Java Threads, Second Edition

Chapter 1. Introduction to Threading

This is a book about using threads in the Java programming language and the Java virtual machine. The topic of threads is very important in Java—so important that many features of a threaded system are built into the Java language itself, while other features of a threaded system are required by the Java virtual machine. Threading is an integral part of using Java.

The concept of threads is not a new one: for some time, many operating systems have had libraries that provide the C programmer with a mechanism to create threads. Other languages, such as Ada, have support for threads embedded into the language, much as support for threads is built into the Java language. Nonetheless, the topic of threads is usually considered a peripheral programming topic, one that’s only needed in special programming cases.

With Java, things are different: it is impossible to write any but the simplest Java program without introducing the topic of threads. And the popularity of Java ensures that many developers who might never have considered learning about threading possibilities in a language like C or C++ need to become fluent in threaded programming.

Java Terms

We’ll start by defining some terms used throughout this book. Many terms surrounding Java are used inconsistently in various sources; we’ll endeavor to be consistent in our usage of these terms throughout the book.

Java

First is the term Java itself. As we know, Java started out as a programming language, ...