Steven John Metsker - Design patterns in Java, 2nd Edition

Series Editor: John M. Vlissides

The Software Patterns Series (SPS) comprises pattern literature of lasting significance to software developers. Software patterns document general solutions to recurring problems in all software-related spheres, from the technology itself, to the organizations that develop and distribute it, to the people who use it. Books in the series distill experience from one or more of these areas into a form that software professionals can apply immediately.

Relevance and impact are the tenets of the SPS. Relevance means each book presents patterns that solve real problems. Patterns worthy of the name are intrinsically relevant; they are borne of practitioners experiences, not theory or speculation. Patterns have impact when they change how people work for the better. A book becomes a part of the series not just because it embraces these tenets, but because it has demonstrated it fulfills them for its audience.

Titles in the series:

Data Access Patterns: Database Interactions in Object-Oriented Applications;Clifton Nock

Design Patterns Explained, Second Edition: A New Perspective on Object-Oriented Design; Alan Shalloway and James Trott

Design Patterns in C#; Steven John Metsker

Design Patterns in Java;Steven John Metsker and William C. Wake

Design Patterns Java Workbook;Steven John Metsker

.NET Patterns: Architecture, Design, and Process;Christian Thilmany

Pattern Hatching: Design Patterns Applied;John M. Vlissides

Pattern Languages of Program Design;James O. Coplien and Douglas C. Schmidt

Pattern Languages of Program Design 2;John M. Vlissides, James O. Coplien, and Norman L. Kerth

Pattern Languages of Program Design 3;Robert C. Martin, Dirk Riehle, and Frank Buschmann

Pattern Languages of Program Design 5;Dragos Manolescu, Markus Voelter, and James Noble

Patterns for Parallel Programming;Timothy G. Mattson, Beverly A. Sanders, and Berna L. Massingill

Software Configuration Management Patterns: Effective Teamwork, Practical Integration;Stephen P. Berczuk and Brad Appleton

The Design Patterns Smalltalk Companion;Sherman Alpert, Kyle Brown, and Bobby Woolf

Use Cases: Patterns and Blueprints;Gunnar vergaard and Karin Palmkvist

For more information, check out the series web site at www.awprofessional.com/series/swpatterns

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Library of Congress Cataloging-in-Publication Data

Metsker, Steven John.
Design patterns in Java / Steven John Metsker, William C. Wake.
p. cm.
Includes bibliographical references and index.
ISBN 0-321-33302-0 (hardback : alk. paper)
1. Java (Computer program language) 2. Software patterns. I. Wake, William C., 1960II. Title.
QA76.73.J38M482 2006
005.133dc22 2006003471

Copyright 2006 Pearson Education, Inc.

All rights reserved. Printed in the United States of America. This publication is protected by copyright, and permission must be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permissions, write to:

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ISBN 0-321-33302-0

Text printed in the United States on recycled paper at Courier in Westford, Massachusetts.

First printing, April 2006

To Alison, Emma-Kate, and Sarah-Jane
Steve
To May Lyn, Tyler, and Fiona
Bill

DESIGN PATTERNS ARE class- and method-level solutions to common problems in object-oriented design. If youre an intermediate-level Java programmer who wants to become advanced or an advanced-level Java programmer who hasnt yet studied design patterns, this book is for you.

Design Patterns in Java takes a workbook approach. Each chapter focuses on a particular pattern. In addition to explaining the pattern, the chapter includes a number of challenges, each asking you to explain something or to develop code that solves a problem.

We strongly urge you to stop and work through the challenges rather than try to read this book straight through. Youll learn more by putting in the work to do the challenges, even if its only a chapter or two a week.