1.3 Practice

Previous authors of concurrent programming textbooks have been hampered by the lack of a widely available and generally accepted programming language with concurrency features. Java meets the criteria of availability and acceptance and has the advantage of being a general-purpose language with concurrency rather than a special-purpose language of restricted applicability. Consequently, we use Java exclusively as the language for programming examples. The simplicity of the concurrency features in Java is an advantage since more complex concurrency abstractions can be constructed and packaged as classes.

The full source of the set of example programs presented in the book is provided with the book and is available on the Web. In addition, all of the example programs may be run as applets in Web browsers. We believe that the ability to execute the programs is a significant aid to understanding the issues involved. The controls embedded in most of the example programs enable different execution scenarios to be set up, facilitating “what if” questions to be asked of the programs. The satisfaction of seeing (and experiencing) rather than merely believing is important in sustaining both interest and comprehension. This is as true for self-study as it is for formally taught courses.

The availability of Java on a wide range of platforms means that most readers will be able to treat both the modeling and programming problems included in the book as implementation rather than purely pen-and-paper exercises. In many of the problems a graphical interface is already provided so that the reader can concentrate on the concurrent programming component of the problem.

We make no apologies for including in the set of examples and exercises those that are sometimes disparagingly referred to as “toy problems”. Typical of this class of example is the Dining Philosophers problem. The authors regard these examples as being valuable in condensing and crystallizing particular concurrent programming problems. They let the reader concentrate on the concurrency issues without the burden of understanding the application context. These examples are widely used in the literature on concurrent programming as a means of comparing different concurrent programming languages and constructs.