A guide to refactoring, the process of changing a software system so that it does not alter the external behavior of the code yet improves its internal structure, for professional programmers. Early chapters cover general principles, rationales, examples, and testing. The heart of the book is a catalog of refactorings, organized in chapters on composing methods, moving features between objects, organizing data, simplifying conditional expressions, and dealing with generalizations. Later chapters describe issues in adopting refactoring in commercial development, automated tools, and the future of refactoring. Java is used for all examples. Annotation c. Book News, Inc., Portland, OR (booknews.com)