G11N/i18N/L10N

Internationalization is the process of designing an application so that it can be adapted to various languages and regions without engineering changes.

An internationalized program has the following characteristics:

• With the addition of localized data, the same executable can run worldwide.
• Textual elements, such as status messages and the GUI component labels, are not hardcoded in the program. Instead they are stored outside the source code and retrieved dynamically.
• Support for new languages does not require recompilation.
• Culturally-dependent data, such as dates and currencies, appear in formats that conform to the end user’s region and language.
• It can be localized quickly.

Java i18n Demo

import java.util.Locale;
import java.util.ResourceBundle;

public class Hello {

    public static void main(String[] args) {
        String language = "en";
        String country = "US";

        if (args.length == 1) {
            language = args[0];
        } else if (args.length == 2) {
            language = args[0];
            country = args[1];
        }

        var locale = new Locale(language, country);
        var messages = ResourceBundle.getBundle("messages", locale);

        System.out.print(messages.getString("hello") + " ");
        System.out.println(messages.getString("world"));
    }
}
import java.util.Locale;
import java.util.ResourceBundle;

public class Hello {

    public static void main(String[] args) {
        String language = "en";
        String country = "US";

        if (args.length == 1) {
            language = args[0];
        } else if (args.length == 2) {
            language = args[0];
            country = args[1];
        }

        var locale = new Locale(language, country);
        var messages = ResourceBundle.getBundle("messages", locale);

        System.out.print(messages.getString("hello") + " ");
        System.out.println(messages.getString("world"));
    }
}

messages_en.properties

hello=Hello(en)
world=World
hello=Hello(en)
world=World

messages_en_US.properties

world=World(en_US)
world=World(en_US)

messages_es.properties

hello=Hola
world=Mundo
hello=Hola
world=Mundo

execute java

java Hello.java
java Hello.java es
java Hello.java
java Hello.java es

Hello(en) World(en_US)
Hola Mundo
Hello(en) World(en_US)
Hola Mundo

Java i18N workflow

1. Create the Properties Files

greetings = Hello
farewell = Goodbye
inquiry = How are you?
greetings = Hello
farewell = Goodbye
inquiry = How are you?

2. Define the Locale

aLocale = new Locale("en","US");
aLocale = new Locale("en","US");

3. Create a ResourceBundle

messages = ResourceBundle.getBundle("MessagesBundle", currentLocale);
messages = ResourceBundle.getBundle("MessagesBundle", currentLocale);

MessagesBundle_en_US.properties
MessagesBundle_fr_FR.properties
MessagesBundle_de_DE.properties
MessagesBundle_en_US.properties
MessagesBundle_fr_FR.properties
MessagesBundle_de_DE.properties

4. Fetch the Text from the ResourceBundle

String msg1 = messages.getString("greetings");
String msg1 = messages.getString("greetings");

How does an internationalized program identify the appropriate language and region of its end users?

It references a Locale object.

Locale in i18N

Locale is the user-specific location and cultural information managed by a computer. (RFC6365)

A concept or identifier used by programmers to represent a particular collection of cultural, regional, or linguistic preferences.

Tags for Identifying Languages(BCP 47)

langtag = language["-" script]["-" region]*("-" variant)*("-" extension)["-" privateuse]
langtag = language["-" script]["-" region]*("-" variant)*("-" extension)["-" privateuse]

i18N IETF Standard

• Terminology Used in Internationalization in the IETF
• IETF BCP_{Best Current Practice} 47^{Language Tag Registry Update (LTRU)}
• Making Sense of Language Tags

Locale in Java

java.util.Locale

• Implements IETF BCP 47
  • RFC 4647: Matching of Language Tags
    • Filtering is used to get all matching locales
    • lookup is to choose the best matching locale
  • RFC 5646: Tags for Identifying Languages
• Refers to IETF RFC 2616
  • Quality Values
• Refers to ISO
  • ISO 639: Language codes
  • ISO 3166: Country codes
  • ISO 15924: Script code

How does Java get messages by locale identify?

It’s ResourceBundle!

ResourceBundle in Java

java.util.ResourceBundle

Others for i18N

• Common Language Data Repository(CLDR)^{Incorporated into JDK 8}
  • Locale-specific patterns for formatting and parsing: dates, times, timezones, numbers and currency values, measurement units,…
  • Translations of names: languages, scripts, countries and regions, currencies, eras, months, weekdays, day periods, time zones, cities, and time units, and sequences (and search keywords),…
  • Language & script information: characters used; plural cases; gender of lists; capitalization; rules for sorting & searching; writing direction; transliteration rules;…
  • Country information: language usage, currency information, calendar preference, week conventions,…
  • Validity: Definitions, aliases, and validity information for Unicode locales, languages, scripts, regions, and extensions,…
• UNICODE LOCALE DATA MARKUP LANGUAGE (LDML)

i18n Format

i18n Format Reference

1. https://docs.oracle.com/javase/tutorial/i18n/format/index.html
2. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl
3. http://rxaviers.github.io/javascript-globalization/
4. https://lokalise.com/blog/comparing-libraries-translating-js-apps/
5. https://github.com/unicode-org/cldr-json#package-organization

Outside of Java

• GUN gettext
  • C
  • C++
  • Python
  • PHP
  • Elixir
• ICU
  • Code Page Conversion
  • Collation
  • Formatting(CLDR)
  • Time Calculations
  • Unicode Support
  • Regular Expression
  • Bidi
  • Text Boundaries

Further reading list

• Building a minimal i18n library
• Clojure uses standard Java ResourceBundle
• awesome-i18n 1
• awesome-i18n 2
• A Beginner’s Guide to Internationalization in Java
• 国际化与本地化
• 国际化分析与处理
• ECMAScript® 2021 Internationalization API Specification
• iLib-js