A OLocale
object represents a specific geographical, political, or cultural region.
An operation that requires a OLocale
to perform its task is called locale-sensitive and uses the OLocale
to tailor information for the user. For example, displaying a number is a locale-sensitive operation–the number should be formatted according to the customs/conventions of the user's native country, region, or culture.
You create a OLocale
object using one of the two constructors in this class:
OLocale(String language, String country)
OLocale(String language, String country, String variant)
The first argument to both constructors is a valid ISO Language Code. These codes are the lower-case two-letter codes as defined by ISO-639. You can find a full list of these codes at a number of sites, such as:
http://www.ics.uci.edu/pub/ietf/http/related/iso639.txt
The second argument to both constructors is a valid ISO Country Code. These codes are the upper-case two-letter codes as defined by ISO-3166. You can find a full list of these codes at a number of sites, such as:
http://www.chemie.fu-berlin.de/diverse/doc/ISO_3166.html
The second constructor requires a third argument–the Variant. The Variant codes are vendor and browser-specific. For example, use WIN for Windows, MAC for Macintosh, and POSIX for POSIX. Where there are two variants, separate them with an underscore, and put the most important one first. For example, a Traditional Spanish collation might be referenced, with "ES", "ES", "Traditional_WIN".
Because a OLocale
object is just an identifier for a region, no validity check is performed when you construct a OLocale
. If you want to see whether particular resources are available for the OLocale
you construct, you must query those resources. For example, ask the NumberFormat
for the locales it supports using its getAvailableLocales
method.
Note: When you ask for a resource for a particular locale, you get back the best available match, not necessarily precisely what you asked for. For more information, look at ResourceBundle
.
The OLocale
class provides a number of convenient constants that you can use to create OLocale
objects for commonly used locales. For example, the following creates a OLocale
object for the United States:
OLocale.US
Once you've created a OLocale
you can query it for information about itself. Use getCountry
to get the ISO Country Code and getLanguage
to get the ISO Language Code. You can use getDisplayCountry
to get the name of the country suitable for displaying to the user. Similarly, you can use getDisplayLanguage
to get the name of the language suitable for displaying to the user. Interestingly, the getDisplayXXX
methods are themselves locale-sensitive and have two versions: one that uses the default locale and one that uses the locale specified as an argument.
The JDK provides a number of classes that perform locale-sensitive operations. For example, the NumberFormat
class formats numbers, currency, or percentages in a locale-sensitive manner. Classes such as NumberFormat
have a number of convenience methods for creating a default object of that type. For example, the NumberFormat
class provides these three convenience methods for creating a default NumberFormat
object:
NumberFormat.getInstance()
NumberFormat.getCurrencyInstance()
NumberFormat.getPercentInstance()
These methods have two variants; one with an explicit locale and one without; the latter using the default locale.
NumberFormat.getInstance(myLocale)
NumberFormat.getCurrencyInstance(myLocale)
NumberFormat.getPercentInstance(myLocale)
A OLocale
is the mechanism for identifying the kind of object (NumberFormat
) that you would like to get. The locale is just a mechanism for identifying objects, not a container for the objects themselves.
Each class that performs locale-sensitive operations allows you to get all the available objects of that type. You can sift through these objects by language, country, or variant, and use the display names to present a menu to the user. For example, you can create a menu of all the collation objects suitable for a given language. Such classes must implement these three class methods:
public static OLocale[] getAvailableLocales()
public static String getDisplayName(OLocale objectLocale,
OLocale displayLocale)
public static final String getDisplayName(OLocale objectLocale)
getDisplayName will throw MissingResourceException if the locale
is not one of the available locales.