Internationalization - Java Programming Language - Lecture Slides, Slides of Computer Science

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Chapter 12: Internationalization

• Processing Date and Time

– Locale

– Date

– TimeZone

– Calendar and GregorianCalendar

– DateFormat and

SimpleDateFormat

• Formatting Numbers

• Resource Bundles

Java’s International Support

1. Use Unicode (16-bit char)

 UTF-8 (8-bit for ASCII Char and 24-bit for other char)

2. Provide the Locale class to encapsulate information about a specific locale (such as date, time, and number).
3. Use the ResourceBundle class to separate locale-specific information such as status messages and the GUI component labels from the program.

Creating a Locale

To create a Locale object, you can use the following constructor in Locale class:

Locale(String language, String country)

Locale(String language, String country, String variant)

Language: iso639 Country code: iso

Example:

new Locale(“en”, “US”); or new Locale(“fr”, “CA”);

See Locale class for more methods: getDefault(), …

The Date Class

• The Date class represents a specific instant in time, with millisecond precision.
• You can construct a Date object using one of

the following two constructors in this class:

 public Date();

 public Date(long time);

Creating a TimeZone

• You can also get a TimeZone object by using the

class method getTimeZone(), along with a time

zone ID.

• For example, the time zone ID for central

standard time is CST. Therefore, you can get a

CST TimeZone object with the following:

TimeZone tz = TimeZone.getTimeZone("CST");

The Calendar Class

• A Date object represents a specific instant in time with millisecond precision.
• Calendar is an abstract base class for converting between a Date object and a set of integer fields, such as year, month, day , hour,

minute, and second.

• For example:

public final void set(int field, int value) public final void set(int year,int month, int date)

The get() Method

public final int get(int field)

This retrieves the value for a given time field.

The parameter field is a constant, such as

YEAR , MONTH , DAY , HOUR , MINUTE, SECOND ,

DAY_OF_WEEK , DAY_OF_MONTH ,

DAY_OF_YEAR , WEEK_OF_MONTH ,

WEEK_OF_YEAR , and so on.

GregorianCalendar Example

GregorianCalendar rightNow = new GregorianCalendar(); System.out.println("week of the year is "+rightNow.get(GregorianCalendar.WEEK_OF_YEAR));

This displays the week of the year for the current time.

DateFormat Formats

SHORT is completely numeric, such as

12.13.52 (for date) or 3:30pm (for time)

MEDIUM is longer, such as Jan 12, 1952

LONG is even longer, such as January 12, 1952

or 3:30:32pm

FULL is completely specified, such as

Tuesday, April 12, 1952 AD

or 3:30:42pm PST

Creating a DateFormat

You can use the getDateTimeInstance() method

to obtain a DateFormat object:

public static final DateFormat getDateTimeInstance (int dateStyle, int timeStyle, Locale aLocale)

This gets the date and time formatter with the given

formatting styles for the given locale.

Example 12.

Displaying a Clock

• Objective: Display current time based on the specified locale and time zone. The program can run as applet or application. The language, country, and time zone are passed to the program as command-line arguments like this:

javaw CurrentTimeApplet en US CST

CurrentTimeApplet

Run as Application Run as Applet

Example 12.

Displaying a Calendar

• Objective: Display the calendar based on

the specified locale. The user can

specify a locale from a combo box that

consists of a list of all the available

locales supported by the system.

CalendarApplet

Run as Application Run as Applet

The NumberFormat Class

• Use one of the factory class methods to

get a formatter.

1. Use getInstance() or getNumberInstance() to

get the normal number format.

2. Use getCurrencyInstance() to get the

currency number format.

3. Use getPercentInstance() to get a format

for displaying percentages. With this

format, a fraction like 0.53 is displayed

as 53%.

The NumberFormat Class

(cont.)

For example, to display a number in

percentages, you can use the following code

to create a formatter for the given locale.

NumberFormat percForm =

NumberFormat.getPercentInstance(locale);

You can then use percForm to format a

number into a string like this:

String s = percForm.format(0.075);