Chapter 3. Input/Output

A computer program isn't much good unless it can communicate with the outside world, and input/output (I/O) capabilities are a fundamental feature of any programming platform. In Java, I/O is done with the classes and interfaces of the java.io package and, in Java 1.4, with the "New IO" package java.nio and its subpackages. This chapter demonstrates the input/output capabilities of java.io. The New I/O API is covered in Chapter 6. The examples here demonstrate how to:

• Read and write files

• List directories and obtain file size and date information

• Use various Java stream classes

• Define customized stream subclasses

The techniques introduced in this chapter are also used in other places in this book. We'll see many examples that use streams for input and output in Chapter 5, and we'll see a specialized kind of I/O in Chapter 10.