This section illustrates the use of a
ListResourceBundle object
with an example program called ListDemo.
We'll explain 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.
You may also find it helpful to examine the
output
produced by ListDemo.
1. Create the ListResourceBundle Subclasses
A ListResourceBundle is backed up by a class file.
Therefore, our 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_JA.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 Float object.
import java.util.*;
public class StatsBundle_ja_JA 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
In the ListDemo program, we define the
Locale objects
as follows:
Locale[] supportedLocales = {
new Locale("en","CA"),
new Locale("ja","JA"),
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 JA codes,
matches the StatsBundle_ja_JA.class.
3. Create the ResourceBundle
To create the ListResourceBundle,
we invoke the getBundle
method. In the following line of code, note
that we specify the base name of the class (StatsBundle)
and the Locale.
ResourceBundle stats =
ResourceBundle.getBundle("StatsBundle",currentLocale);
The getBundle method will 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 JA codes, then
getBundle returns a ListResourceBundle loaded
from class StatsBundle_ja_JA.
4. Fetch the Localized Objects
Now that we have a ListResourceBundle
for the appropriate Locale, we can fetch
the localized objects by their keys.
In the following line of code, we retrieve the
literacy rate by invoking getObject with the
"Literacy" key parameter.
Since getObject returns an object, we must cast it
to a Double:
Double lit = (Double)stats.getObject("Literacy");
