Bluej exercise solutions chapter 6

(Objects First with Java_ A Practical Introduction Using BlueJ 6th Edition) David J. Barnes & Michael Kölling - Objects First with Java_ A Practical Introduction Using BlueJ. 6-Pearson (2016).pdf

David J. Barnes and Michael Kölling

University of Kent

Sixth Edition

Objects First with Java™

A Practical Introduction Using BlueJ

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Library of Congress Cataloging-in-Publication Data

Names: Barnes, David J. (David John), 1959 June 7- author. | Kolling, Michael, author. Title: Objects first with Java : a practical introduction using BlueJ / David J. Barnes and Michael Kolling, University of Kent. Description: Sixth edition. | Boston : Pearson Education Inc., [2017] Identifiers: LCCN 2016009911| ISBN 9780134477367 | ISBN 0134477367 Subjects: LCSH: Object-oriented programming (Computer science) | Java (Computer program language) | Computer science—Study and teaching. Classification: LCC QA76.64 .B385 2017 | DDC 005.1/17—dc23 LC record available at http://lccn.loc.gov/2016009911

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ISBN-10: 0-13-447736-7 ISBN-13: 978-0-13-447736-7

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To my wife Helen,

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To K.W.

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Foreword 14 Preface 15 List of Projects Discussed in Detail in This Book 25 Acknowledgments 28

Part 1 Foundations of Object Orientation 29

Chapter 1 Objects and Classes 31

1.1 Objects and classes 31 1.2 Creating objects 32 1.3 Calling methods 33 1.4 Parameters 34 1.5 Data types 35 1.6 Multiple instances 36 1.7 State 37 1.8 What is in an object? 38 1.9 Java code 39 1.10 Object interaction 40 1.11 Source code 41 1.12 Another example 43 1.13 Return values 43 1.14 Objects as parameters 44 1.15 Summary 45

Chapter 2 Understanding Class Definitions 49

2.1 Ticket machines 49 2.2 Examining a class definition 51 2.3 The class header 53 2.4 Fields, constructors, and methods 54 2.5 Parameters: receiving data 60 2.6 Assignment 62

Contents

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6 | Contents

2.7 Methods 63 2.8 Accessor and mutator methods 64 2.9 Printing from methods 67 2.10 Method summary 70 2.11 Summary of the naíve ticket machine 70 2.12 Reflecting on the design of the ticket machine 71 2.13 Making choices: the conditional statement 73 2.14 A further conditional-statement example 75 2.15 Scope highlighting 76 2.16 Local variables 77 2.17 Fields, parameters, and local variables 79 2.18 Summary of the better ticket machine 81 2.19 Self-review exercises 81 2.20 Reviewing a familiar example 83 2.21 Calling methods 85 2.22 Experimenting with expressions: the Code Pad 87 2.23 Summary 89

Chapter 3 Object Interaction 95

3.1 The clock example 95 3.2 Abstraction and modularization 96 3.3 Abstraction in software 97 3.4 Modularization in the clock example 97 3.5 Implementing the clock display 98 3.6 Class diagrams versus object diagrams 99 3.7 Primitive types and object types 100 3.8 The NumberDisplay class 100 3.9 The ClockDisplay class 108 3.10 Objects creating objects 111 3.11 Multiple constructors 112 3.12 Method calls 112 3.13 Another example of object interaction 116 3.14 Using a debugger 120 3.15 Method calling revisited 124 3.16 Summary 125

Chapter 4 Grouping Objects 129

4.1 Building on themes from Chapter 3 129 4.2 The collection abstraction 130

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Contents | 7

4.3 An organizer for music files 131 4.4 Using a library class 132 4.5 Object structures with collections 135 4.6 Generic classes 137 4.7 Numbering within collections 138 4.8 Playing the music files 141 4.9 Processing a whole collection 143 4.10 Indefinite iteration 148 4.11 Improving structure—the Track class 156 4.12 The Iterator type 159 4.13 Summary of the music-organizer project 163 4.14 Another example: an auction system 165 4.15 Summary 175

Chapter 5 Functional Processing of Collections (Advanced) 177

5.1 An alternative look at themes from Chapter 4 177 5.2 Monitoring animal populations 178 5.3 A first look at lambdas 182 5.4 The forEach method of collections 184 5.5 Streams 186 5.6