This section illustrates the use of a
ListResourceBundle object
with an example program called ListDemo.
The text that follows explains each step involved in creating
the ListDemo program, along with the
ListResourceBundle subclasses
that support it.
The source code for the program is in
ListDemo.java.
1. Create the ListResourceBundle Subclasses
A ListResourceBundle is backed up by a class file.
Therefore, the first step is to create a class file
for every supported Locale.
In the ListDemo program, the base name
of the ListResourceBundle is StatsBundle.
Since ListDemo supports three different
Locale objects, it requires the following class files:
StatsBundle_en_CA.class
StatsBundle_fr_FR.class
StatsBundle_ja_JP.class
The StatsBundle class for Japan is defined in the source
code that follows.
Note that the class name is constructed by appending the
language and country codes to the base name of
the ListResourceBundle.
Inside the class,
the two-dimensional contents array is initialized with
the key-value pairs. The keys are the first element
in each pair: GDP, Population, and Literacy.
The keys must be String objects, and they
must be the same in every class in the StatsBundle set.
The values can be any type of object.
In this example, the values are two Integer objects and
a Double object.
import java.util.*;
public class StatsBundle_ja_JP extends ListResourceBundle {
public Object[][] getContents() {
return contents;
}
private Object[][] contents = {
{"GDP", new Integer(21300)},
{"Population", new Integer(125449703)},
{"Literacy", new Double(0.99)},
};
}
2. Specify the Locale
The ListDemo program defines the
Locale objects
as follows:
Locale[] supportedLocales = {
new Locale("en","CA"),
new Locale("ja","JP"),
new Locale("fr","FR")
};
Each Locale object corresponds to
one of the StatsBundle classes.
For example, the Japanese Locale, which was defined with the
ja and JP codes,
matches the StatsBundle_ja_JP.class.
3. Create the ResourceBundle
To create the ListResourceBundle,
invoke the getBundle
method. The following line of code specifies
the base name of the class (StatsBundle)
and the Locale:
ResourceBundle stats =
ResourceBundle.getBundle("StatsBundle",currentLocale);
The getBundle method searches for a class
whose name
begins with StatsBundle and is followed
by the language and country codes of the specified
Locale.
For example, if the currentLocale is
created with the ja and JP codes, then
getBundle returns a ListResourceBundle loaded
from class StatsBundle_ja_JP.
4. Fetch the Localized Objects
Now that the program has a ListResourceBundle
for the appropriate Locale, it can fetch
the localized objects by their keys.
The following line of code retrieves the
literacy rate by invoking getObject with the
"Literacy" key parameter.
Since getObject returns an object, cast it
to a Double:
Double lit = (Double)stats.getObject("Literacy");
5. Run the Demo Program
The ListDemo program prints
the data it fetched with the getBundle method:
Locale = en_CA
GDP = 24400
Population = 28802671
Literacy = 0.97
Locale = ja_JP
GDP = 21300
Population = 125449703
Literacy = 0.99
Locale = fr_FR
GDP = 20200
Population = 58317450
Literacy = 0.99
