A.  Java Encoding Schemes

Appendix A

Java Encoding Schemes

This appendix describes the character-encoding schemes that are supported by the Java platform.

US-ASCII

US-ASCII is a 7-bit character set and encoding that covers the English-language alphabet.It is not large enough to cover the characters used in other languages,however, so it is not very useful for internationalization.

ISO-8859-1

ISO-8859-1 is the character set for Western European languages. It’s an 8-bit encodingscheme in which every encoded character takes exactly 8 bits. (With the remainingcharacter sets, on the other hand, some codes are reserved to signal thestart of a multibyte character.)

UTF-8

UTF-8 is an 8-bit encoding scheme. Characters from the English-language alphabet are allencoded using an 8-bit byte. Characters for other languages are encoded using 2,3, or even 4 bytes. UTF-8 therefore produces compact documents for the Englishlanguage, but for other languages, documents tend to be half again as largeas they would be if they used UTF-16. If the majority of adocument’s text is in a Western European language, then UTF-8 is generally agood choice because it allows for internationalization while still minimizing the space requiredfor encoding.

UTF-16

UTF-16 is a 16-bit encoding scheme. It is large enough to encode allthe characters from all the alphabets in the world. It uses 16bits for most characters but includes 32-bit characters for ideogram-based languages such as Chinese.A Western European-language document that uses UTF-16 will be twice as large asthe same document encoded using UTF-8. But documents written in far Eastern languageswill be far smaller using UTF-16.

Note -UTF-16 depends on the system’s byte-ordering conventions. Although in most systems, high-order bytesfollow low-order bytes in a 16-bit or 32-bit “word,” some systems use thereverse order. UTF-16 documents cannot be interchanged between such systems without a conversion.

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