Java Locale
last modified July 10, 2024
In this article we show how to localize Java programs.
Internationalization is the process of designing an application so that it can be adapted to various languages and regions. Localization is the process of customizing applications for a specific region or language.
Locale represents a specific geographical, political, or cultural
region.
Locale-sensitive data include:
- messages
- dates and times
- numbers
- currencies
- measurements
- phone numbers
- names
- postal addresses
Default locale
The default locale is determined with Locale.getDefault.
import java.util.Locale;
void main() {
var defLoc = Locale.getDefault();
System.out.println(defLoc.getDisplayCountry());
System.out.println(defLoc.getDisplayLanguage());
System.out.println(defLoc.getDisplayName());
System.out.println(defLoc.getISO3Country());
System.out.println(defLoc.getISO3Language());
System.out.println(defLoc.getLanguage());
System.out.println(defLoc.getCountry());
System.out.println("------------------------");
var skLoc = Locale.of("SK", "sk");
System.out.println(skLoc.getDisplayCountry());
System.out.println(skLoc.getDisplayLanguage());
System.out.println(skLoc.getDisplayName());
System.out.println(skLoc.getISO3Country());
System.out.println(skLoc.getISO3Language());
System.out.println(skLoc.getLanguage());
System.out.println(skLoc.getCountry());
}
The program prints the attributes of a default locale and a Slovak locale.
var defLoc = Locale.getDefault(); System.out.println(defLoc.getDisplayCountry()); System.out.println(defLoc.getDisplayLanguage()); System.out.println(defLoc.getDisplayName());
We get the default locale and print the display country name, language, and name.
$ java Main.java United States English English (United States) USA eng en US ------------------------ Slovakia Slovak Slovak (Slovakia) SVK slk sk SK
Locale constants
There are a few built-in locale constants such as Locale.US.
import java.text.NumberFormat;
import java.util.Locale;
void main() {
double n = 1240.35;
NumberFormat nf = NumberFormat.getInstance(Locale.US);
System.out.println(nf.format(n));
NumberFormat nf2 = NumberFormat.getInstance(Locale.FRANCE);
System.out.println(nf2.format(n));
NumberFormat nf3 = NumberFormat.getInstance(Locale.GERMAN);
System.out.println(nf3.format(n));
}
The program prints a number in Locale.US,
Locale.FRANCE, and Locale.GERMAN locales.
NumberFormat nf = NumberFormat.getInstance(Locale.US);
The NumberFormat.getInstance returns a general-purpose number
format for the specified locale.
System.out.println(nf.format(n));
We pass the value to the NumberFormat's format method.
$ java Main.java 1,240.35 1 240,35 1.240,35
Locale.Builder
Locales can be created with Locale.Builder.
import java.text.NumberFormat;
import java.util.Locale;
void main() {
double n = 1240.35;
var loc = new Locale.Builder()
.setLanguage("sk")
.setRegion("SK")
.build();
NumberFormat nf = NumberFormat.getInstance(loc);
System.out.println(nf.format(n));
var loc2 = new Locale.Builder()
.setLanguage("ja")
.setRegion("JP")
.build();
NumberFormat nf2 = NumberFormat.getInstance(loc2);
System.out.println(nf2.format(n));
}
The program localizes a value for Slovak and Japanese languages. The locales are created with a builder.
var loc = new Locale.Builder()
.setLanguage("sk")
.setRegion("SK")
.build();
A locale is built with the builder. We set the language with
setLanguage and the region with setRegion.
$ java Main.java 1 240,35 1,240.35
The Locale.of method
There are three methods for creating a Locale object.
Locale.of(String language) Locale.of(String language, String country) Locale.of(String language, String country, String variant)
We can specify language, country, and variants as parameters.
import java.math.BigDecimal;
import java.text.NumberFormat;
import java.util.Locale;
void main() {
var val = new BigDecimal("2530.45");
var skLoc = Locale.of("sk", "SK");
var huLoc = Locale.of("hu", "HU");
var ruLoc = Locale.of("ru", "RU");
NumberFormat cf1 = NumberFormat.getCurrencyInstance(skLoc);
System.out.println(cf1.format(val));
NumberFormat cf2 = NumberFormat.getCurrencyInstance(huLoc);
System.out.println(cf2.format(val));
NumberFormat cf3 = NumberFormat.getCurrencyInstance(ruLoc);
System.out.println(cf3.format(val));
}
In the example, we print a currency value in Slovak, Hungarian, and Russian locales.
var val = new BigDecimal("2530.45");
For currency values, we should use BigDecimal.
NumberFormat cf1 = NumberFormat.getCurrencyInstance(skLoc);
To format a currency value, we use the
NumberFormat.getCurrencyInstance to which we pass the locale.
$ java Main.java 2 530,45 € 2 530,45 Ft 2 530,45 ₽
Locale format datetime
With Locale and DateTimeFormatter, we can format
datetime values.
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.FormatStyle;
import java.util.Locale;
void main() {
var now = LocalDateTime.now();
var dtf1 = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM)
.withLocale(Locale.FRANCE);
System.out.println(now.format(dtf1));
var dtf2 = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM)
.withLocale(Locale.US);
System.out.println(now.format(dtf2));
var dtf3 = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM)
.withLocale(Locale.TRADITIONAL_CHINESE);
System.out.println(now.format(dtf3));
}
In the program, we format the current datetime in French, US, and Chinese locales.
var dtf1 = DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM)
.withLocale(Locale.FRANCE);
We choose a datetime format style with ofLocalizedDateTime and
set the locale with withLocale.
$ java Main.java 10 juil. 2024, 11:53:59 Jul 10, 2024, 11:53:59 AM 2024年7月10日 上午11:53:59
Locale ResourceBundle
A resource bundle is a Java properties file that contains locale-specific data. We localize messages with resource bundles.
w1=Earth w2=ocean
This is the default properties file; it is typically in English language. We have two words inside the file.
w1=Erde w2=ozean
The words_de.properties file contains words in German language.
w1=Земля w2=океан
The words_ru.properties file contains words in Russian language.
When using IntelliJ IDEA, we need to change the encoding of the properties file to utf-8; the default is ISO-8859-1.
import java.nio.charset.Charset;
import java.util.Locale;
import java.util.ResourceBundle;
void main() {
Locale[] locales = {
Locale.GERMAN,
Locale.of("ru", "RU"),
Locale.ENGLISH
};
System.out.println("w1:");
for (Locale locale : locales) {
getWord(locale, "w1");
}
System.out.println("w2:");
for (Locale locale : locales) {
getWord(locale, "w2");
}
}
void getWord(Locale curLoc, String key) {
ResourceBundle words = ResourceBundle.getBundle("main/resources/words", curLoc);
String value = words.getString(key);
System.out.printf("Locale: %s, Value: %s %n", curLoc, value);
}
In the code example, we print all the words used in three resource bundles.
ResourceBundle words = ResourceBundle.getBundle("main/resources/words", curLoc);
With the ResourceBundle.getBundle method, we get the bundle for the
currently used locale.
String value = words.getString(key);
From the bundle, we retrieve values with getString.
$ java Main.java w1: Locale: de, Value: Erde Locale: ru_RU, Value: Земля Locale: en, Value: Earth w2: Locale: de, Value: ozean Locale: ru_RU, Value: океан Locale: en, Value: ocean
Source
Java locale - language reference
In this article we have shown how to localize Java programs.
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