All of Java's Input/Output (I/O) facilities are based on streams, which provide simple ways to read and write data of different types. Java provides many different kinds of streams, each with its own application. The universe of streams is divided into four large categories: input streams and output streams, for reading and writing binary data; and readers and writers, for reading and writing textual (character) data. You're almost certainly familiar with the basic kinds of streams--but did you know that there's a CipherInputStream for reading encrypted data? And a ZipOutputStream for automatically compressing data? Do you know how to use buffered streams effectively to make your I/O operations more efficient? Java I/O, 2nd Edition has been updated for Java 5.0 APIs and tells you all you ever need to know about streams--and probably more.

A discussion of I/O wouldn't be complete without treatment of character sets and formatting. Java supports the Unicode standard, which provides definitions for the character sets of most written languages. Consequently, Java is the first programming language that lets you do I/O in virtually any language. Java also provides a sophisticated model for formatting textual and numeric data. Java I/O, 2nd Edition shows you how to control number formatting, use characters aside from the standard (but outdated) ASCII character set, and get a head start on writing truly multilingual software.

Java I/O, 2nd Edition includes:

• Coverage of all I/O classes and related classes
• In-depth coverage of Java's number formatting facilities and its support for international character sets

The book opens with an overview of Java's stream capabilities. (The author defends Java's lack of support for console input/output (I/O) since today's applications use graphical user interfaces anyway.) He shows how to open, read, and write local files in Java applications. His file viewer example presents data in a variety of formats. (This example is improved several times until it winds up supporting different international character sets by the end of the book.)

Next the author covers network programming using URL and network streams, including sockets. Sections on filters show how classes can filter out characters within streams. The tour moves forward to cover data streams, which permit streaming of Java's primitive data types. Details on how to communicate within Java programs using pipes follow. In a notable chapter, the author thoroughly explicates Java's support for encryption, including hashing, the Data Encryption Standard (DES) algorithm, and ciphers.

The last portion of the book explains object serialization, which allows Java objects to save and restore their state, plus it includes sections on Java's support for data compression (and ZIP files) and multilingual Unicode character sets. (Java is prepared to handle virtually any of the world's languages with its reader and writer classes.) Finally, the author shows how you can format output in Java using its support for width and numeric precision APIs.

In all, Elliotte makes a good case that Java streams are a flexible and powerful part of the language, and certainly not a limitation. --Richard Dragan