International Components for Unicode for Java (ICU4J)

Read Me for ICU4J 3.2

Release Date
Nov 22, 2004

For the most recent release, see the ICU4J download site.

Contents

Introduction to ICU4J

The International Components for Unicode (ICU) library provides robust and full-featured Unicode services on a wide variety of platforms. ICU supports the most current version of the Unicode standard, including support for supplementary characters (needed for GB 18030 repertoire support).

Java provides a strong foundation for global programs, and IBM and the ICU team played a key role in providing globalization technology to Java. But because of its long release schedule, Java cannot always keep up with evolving standards. The ICU team continues to extend Java's Unicode and internationalization support, focusing on improving performance, keeping current with the Unicode standard, and providing richer APIs, while remaining as compatible as possible with the original Java text and internationalization API design.

ICU4J is an add-on to the regular JVM that provides:

Note: We continue to provide assistance to Sun, and in some cases, ICU4J support has been rolled into a later release of Java. For example, the Thai word-break is now in Java 1.4. However, the most current and complete version is always found in ICU4J.

What Is New In This Release?

A complete report of the API changes between version 3.2 and version 3.0 of ICU4J can be found here. This report is generated by a tool and has some limitations, the most notable of which is that it does not properly reflect the effect of class inheritance changes. Also of course, being generated by a tool, the report does not provide explanation or commentary on the changes. For background information and clarification of changes it's always recommended that you check the mailing list and archives.

ULocale (RFC 3066) implementation complete

RFC 3066 defines a new format for Locale identifiers that incorporates information about the script as well as the language and region into the locale identifier. ICU4J has enhanced the ULocale class to provide this information. All ICU4J APIs that work with Locale have been overloaded to also work with ULocale. ULocale is now the preferred API for specifying a locale ID to ICU4J APIs.

RBNF, Transliterator data now in separate resource trees

More resource data has been moved out of the core resources into separate resource trees.  This will make it easier for clients to trim the data used by ICU4J.

License Information

The ICU projects (ICU4C and ICU4J) use the X license.  The X license is a non-viral and recommended free software license that is compatible with the GNU GPL license.  This became effective with release 1.8.1 of ICU4C and release 1.3.1 of ICU4J in mid-2001. All new ICU releases will adopt the X license; previous ICU releases continue to utilize the IPL (IBM Public License).  Users of previous releases of ICU who want to adopt new ICU releases will need to accept the terms and conditions of the X license.

The main effect of the change is to provide GPL compatibility.  The X license is listed as GPL compatible, see the GNU page at http://www.gnu.org/philosophy/license-list.html#GPLCompatibleLicenses. This means that GPL projects can now use ICU code, it does not mean that projects using ICU become subject to GPL.

The text of the X license is available at http://www.x.org/terms.htm. The IBM version contains the essential text of the license, omitting the X-specific trademarks and copyright notices. The full copy of ICU's license is included in the download package.

For more details please see the press announcement and the Project FAQ.

Platform Dependencies

Parts of ICU4J depend on functionality that is only available in JDK 1.4 or later, although some components work under earlier JVMs. All components should be compiled using a Java2 compiler, as even components that run under earlier JVMs can require language features that are only present in Java2. Currently 1.1.x, 1.2.x and 1.3.x JVMs are unsupported and untested, and you use the components on these JVMs at your own risk.

The reference platforms which we support and test ICU4J on are:

Please use the most recent updates of the supported JDK versions.

Additionally, we have built and tested ICU4J on the following unsupported platforms:

How to Download ICU4J

There are two ways to download the ICU4J releases.

For more details on how to download ICU4J directly from the web site, please also see http://oss.software.ibm.com/icu4j/download/index.html

The Structure and Contents of ICU4J

Below, $Root is the placement of the icu directory in your file system, like "drive:\...\icu4j" in your environment. "drive:\..." stands for any drive and any directory on that drive that you chose to install icu4j into.

Information and build files:

readme.html
(this file)		 A description of ICU4J (International Components for Unicode for Java)
license.html The X license, used by ICU4J
build.xml Ant build file. See How to Install and Build for more information

The source directories mirror the package structure of the code.
Core packages become part of the ICU4J jar file.
API packages contain classes with supported API.
RichText classes are Core and API, but can be removed from icu4j.jar, and can be built into their own jar.

$Root/src/com/ibm/icu/dev
Non-Core, Non-API		 Packages used for internal development:
  • Data: data used by tests and in building ICU
  • Demos: Calendar, Holiday, Break Iterator, Rule-based Number Format, Transformations
    (See below for more information about the demos.)
  • Tests: API and coverage tests of all functionality.
    For information about running the tests, see $Root/src/com/ibm/icu/dev/test/TestAll.java.
  • Tools: tools used to build data tables, etc.
$Root/src/com/ibm/icu/impl
Core, Non-API		 These are utility classes used from different ICU4J core packages.
$Root/src/com/ibm/icu/lang
Core, API		 Character properties package.
$Root/src/com/ibm/icu/math
Core, API		 Additional math classes.
$Root/src/com/ibm/icu/text
Core, API		 Additional text classes. These add to, and in some cases replace, related core Java classes:
  • Arabic shaping
  • Break iteration
  • Date formatting
  • Number formatting
  • Transliteration
  • Normalization
  • String manipulation
  • Collation
  • String search
  • Unicode compression
  • Unicode sets
$Root/src/com/ibm/icu/util
Core, API		 Additional utility classes:
  • Calendars - Gregorian, Buddhist, Hebrew, Islamic, Japanese
  • Holiday
  • TimeZone
  • VersionInfo
  • Iteration
$Root/src/com/ibm/richtext
RichText		 Styled text editing package. This includes demos, tests, and GUIs for editing and displaying styled text. The richtext package provides a scrollable display, typing, arrow-key support, tabs, alignment and justification, word- and sentence-selection (by double-clicking and triple-clicking, respectively), text styles, clipboard operations (cut, copy and paste) and a log of changes for undo-redo. Richtext uses Java's TextLayout and complex text support (provided to Sun by the ICU4J team).

Building ICU4J creates and populates the following directories:

$Root/classes contains all class files
$Root/doc contains JavaDoc for all packages

ICU4J data is stored in the following locations:

com.ibm.icu.impl.data Holds data used by the ICU4J core packages (com.ibm.icu.lang, com.ibm.icu.text, com.ibm.icu.util, com.ibm.icu.math and com.ibm.icu.text). In particular, all resource information is stored here.
com.ibm.icu.dev.data Holds data that is not part of ICU4J core, but rather part of a test, sample, or demo.

Where to get Documentation

The ICU user's guide contains lots of general information about ICU, in its C, C++, and Java incarnations.

The complete API documentation for ICU4J (javadoc) is available on the ICU4J web site, and can be built from the sources:

How to Install and Build

To install ICU4J, simply place the prebuilt jar file icu4j.jar on your Java CLASSPATH.  No other files are needed.

Eclipse users: See the ICU4J site for information on how to configure Eclipse to build ICU4J.

To build ICU4J, you will need a Java2 JDK and the Ant build system. We strongly recommend using the Ant build system to build ICU4J. It's recommended to install both the JDK and Ant somewhere outside the ICU4J directory. For example, on Linux you might install these in /usr/local.

Once the JDK and Ant are installed, building is just a matter of typing ant in the ICU4J root directory. This causes the Ant build system to perform a build as specified by the file build.xml, located in the ICU4J root directory. You can give Ant options like -verbose, and you can specify targets. Ant will only build what's been changed and will resolve dependencies properly. For example:

F:\icu4j>ant tests
Buildfile: build.xml
Project base dir set to: F:\icu4j
Executing Target: core
Compiling 71 source files to F:\icu4j\classes
Executing Target: tests
Compiling 24 source files to F:\icu4j\classes
Completed in 19 seconds

The following are some targets that you can provide to ant. For more targets run ant -projecthelp or see the build.xml file.

all Build all targets.
core Build the main class files in the subdirectory classes. If no target is specified, core is assumed.
tests Build the test class files.
demos Build the demos.
tools Build the tools.
docs Run javadoc over the main class files, generating an HTML documentation tree in the subdirectory doc.
jar Create a jar archive icu4j.jar in the root ICU4J directory containing the main class files.
jarSrc Like the jar target, but containing only the source files.
jarDocs Like the jar target, but containing only the docs.
richedit Build the richedit core class files and tests.
richeditJar Create the richedit jar file (which contains only the richedit core class files). The file richedit.jar will be created in the ./richedit subdirectory. Any existing file of that name will be overwritten.
richeditZip Create a zip archive of the richedit docs and jar file for distribution. The zip file richedit.zip will be created in the ./richedit subdirectory. Any existing file of that name will be overwritten.
clean Remove all built targets, leaving the source.

For more information, read the Ant documentation and the build.xml file.

After doing a build it is a good idea to run all the icu4j tests by typing
"ant check" or "java -classpath $Root/classes com.ibm.icu.dev.test.TestAll -nothrow".

(If you are allergic to build systems, as an alternative to using Ant you can build by running javac and javadoc directly. This is not recommended. You may have to manually create destination directories.)

How to modularize ICU4J

Some clients may not wish to ship all of ICU4J with their application, since the application might only use a small part of ICU4J. ICU4J release 2.6 and later provide build options to build individual ICU4J 'modules' for a more compact distribution. The modules are based on a service and the APIs that define it, e.g., the normalizer module supports all the APIs of the Normalizer class (and some others). Tests can be run to verify that the APIs supported by the module function correctly. Because of internal code dependencies, a module contains extra classes that are not part of the module's core service API. Some or most of the APIs of these extra classes will not work. Only the module's core service API is guaranteed. Other APIs may work partially or not at all, so client code should avoid them.

Individual modules are not built directly into their own separate jar files. Since their dependencies often overlap, using separate modules to 'add on' ICU4J functionality would result in unwanted duplication of class files. Instead, building a module causes a subset of ICU4J's classes to be built and put into ICU4J's standard build directory. After one or more module targets are built, the 'moduleJar' target can then be built, which packages the class files into a 'module jar.' Other than the fact that it contains fewer class files, little distinguishes this jar file from a full ICU4J jar file, and in fact they share the same name.

Currently ICU4J can be divided into the following modules:

Key:
Module Name Ant Targets Test Package Supported Size‡
Package* Main Classes†
* com.ibm. should be prepended to the package names listed.
† A bold class name core service APIs. Only APIs in these classes are fully supported.
‡ Sizes are of the compressed jar file containing only this module. Full size is 3,047 K.

Modules:
Normalizer normalizer, normalizerTests com.ibm.icu.dev.test.normalizer 444 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript
icu.text: Normalizer, Replaceable, ReplaceableString, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: ValueIterator, VersionInfo
Collator collator, collatorTests com.ibm.icu.dev.test.collator 1,507 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, lang.UProperty, UScript
icu.text: BreakDictionary, BreakIterator, BreakIteratorFactory, CanonicalIterator, CollationElementIterator, CollationKey, CollationParsedRuleBuilder, CollationRuleParser, Collator, CollatorReader, DictionaryBasedBreakIterator, Normalizer, Replaceable, ReplaceableString, RuleBasedBreakIterator, RuleBasedCollator, SearchIterator, StringSearch, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: ValueIterator, VersionInfo
Calendar calendar, calendarTests com.ibm.icu.dev.test.calendar 1,704 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript
icu.math: BigDecimal
icu.text: BreakIterator, ChineseDateFormat, ChineseDateFormatSymbols, DateFormat, DateFormatSymbols, DecimalFormat, DecimalFormatSymbols, Normalizer, NumberFormat, Replaceable, ReplaceableString, SimpleDateFormat, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: BuddhistCalendar, Calendar, CalendarAstronomer, CalendarCache, CalendarFactory, ChineseCalendar, Currency, DateRule, EasterHoliday, EasterRule, GregorianCalendar, HebrewCalendar, HebrewHoliday, Holiday, IslamicCalendar, JapaneseCalendar, RangeDateRule, SimpleDateRule, SimpleHoliday, SimpleTimeZone, SimpleTimeZoneAdapter, TimeZone, TimeZoneData, ValueIterator, VersionInfo
BreakIterator breakIterator, breakIteratorTests com.ibm.icu.dev.test.breakiterator 1,661 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript
icu.text: BreakDictionary, BreakIterator, BreakIteratorFactory, DictionaryBasedBreakIterator, Normalizer, Replaceable, ReplaceableString, text.RuleBasedBreakIterator, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: RangeValueIterator, ValueIterator, VersionInfo
Basic Properties propertiesBasic, propertiesBasicTests com.ibm.icu.dev.test.lang 518 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript, UScriptRun
icu.text: BreakDictionary, BreakIterator, BreakIteratorFactory, DictionaryBasedBreakIterator, Normalizer, Replaceable, ReplaceableString, RuleBasedBreakIterator, SymbolTable, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: CompactByteArray, RangeValueIterator, ValueIterator, VersionInfo
Full Properties propertiesFull, propertiesFullTests com.ibm.icu.dev.test.lang 1,610 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript, UScriptRun
icu.text: BreakDictionary, BreakIterator, BreakIteratorFactory, DictionaryBasedBreakIterator, Normalizer, Replaceable, ReplaceableString, RuleBasedBreakIterator, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: RangeValueIterator, ValueIterator, VersionInfo
Formatting format, formatTests com.ibm.icu.dev.test.format 2,645 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript
icu.math: math.BigDecimal
icu.text: BreakIterator, CanonicalIterator, ChineseDateFormat, ChineseDateFormatSymbols, CollationElementIterator, CollationKey, CollationParsedRuleBuilder, CollationRuleParser, Collator, CollatorReader, DateFormat, DateFormatSymbols, DecimalFormat, DecimalFormatSymbols, Normalizer, NumberFormat, Replaceable, ReplaceableString, RuleBasedCollator, RuleBasedNumberFormat, SimpleDateFormat, UCharacterIterator, UForwardCharacterIterator, UnicodeFilter, UnicodeMatcher, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: Calendar, CalendarAstronomer, CalendarCache, CalendarFactory, ChineseCalendar, Currency, GregorianCalendar, RangeValueIterator, SimpleTimeZone, SimpleTimeZoneAdapter, TimeZone, TimeZoneData, ValueIterator,VersionInfo
StringPrep, IDNA stringPrep, stringPrepTests com.ibm.icu.dev.test.stringprep 466 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript
icu.text: BreakIterator, CanonicalIterator, IDNA, Normalizer, Replaceable, ReplaceableString, StringPrep, StringParseException, UCharacterIterator, UForwardCharacterIterator, UnicodeSet, UTF16
icu.util: RangeValueIterator, StringTokenizer, ULocale, UResourceBundle ValueIterator,VersionInfo
Transforms transliterator, transliteratorTests com.ibm.icu.dev.test.translit 836 KB
icu.lang: UCharacter, UCharacterCategory, UCharacterDirection, UCharacterNameIterator, UCharacterTypeIterator, UProperty, UScript, UScriptRun
icu.text: AnyTransliterator, BreakDictionary, BreakIterator, BreakIteratorFactory, BreakTransliterator, DictionaryBasedBreakIterator, Normalizer, Replaceable, ReplaceableString, RuleBasedBreakIterator, StringReplacer, Transliterator, UCharacterIterator, UForwardCharacterIterator, UnicodeSet, UnicodeSetIterator, UTF16
icu.util: RangeValueIterator, ValueIterator, VersionInfo

Building any of these modules is as easy as specifying a build target to the Ant build system, e.g:
To build a module that contains only the Normalizer API:

  1. Build the module.
    ant normalizer
  2. Build the jar containing the module.
    ant moduleJar
  3. Build the tests for the module.
    ant normalizerTests
  4. Run the tests and verify that the self tests pass.
    java -classpath $icu4j_root/classes com.ibm.icu.dev.test.TestAll -nothrow -w
If more than one module is required, the module build targets can be concatenated, e.g:
  1. Build the modules.
    ant normalizer collator
  2. Build the jar containing the modules.
    ant moduleJar
  3. Build the tests for the module.
    ant normalizerTests collatorTests
  4. Run the tests and verify that they pass.
    java -classpath $icu4j_root/classes com.ibm.icu.dev.test.TestAll -nothrow -w
The jar should be built before the tests, since for some targets building the tests will cause additional classes to be compiled that are not strictly necessary for the module itself.
Notes:

Trying Out ICU4J

Note: the demos provided with ICU4J are for the most part undocumented. This list can show you where to look, but you'll have to experiment a bit. The demos (with the exception of richedit) are unsupported and may change or disappear without notice.

The icu4j.jar file contains only the core ICU4J classes, not the demo classes, so unless you build ICU4J there is little to try out.

Rich Edit

To try out the richedit package, first build the richeditJar target. This is a 'runnable' jar file. To run the richedit demo, type:
java -jar $Root/richedit/richedit.jar
This will present an empty edit pane with an awt interface.

With a fuller command line you can try out other options, for example:

java -classpath $Root/richedit/richedit.jar com.ibm.richtext.demo.EditDemo [-swing][file]
This will use an awt GUI, or a swing GUI if -swing is passed on the command line. It will open a text file if one is provided, otherwise it will open a blank page. Click to type.

You can add tabs to the tab ruler by clicking in the ruler while holding down the control key. Clicking on an existing tab changes between left, right, center, and decimal tabs. Dragging a tab moves it, dragging it off the ruler removes it.

You can experiment with complex text by using the keymap functions. Please note that these are mainly for demo purposes, for real work with Arabic or Hebrew you will want to use an input method. You will need to use a font that supports Arabic or Hebrew, 'Lucida Sans' (provided with Java) supports these languages.

Other demos

The other demo programs are not supported and exist only to let you experiment with the ICU4J classes. First, build ICU4J using ant all. Then try one of the following:

ICU4J Resource Information

Starting with release 2.1, ICU4J includes its own resource information which is completely independent of the JDK resource information. The new ICU4J information is equivalent to the information in ICU4C and many resources are, in fact, the same binary files that ICU4C uses.

By default the ICU4J distribution includes all of the standard resource information. It is located under the directory com/ibm/icu/impl/data. Depending on the service, the data is in different locations and in different formats. Note: This will continue to change from release to release, so clients should not depend on the exact organization of the data in ICU4J.

Some of the data files alias or otherwise reference data from other data files. One reason for this is because some locale names have changed. For example, he_IL used to be iw_IL. In order to support both names but not duplicate the data, one of the resource files refers to the other file's data. In other cases, a file may alias a portion of another file's data in order to save space. Currently ICU4J provides no tool for revealing these dependencies.

Note: Java's Locale class silently converts the language code "he" to "iw" when you construct the Locale. Thus Java cannot be used to locate resources that use the "he" language code. ICU, on the other hand, does not perform this conversion in ULocale, and instead uses aliasing in the locale data to represent the same set of data under different locale ids.

Resource files that use locale ids form a hierarchy, with up to four levels: a root, language, region (country), and variant. Searches for locale data attempt to match as far down the hierarchy as possible, for example, "he_IL" will match he_IL, but "he_US" will match he (since there is no US variant for he, and "xx_YY will match root (the default fallback locale) since there is no xx language code in the locale hierarchy. Again, see java.util.ResourceBundle for more information.

Currently ICU4J provides no tool for revealing these dependencies between data files, so trimming the data directly in the ICU4J project is a hit-or-miss affair. The key point when you remove data is to make sure to remove all dependencies on that data as well. For example, if you remove he.res, you need to remove he_IL.res, since it is lower in the hierarchy, and you must remove iw.res, since it references he.res, and iw_IL.res, since it depends on it (and also references he_IL.res).

Unfortunately, the jar tool in the JDK provides no way to remove items from a jar file. Thus you have to extract the resources, remove the ones you don't want, and then create a new jar file with the remining resources. See the jar tool information for how to do this. Before 'rejaring' the files, be sure to thoroughly test your application with the remaining resources, making sure each required resource is present.

Using additional resource files with ICU4J

Warning: Resource file formats can change across releases of ICU4J!
The format of ICU4J resources is not part of the API. Clients who develop their own resources for use with ICU4J should be prepared to regenerate them when they move to new releases of ICU4J.

ICU4J 3.0's resource mechanism is new for this release and we are still developing it. Currently it is not possible to mix icu's new binary .res resources with traditional java-style .class or .txt resources. We might allow for this in a future release, but since the resource data and format is not formally supported, you run the risk of incompatibilities with future releases of ICU4J.

Resource data in ICU4J is checked in to the repository as a jar file containing the resource binaries, icudata.jar. This means that inspecting the contents of these resources is difficult. They currently are compiled from ICU4C .txt file data. You can view the contents of the ICU4C text resource files to understand the contents of the ICU4J resources.

The files in icudata.jar get extracted to com/ibm/icu/impl/data in the build directory when the 'core' target is built. Thereafter, as long as the file res_index.res file is untouched, they will not be extracted again. Building the 'resources' target will force the resources to once again be extracted. Extraction will overwrite any corresponding resource files already in that directory.

Building ICU4J Resources from ICU4C

Requirements
Procedure
  1. Download and build ICU on a Windows machine. For instructions on downloading and building ICU, please click here.
  2. Change directory to $icu_root/source/tools/genrb
  3. Launch gendtjar.pl from that directory itself with the command
    gendtjar.pl --icu-root=$icu_root --jar=$jdk_home/bin --icu4j-root=$icu4j_root --version=$icu_version
    e.g: gendtjar.pl --icu-root=\work\icu --jar=\jdk1.4.1\bin --icu4j-root=\work\icu4j --version=3.0
    Execution of gendtjar.pl script will create the required jar files in the $icu_root\source\tools\genrb\temp directory.
  4. Move icudata.jar to $icu4j_root/src/com/ibm/icu/impl/data directory.
  5. Move testdata.jar to $icu4j_root/src/com/ibm/dev/data directory.
  6. Build resources target of ant to unpack the jar files with the following command.
    $ant_home/bin/ant resources

Where to Find More Information

http://oss.software.ibm.com/icu4j/ is a pointer to general information about the International Components for Unicode in Java

http://www.ibm.com/developer/unicode is a pointer to information on how to make applications global.

Submitting Comments, Requesting Features and Reporting Bugs

Your comments are important to making ICU4J successful.  We are committed to fixing any bugs, and will use your feedback to help plan future releases.

To submit comments, request features and report bugs, contact us through the ICU4J mailing list.
While we are not able to respond individually to each comment, we do review all comments.



Thank you for your interest in ICU4J!


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