29.12. Review Questions

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26.2. The Locale Class

A Locale object represents a geographical, political, or cultural region in which a specific language or custom is used. For example, Americans speak English, and the Chinese speak Chinese. The conventions for formatting dates, numbers , currencies, and percentages may differ from one country to another. The Chinese, for instance, use year/month/day to represent the date, while Americans use month/day/year. It is important to realize that locale is not defined only by country. For example, Canadians speak either Canadian English or Canadian French, depending on which region of Canada they reside in.

Note

Every Swing user -interface class has a locale property inherited from the Component class.

To create a Locale object, use one of the three constructors with a specified language and optional country and variant, as shown in Figure 26.1.

Figure 26.1. The Locale class encapsulates a locale.

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The language should be a valid language code, that is to say, one of the lowercase two-letter codes defined by ISO-639. For example, zh stands for Chinese, da for Danish, en for English, de for German, and ko for Korean. Table 26.1 lists the language codes.

Table 26.1. Common Language Codes

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Code	Language
da	Danish
de	German
el	Greek
en	English
es	Spanish
fi	Finnish
fr	French
it	Italian
ja	Japanese
ko	Korean
nl	Dutch
no	Norwegian
pt	Portuguese
sv	Swedish
tr	Turkish
zh	Chinese

The country should be a valid ISO country code, that is to say, one of the uppercase, two-letter codes defined by ISO-3166. For example, CA stands for Canada, CN for China, DK for Denmark, DE for Germany, and US for the United States. Table 26.2 lists the country codes.

Table 26.2. Common Country Codes

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Code	Country
AT	Austria
BE	Belgium
CA	Canada
CH	Switzerland
CN	China
DE	Germany
DK	Denmark
ES	Spain
FI	Finland
FR	France
GB	United Kingdom
GR	Greece
IE	Ireland
HK	Hong Kong
IT	Italy
JP	Japan
KR	Korea
NL	Netherlands
NO	Norway
PT	Portugal
SE	Sweden
TR	Turkey
TW	Taiwan
US	United States

The argument variant is rarely used and is needed only for exceptional or system-dependent situations to designate information specific to a browser or vendor. For example, the Norwegian language has two sets of spelling rules, a traditional one called bokm l and a new one called nynorsk . The locale for traditional spelling would be created as follows :

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   new   Locale(   "no"   ,   "NO"   ,   "B"   ); 

For convenience, the Locale class contains many predefined locale constants. Locale.CANADA is for the country Canada and language English; Locale.CANADA_FRENCH is for the country Canada and language French. Several other common constants are:

 Locale.US, Locale.UK, Locale.FRANCE, Locale.GERMANY, Locale.ITALY, Locale.CHINA, Locale.KOREA, Locale.JAPAN, and Locale.TAIWAN 

The Locale class also provided the following constants based on language:

 Locale.CHINESE, Locale.ENGLISH, Locale.FRENCH, Locale.GERMAN, Locale.ITALIAN, Locale.JAPANESE, Locale.KOREAN, Locale.SIMPLIFIED_CHINESE, and Locale.TRADITIONAL_CHINESE 

Tip

You can invoke the static method getAvailableLocales() in the Locale class to obtain all the available locales supported in the system. For example,

 Locale[] availableLocales = Calendar.getAvailableLocales(); 

returns all the locales in an array.

Tip

Your machine has a default locale. You may override it by supplying the language and region parameters when you run the program, as follows:

 java Duser.language=zh Duser.region=CN MainClass 

An operation that requires a Locale to perform its task is called locale-sensitive . Displaying a number as a date or time, for example, is a locale-sensitive operation; the number should be formatted according to the customs and conventions of the user's locale. The following sections introduce locale-sensitive operations.