Java IO.pdf - Nguyen Dang Binh

Preface
Java I/O
In many ways this book is a prequel to my previous book, Java Network Programming
(O'Reilly & Associates). When writing that book, I more or less assumed that readers were
familiar with basic input and output in Java—that they knew how to use input streams and
output streams, convert bytes to characters, connect filter streams to each other, and so forth.
However, after that book was published, I began to notice that a lot of the questions I got from
readers of the book and students in my classes weren't so much about network programming
itself as they were about input and output (I/O in programmer vernacular). When Java 1.1 was
released with a vastly expanded java.io package and many new I/O classes spread out
across the rest of the class library, it became obvious that a book that specifically addressed
I/O was required. This is that book.
Java I/O endeavors to show you how to really use Java's I/O classes, allowing you to quickly
and easily write programs that accomplish many common tasks. Some of these include:
• Reading and writing files
• Communicating over network connections
• Filtering data
• Interpreting a wide variety of formats for integer and floating-point numbers
• Passing data between threads
• Encrypting and decrypting data
• Calculating digital signatures for streams
• Compressing and decompressing data
• Writing objects to streams
• Copying, moving, renaming, and getting information about files and directories
• Letting users choose files from a GUI interface
• Reading and writing non-English text in a variety of character sets
• Formatting integer and floating-point numbers as strings
• Talking directly to modems and other serial port devices
• Talking directly to printers and other parallel port devices
Java is the first language to provide a cross-platform I/O library that is powerful enough to
handle all these diverse tasks. Java I/O is the first book to fully expose the power and
sophistication of this library.
Correcting Misconceptions
Java is the first programming language with a modern, object-oriented approach to input and
output. Java's I/O model is more powerful and more suited to real-world tasks than any other
major language used today. Surprisingly, however, I/O in Java has a bad reputation. It is
widely believed (falsely) that Java I/O can't handle basic tasks that are easily accomplished in
other languages like C, C++, and Pascal. In particular, it is commonly said that:
• I/O is too complex for introductory students; or, more specifically, there's no good
way to read a number from the console.
• Java can't handle basic formatting tasks like printing with three decimal digits of
precision.
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