Java Cookbook, 2nd Edition

Chapter 10. Input and Output

Introduction

Most programs need to interact with the outside world, and one common way of doing so is by reading and writing files. Files are normally on some persistent medium such as a disk drive, and, for the most part, we shall happily ignore the differences between a hard disk (and all the operating system-dependent filesystem types), a floppy or zip drive, a CD-ROM, and others. For now, they’re just files.

This chapter covers all the normal input/output operations such as opening/closing and reading/writing files. Files are assumed to reside on some kind of file store or permanent storage. I don’t discuss how such a filesystem or disk I/O system works—consult a book on operating system design or a platform-specific book on system internals or filesystem design. Network filesystems such as Sun’s Network File System (NFS, common on Unix and available for Windows through products such as Hummingbird NFS Maestro), Macintosh Appletalk File System (used for OS 9; available for Unix via the open source Netatalk), and SMB (Windows network filesystem, available for Unix with the open source Samba program) are assumed to work “just like” disk filesystems, except where noted.

JDK 1.5 introduced the Formatter and Scanner classes, which provide substantial new functionality. Formatter allows many formatting tasks to be performed either into a String or to almost any output destination. Scanner parses many kinds of objects, again either from a String or from ...