The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
This section illustrates the use of a ListResourceBundle
object with a sample program called
. The text that follows explains each step involved in creating the ListDemo
ListDemo
program, along with the ListResourceBundle
subclasses that support it.
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 Locale
objects, it requires the following three 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) }, }; }
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 StatsBundle_ja_JP.class
.
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
. If the currentLocale
is created with the ja
and JP
codes, getBundle
returns a ListResourceBundle
corresponding to the class StatsBundle_ja_JP
, for example.
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");
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