets the default locale used by the JVM to that specified by localeObj. Some other interesting methods are the following:

final String getDisplayCountry( ) final String getDisplayLanguage( ) final String getDisplayName( )

These return human-readable strings that can be used to display the name of the country, the name of the language, and the complete description of the locale.

The default locale can be obtained using getDefault( ), shown here: static Locale getDefault( )

JDK 7 added significant upgrades to the Locale class that support Internet Engineering Task Force (IETF) BCP 47, which defines tags for identifying languages, and Unicode Technical Standard (UTS) 35, which defines the Locale Data Markup Language (LDML). Support for BCP 47 and UTS 35 caused several features to be added to Locale, including several new methods and the Locale.Builder class. Among others, new methods include getScript( ), which obtains the locale’s script, and toLanguageTag( ), which obtains a string that contains the locale’s language tag. The Locale.Builder class constructs Locale instances. It ensures that a locale specification is well-formed as defined by BCP 47. (The Locale constructors do not provide such a check.) Several new methods have also been added to Locale by JDK 8. Among these are methods that support filtering, extensions, and lookups.

Calendar and GregorianCalendar are examples of classes that operate in a locale-sensitive manner. DateFormat and SimpleDateFormat also depend on the locale.