Internationalization

Advanced Java Programming
Topic: Internationalization
By
Ravi Kant Sahu
Asst. Professor, LPU

Contents
 Introduction
 Locale Class
 Displaying Date and Time
 Formatting Numbers
 Resource Bundles
Ravi Kant Sahu, Asst. Professor @ Lovely Professional University, Punjab (India)

Introduction
 Problem of customizing a program or page for different
countries or languages.
 It would be highly problematic to create and maintain
enough different versions to meet the needs of all clients
everywhere.

Internationalization
 Internationalization is the process of designing an
application so that it can be adapted to various languages
and regions without engineering changes.
 Java is the first language designed to support
Internationalization.

Characteristics
 An internationalized program has the following characteristics:
1. With the addition of localized data, the same executable can run
worldwide.
2. 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.
3. Support for new languages does not require recompilation.
4. Culturally-dependent data, such as dates and currencies, appear in
formats that conform to the end user's region and language.

Java Features to Support
Internationalization
1. Unicode
2. Locale Class
3. Resource Bundles
Note: Java characters use Unicode, a 16-bit encoding scheme
established by the Unicode Consortium to support the interchange,
processing, and display of written texts in the world’s diverse
languages.

LocaLe cLass

Locale
 A Locale object represents a geographical, political, or cultural
region in which a specific language or custom is used.
For example, Americans speak English, and the Chinese speak
Chinese.
 The conventions for formatting dates, numbers, and currencies
may differ from one country to another.
For example, The Chinese use year/month/day to represent the
date, while Americans use month/day/year.

Locale
 Locale class encapsulates information about a specific locale.
 A Locale object determines how locale-sensitive information,
such as date, time, and number, is displayed.
 The classes for formatting date, time, and numbers, and for
sorting strings are grouped in the java.text package.
 Every Swing class has a locale property inherited from the
Component class.

Creating Locale Object
 Constructor:
Locale (String Language)
Locale (String Language, String Country)
Locale (String Language, String Country, String Variant)

Language and Country Codes
Country Country Code Language Code
Spain ES es
Denmark DK da
Germany DE de
Greece GR el
China CN zh
Sweden SE sv
France FR fr
Norway NO no
Japan JP ja
United Kingdom GB en
Korea KR ko

Methods of Locale Class
String getCountry()
String getLanguage()
String getVariant()
Locale getDefault()
String getDisplayCountry()
String getDisplayLanguage()
String getDisplayName()
String getDisplayVariant()
Locale[] getAvailableLocales()

Locale Constants
 Predefined Country Constants
Locale.US, Locale.UK, Locale.FRANCE, Locale.GERMANY,
Locale.ITALY, Locale.CHINA, Locale.KOREA, Locale.JAPAN
 Predefined Language Constants
Locale.CHINESE, Locale.ENGLISH, Locale.FRENCH,
Locale.GERMAN, Locale.ITALIAN, Locale.JAPANESE,
Locale.KOREAN, Locale.SIMPLIFIED_CHINESE, and
Locale.TRADITIONAL_CHINESE

Displaying Time and Date

Displaying Date and Time
 Java provides a system independent encapsulation of date
and time in the java.util.Date class.
 It also provides java.util.TimeZone class for dealing with
time zones.
 java.util.Calendar can be used for extracting detailed
information from Date.

TimeZone Class
 TimeZone is an abstract class.
Constructor:
There is only default Constructor for TimeZone.

Methods of TimeZone Class
 static String[] getAvailableIDs()
used to find all the available time-zones supported in Java.
 static TimeZone getDefault()
used to obtain the default time-zone on host machine.
 static TimeZone getTimeZone(String ID)
used to get TimeZone object for specified TimeZoneID.
 String getID()
This method gets the ID of this time zone.

DateFormat Class
 An abstract class for date/time formatting subclasses which formats
and parses dates or time in a language-independent manner.
 Constructor:
protected DateFormat()
 Constants:
 SHORT is completely numeric, such as 01.12.52 or 3:30pm
 MEDIUM is longer, such as Jan 12, 1952
 LONG is even longer, such as January 12, 1952 or 3:30:32pm
 FULL is pretty completely specified, such as Tuesday, April 12, 1952
AD or 3:30:42pm IST.

Methods of DateFormat Class
 String format(Date date)
Formats a Date into a date/time string.
 static DateFormat getInstance()
Get a default date/time formatter that uses the SHORT style for both
the date and the time.
 void setTimeZone(TimeZone zone)
Sets the time zone for the calendar of this DateFormat object.

 static DateFormat getDateInstance()
Gets the date formatter with the default formatting style for the default
locale.
 static DateFormat getDateInstance(int style)
Gets the date formatter with the given formatting style for the default
locale.
 static DateFormat getDateInstance(int style, Locale aLocale)
Gets the date formatter with the given formatting style for the given
locale.

 static DateFormat getDateTimeInstance()
Gets the date/time formatter with the default formatting style for the
default locale.
 static DateFormat getDateTimeInstance(int dateStyle, int timeStyle)
 Gets the date/time formatter with the given date and time formatting styles
for the default locale.
 static DateFormat getDateTimeInstance(int dateStyle, int timeStyle,
Locale aLocale)
Gets the date/time formatter with the given formatting styles for the given
locale.

SimpleDateFormat Class
 Defined in java.text package.
 Enables to choose any user-defined pattern for date and time
formatting.
public SimpleDateFormat(String Pattern)
Example: SimpleDateFormat formatter = new
SimpleDateFormat("yyyy.MM.dd G 'at' hh:mm:ss z");
Note: G represents Era designator, and z is TimeZone.

DateFormatSymbols Class
 Constructors:
DateFormatSymbols()
DateFormatSymbols(Locale locale)
 Methods:
String[] getAmPmStrings()
String[] getEras()
String[] getMonths()

Methods
void setMonths(String[] newMonths)
String[] getShortMonths()
void setShortMonths(String[] newShortMonths)
String[] getWeekdays()
void setWeekdays(String[] newWeekdays)
String[] getShotWeekdays()
void setShortWeekdays(String[] newWeekdays)

Formatting numbers

Formatting Numbers
 Numbers are formatted using an abstract base class
java.text.NumberFormat .
 Formatting numbers is highly locale dependent.
Number: 5000.555
United States: 5,000.555
France: 5000,555
Germany: 5.000,555

Methods
 getInstance(): NumberFormat
 getInstance(locale: Locale): NumberFormat
 getIntegerInstance(): NumberFormat
 getIntegerInstance(locale: Locale): NumberFormat
 getCurrencyInstance(): NumberFormat
 getNumberInstance(): NumberFormat
 getNumberInstance(locale: Locale): NumberFormat
 getPercentInstance(): NumberFormat
 getPercentInstance(locale: Locale): NumberFormat

Methods
 format (number: double): String
 format (number: long): String
 getMaximumFractionDigits(): int
 setMaximumFractionDigits(newValue: int): void
 getMinimumFractionDigits(): int
 setMinimumFractionDigits(newValue: int): void
 getMaximumIntegerDigits(): int
 setMaximumIntegerDigits(newValue: int): void
 getMinimumIntegerDigits(): int
 setMinimumIntegerDigits(newValue: int): void
 parse(source: String): Number
 getAvailableLocales(): Locale[]

Formatting Numbers
 Plain Number Format:
NumberFormat nf = NumberFormat.getInstance(Locale l);
System.out.println(nf.format(1010.1055));
 Currency Format:
NumberFormat nf = NumberFormat.getCurrencyInstance(Locale l);
 Percent Format:
NumberFormat nf = NumberFormat.getPercentInstance(Locale l);

Parsing Numbers
 format(numericalValue) method is used to format a number into
a string.
 parse(String) method can be used to convert a formatted
plain number, currency value, or percent number with the
conventions of a certain locale into an instance of
java.lang.Number.
 The parse method throws a java.text.ParseException, if
parsing fails.

Example
U.S. $5,000.56 can be parsed into a number using the following
statements:
NumberFormat currencyFormat =
NumberFormat.getCurrencyInstance(Locale.US);
try {
Number number = currencyFormat.parse("$5,000.56");
System.out.println(number.doubleValue());
}
catch (java.text.ParseException ex) {
System.out.println("Parse failed");
}

DecimalFormat Class
 We can use the applyPattern(String pattern) method of the
DecimalFormat class to specify the patterns for displaying the
number.
 A pattern can specify the minimum number of digits before the
decimal point and the maximum number of digits after the
decimal point.
 The characters '0‘ and '#' are used to specify a required digit and
an optional digit, respectively.
 The optional digit is not displayed if it is zero.

Example
 The pattern "00.0##" indicates minimum two digits before the
decimal point and maximum three digits after the decimal point.
 If there are more actual digits before the decimal point, all of
them are displayed.
 If there are more than three digits after the decimal point, the
number of digits is rounded.
Example:
1987.16920 will be formatted as: 1987.169
1389.2387 will be formatted as: 1389.239

Resource Bundles

Resource Bundles
 A resource bundle is a Java class file or text file that provides
locale-specific information.
 This information can be accessed by Java programs dynamically.
 Resource bundles allows to write programs that separate the
locale-sensitive part of our code from the locale-independent
part.
 When a locale-specific resource is needed, our program can load
it from the resource bundle appropriate for the desired locale.

Resource Bundles
 The resources are placed inside the classes that extend the
ResourceBundle class or a subclass of ResourceBundle.
 Resource bundles contain key/value pairs.
 Each key uniquely identifies a locale-specific object in the bundle.
 Key is used to retrieve the object.
 ListResourceBundle is a subclass of ResourceBundle that is often
used to simplify the creation of resource bundles.

Example
public class MyResource extends java.util.ListResourceBundle
{
static final Object[][] contents = {
{"nationalFlag", "us.gif"},
{"nationalAnthem", "us.au"},
{"nationalColor", Color.red},
{"annualGrowthRate", new Double(7.8)}
};
public Object[][] getContents() {
return contents; }
}

Properties File
 If all the resources are strings, they can be placed in a convenient
text file with the extension .properties.

Resource Bundle Naming Conventions
1. BaseName_language_country_variant.class
2. BaseName_language_country.class
3. BaseName_language.class
4. BaseName.class
5. BaseName_language_country_variant.properties
6. BaseName_language_country.properties
7. BaseName_language.properties
8. BaseName.properties
 The getBundle method attempts to load the class that matches the
specified locale by language, country, and variant by searching the file
names in the order shown above.

Retrieving Values from Resource Bundle
 To retrieve values from a ResourceBundle in a program, we need
to create an instance of ResourceBundle using one of the following
two static methods:
public static final ResourceBundle getBundle(String
baseName) throws MissingResourceException
public static final ResourceBundle getBundle (String
baseName, Locale locale) throws MissingResourceException
 The first method returns a ResourceBundle for the default locale,
and second returns a ResourceBundle for the specified locale.

 getObject() method can be used to retrieve the value according to
the key.
ResourceBundle res = ResourceBundle.getBundle("MyResource");
String flagFile = (String)res.getObject("nationalFlag");
 If the resource value is a string, then getString() method is more
convenient to use.
String flagFile = res.getString("nationalFlag");

Character Encoding

Character Encoding
 Java programs use Unicode. When we read a character using text
I/O, the Unicode code of the character is returned.
 The encoding of the character in the file may be different.
 Java automatically converts it to the Unicode.
 When we write a character using text I/O, Java automatically
converts the Unicode of the character to the encoding specified for
the file.

Character Encoding
 We can specify an encoding scheme using a constructor of
Scanner/PrintWriter for text I/O, as follows:
public Scanner(File file, String encodingName)
public PrintWriter(File file, String encodingName)
Encoding Names:
https://docs.oracle.com/javase/1.5.0/docs/guide/intl/encoding.doc.
html

All the Best
for
Mid-Term exams

Internationalization

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