Introduction

Java provides a consistent framework for all input/output. That framework centers on the concept of a stream. A stream in Java is a sequential flow of bytes in one direction. There is an output stream that carries text to the console and a corresponding input stream that brings text from the keyboard. Another type of output stream carries data to a file, and a corresponding input stream brings data into a program from a file. There is another output stream that sends data through a network port to another computer on the network while an input stream brings in data through a network port from such a source.

The bulk of Java I/O classes belong to the java.io package. (See pediagram in Figure 9.1.) The class hierarchy builds on the base classes InputStream, OutputStream, Reader, and Writer to provide a wide range of input and output tasks. In addition, this package holds stream classes that wrap a stream to add more capabilities to it. Some I/O classes provide a destination or source, such as a file or an array. Others process the stream in some way such as buffering or filtering the data.

Packages involving I/O include:

• java.io – the primary Java I/O classes

• java.nio, java.nio.* – a set of five packages new with Java 1.4 based on the concept of channels that represent an open connection to a hardware device, file, or other entity. Channels don't supplant streams but rather work with them to add additional capabilities and enhanced scaling when working with large numbers of connections

• […]