Java Generics and Collections, 2nd Edition

Preface

The second edition of this book is a comprehensive update for Java 21. Since a major impetus for writing it was the introduction of sequenced collections and the earlier impact of streams and lambdas, I expected before starting work that the major changes needed would be in Part II, principally as a result of the introduction of sequenced collections. However, that was a serious underestimate of the changes that Java has undergone in the last 20 years: in fact, many revisions to Part I were also required. The language has changed; it now supports records, local variable type inference, pattern-matching expressions, and generic types in type comparison expressions. Also, most examples in Part I needed updating to take account of changes in the platform libraries, including the current deprecation of the Integer constructors, static methods on the Comparator interface, and the introduction of unmodifiable collections and of streams.

An important motivation for writing a second edition was to record some of the insights gained by the Java community in the use of both generics and collections since 2005. These are mainly contained in a retrospective section (“On the Design of Java Generics”) and two new collections chapters: Chapter 17, which provides guidance for use of the Collections Framework, and Chapter 18, which reviews the most crucial—​and also the most controversial—​decisions underlying the choices made in the design of the framework. In addition, the chapters on ...