Java NIO

Chapter 1. Introduction

Get the facts first. You can distort them later.

—Mark Twain

Let’s talk about I/O. No, no, come back. It’s not really all that dull. Input/output (I/O) is not a glamorous topic, but it’s a very important one. Most programmers think of I/O in the same way they do about plumbing: undoubtedly essential, can’t live without it, but it can be unpleasant to deal with directly and may cause a big, stinky mess when not working properly. This is not a book about plumbing, but in the pages that follow, you may learn how to make your data flow a little more smoothly.

Object-oriented program design is all about encapsulation. Encapsulation is a good thing: it partitions responsibility, hides implementation details, and promotes object reuse. This partitioning and encapsulation tends to apply to programmers as well as programs. You may be a highly skilled Java programmer, creating extremely sophisticated objects and doing extraordinary things, and yet be almost entirely ignorant of some basic concepts underpinning I/O on the Java platform. In this chapter, we’ll momentarily violate your encapsulation and take a look at some low-level I/O implementation details in the hope that you can better orchestrate the multiple moving parts involved in any I/O operation.

I/O Versus CPU Time

Most programmers fancy themselves software artists, crafting clever routines to squeeze a few bytes here, unrolling a loop there, or refactoring somewhere else to consolidate objects. While those ...