A <code>OLocale</code> object represents a specific geographical, political,
or cultural region. An operation that requires a <code>OLocale</code> to perform
its task is called <em>locale-sensitive</em> and uses the <code>OLocale</code>
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.
<P>
You create a <code>OLocale</code> object using one of the two constructors in
this class:
<blockquote>
<pre>
OLocale(String language, String country)
OLocale(String language, String country, String variant)
</pre>
</blockquote>
The first argument to both constructors is a valid <STRONG>ISO
Language Code.</STRONG> 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:
<BR><a href ="http://www.ics.uci.edu/pub/ietf/http/related/iso639.txt">
<code>http://www.ics.uci.edu/pub/ietf/http/related/iso639.txt</code></a>
<P>
The second argument to both constructors is a valid <STRONG>ISO Country
Code.</STRONG> 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:
<BR><a href="http://www.chemie.fu-berlin.de/diverse/doc/ISO_3166.html">
<code>http://www.chemie.fu-berlin.de/diverse/doc/ISO_3166.html</code></a>
<P>
The second constructor requires a third argument--the <STRONG>Variant.</STRONG>
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".
<P>
Because a <code>OLocale</code> object is just an identifier for a region,
no validity check is performed when you construct a <code>OLocale</code>.
If you want to see whether particular resources are available for the
<code>OLocale</code> you construct, you must query those resources. For
example, ask the <code>NumberFormat</code> for the locales it supports
using its <code>getAvailableLocales</code> method.
<BR><STRONG>Note:</STRONG> 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
<a href="java.util.ResourceBundle.html"><code>ResourceBundle</code></a>.
<P>
The <code>OLocale</code> class provides a number of convenient constants
that you can use to create <code>OLocale</code> objects for commonly used
locales. For example, the following creates a <code>OLocale</code> object
for the United States:
<blockquote>
<pre>
OLocale.US
</pre>
</blockquote>
<P>
Once you've created a <code>OLocale</code> you can query it for information about
itself. Use <code>getCountry</code> to get the ISO Country Code and
<code>getLanguage</code> to get the ISO Language Code. You can
use <code>getDisplayCountry</code> to get the
name of the country suitable for displaying to the user. Similarly,
you can use <code>getDisplayLanguage</code> to get the name of
the language suitable for displaying to the user. Interestingly,
the <code>getDisplayXXX</code> 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.
<P>
The JDK provides a number of classes that perform locale-sensitive
operations. For example, the <code>NumberFormat</code> class formats
numbers, currency, or percentages in a locale-sensitive manner. Classes
such as <code>NumberFormat</code> have a number of convenience methods
for creating a default object of that type. For example, the
<code>NumberFormat</code> class provides these three convenience methods
for creating a default <code>NumberFormat</code> object:
<blockquote>
<pre>
NumberFormat.getInstance()
NumberFormat.getCurrencyInstance()
NumberFormat.getPercentInstance()
</pre>
</blockquote>
These methods have two variants; one with an explicit locale
and one without; the latter using the default locale.
<blockquote>
<pre>
NumberFormat.getInstance(myLocale)
NumberFormat.getCurrencyInstance(myLocale)
NumberFormat.getPercentInstance(myLocale)
</pre>
</blockquote>
A <code>OLocale</code> is the mechanism for identifying the kind of object
(<code>NumberFormat</code>) that you would like to get. The locale is
<STRONG>just</STRONG> a mechanism for identifying objects,
<STRONG>not</STRONG> a container for the objects themselves.
<P>
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:
<blockquote>
<pre>
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.
</pre>
</blockquote>
