Sams Teach Yourself Java 2 in 21 Days, Professional Reference Edition

Rogers Cadenhead Laura Lemay Teach Yourself Java 2 ™ in 21 Days PROFESSIONAL REFERENCE EDITION THIRD EDITION 800 E...

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Rogers Cadenhead Laura Lemay

Teach Yourself

Java 2 ™

in

21 Days

PROFESSIONAL REFERENCE EDITION THIRD EDITION 800 East 96th St., Indianapolis, Indiana, 46240 USA

Sams Teach Yourself Java 2 in 21 Days, Professional Reference Edition Third Edition

ACQUISITIONS EDITOR

Copyright © 2003 by Sams Publishing

MANAGING EDITOR

All rights reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book, the publisher and author assume no responsibility for errors or omissions. Nor is any liability assumed for damages resulting from the use of the information contained herein. International Standard Book Number: 0-672-32455-5 Library of Congress Catalog Card Number: 2002106467 Printed in the United States of America First Printing: December 2002 06

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Trademarks All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Sams Publishing cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark.

Warning and Disclaimer Every effort has been made to make this book as complete and as accurate as possible, but no warranty or fitness is implied. The information provided is on an “as is” basis. The author and the publisher shall have neither liability nor responsibility to any person or entity with respect to any loss or damages arising from the information contained in this book or from the use of the CD or programs accompanying it.

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Kathryn Purdum

DEVELOPMENT EDITOR Scott Meyers Charlotte Clapp

INDEXER Sandy Henselmeier

TECHNICAL EDITOR John Purdum

INTERIOR DESIGNER Gary Adair

COVER DESIGNER Aren Howell

PAGE LAYOUT Ayanna Lacey

Contents at a Glance Introduction WEEK 1 The Java Language

1 7

1

Getting Started with Java

2

The ABCs of Programming

37

3

Working with Objects

63

4

Lists, Logic, and Loops

5

Creating Classes and Methods

6

Packages, Interfaces, and Other Class Features

141

7

Threads and Exceptions

179

WEEK 2 The Java Class Library

9

85 111

209

8

Data Structures and Strings

211

9

Working with Swing

233

10

Building a Swing Interface

261

11

Arranging Components on a User Interface

289

12

Responding to User Input

315

13

Color, Fonts, and Graphics

343

14

Writing Java Applets

365

WEEK 3 Java Programming

393

15

Working with Inputand Output

395

16

Serializing and Examining Objects

423

17

Communicating Across the Internet

449

18

JavaSound

483

19

Creating and Using JavaBeans

503

20

Reading and Writing Data Using JDBC

523

21

Reading and Writing XML Data

547

BONUS WEEK Advanced Java Programming

567

22

Writing Java Servlets

569

23

JavaServer Pages

587

24

Writing Java 1.0 Applets

607

25

Accessibility

631

26

Java Web Start

649

27

Creating Web Services with XML-RPC

667

28

Regular Expressions

685

Appendixes Appendix A

701

Choosing Java

703

B

Using the Java 2 Software Development Kit

715

C

Programming with the Java 2 Software Development Kit

739

D

Using Sun ONE Studio

763

E

Where to Go from Here: Java Resources

775

F

This Book’s Web Site

783

Index

785

Table of Contents Introduction

WEEK 1 The Java Language Day 1 Getting Started with Java

1

7 9

The Java Language ................................................................................................10 History of the Language ..................................................................................10 Introduction to Java ..........................................................................................11 Selecting a Development Tool..........................................................................12 Object-Oriented Programming ..............................................................................13 Objects and Classes ..............................................................................................15 Object Reuse ....................................................................................................16 Attributes and Behavior ........................................................................................17 Attributes of a Class of Objects ......................................................................18 Behavior of a Class of Objects ........................................................................19 Creating a Class................................................................................................19 Running the Program........................................................................................21 Organizing Classes and Class Behavior ................................................................24 Inheritance ........................................................................................................25 Creating a Class Hierarchy ..............................................................................27 Inheritance in Action ........................................................................................29 Single and Multiple Inheritance ......................................................................30 Interfaces ..........................................................................................................31 Packages ..........................................................................................................31 Summary ................................................................................................................32 Q&A ......................................................................................................................33 Quiz........................................................................................................................34 Questions ..........................................................................................................34 Answers ............................................................................................................34 Certification Practice ........................................................................................35 Exercises ................................................................................................................35 Day 2 The ABCs of Programming

37

Statements and Expressions ..................................................................................38 Variables and Data Types ......................................................................................39 Creating Variables ............................................................................................39 Naming Variables..............................................................................................41 Variable Types ..................................................................................................41 Assigning Values to Variables ..........................................................................43 Constants ..........................................................................................................43

vi

Sams Teach Yourself Java 2 in 21 Days, Professional Reference Edition

Comments ..............................................................................................................44 Literals ..................................................................................................................45 Number Literals................................................................................................46 Boolean Literals................................................................................................47 Character Literals ............................................................................................47 String Literals ..................................................................................................48 Expressions and Operators ....................................................................................49 Arithmetic ........................................................................................................49 More About Assignment ..................................................................................51 Incrementing and Decrementing ......................................................................52 Comparisons ....................................................................................................54 Logical Operators ............................................................................................54 Operator Precedence ........................................................................................55 String Arithmetic....................................................................................................57 Summary ................................................................................................................58 Q&A ......................................................................................................................59 Quiz........................................................................................................................60 Questions ..........................................................................................................60 Answers ............................................................................................................60 Certification Practice ........................................................................................61 Exercises ................................................................................................................61 Day 3 Working with Objects

63

Creating New Objects............................................................................................63 Using new ..........................................................................................................64 What new Does ................................................................................................66 A Note on Memory Management ....................................................................66 Accessing and Setting Class and Instance Variables ............................................67 Getting Values ..................................................................................................67 Changing Values ..............................................................................................68 Class Variables..................................................................................................69 Calling Methods ....................................................................................................70 Nesting Method Calls ......................................................................................71 Class Methods ..................................................................................................72 References to Objects ............................................................................................73 Casting and Converting Objects and Primitive Types ..........................................75 Casting Primitive Types....................................................................................76 Casting Objects ................................................................................................77 Converting Primitive Types to Objects and Vice Versa....................................78 Comparing Object Values and Classes ..................................................................79 Comparing Objects ..........................................................................................79 Determining the Class of an Object ................................................................81 Summary ................................................................................................................81

Contents

vii

Q&A ......................................................................................................................82 Quiz........................................................................................................................83 Questions ..........................................................................................................83 Answers ............................................................................................................83 Certification Practice ........................................................................................83 Exercises ................................................................................................................84 Day 4 Lists, Logic, and Loops

85

Arrays ....................................................................................................................85 Declaring Array Variables ................................................................................86 Creating Array Objects ....................................................................................87 Accessing Array Elements................................................................................88 Changing Array Elements ................................................................................89 Multidimensional Arrays ..................................................................................91 Block Statements ..................................................................................................92 if Conditionals ......................................................................................................93 switch Conditionals ..............................................................................................94 for Loops ..............................................................................................................99 while and do Loops ............................................................................................102 while Loops....................................................................................................102 do...while Loops ..........................................................................................104 Breaking Out of Loops ........................................................................................105 Labeled Loops ................................................................................................105 The Conditional Operator ..............................................................................106 Summary ..............................................................................................................107 Q&A ....................................................................................................................107 Quiz......................................................................................................................108 Questions ........................................................................................................108 Answers ..........................................................................................................108 Certification Practice ......................................................................................109 Exercises ..............................................................................................................109 Day 5 Creating Classes and Methods

111

Defining Classes ..................................................................................................112 Creating Instance and Class Variables ................................................................112 Defining Instance Variables............................................................................112 Class Variables................................................................................................113 Creating Methods ................................................................................................113 Defining Methods ..........................................................................................114 The this Keyword..........................................................................................116 Variable Scope and Method Definitions ........................................................116 Passing Arguments to Methods ......................................................................118 Class Methods ................................................................................................119

viii

Sams Teach Yourself Java 2 in 21 Days, Professional Reference Edition

Creating Java Applications ..................................................................................121 Helper Classes ................................................................................................122 Java Applications and Command-Line Arguments ............................................122 Passing Arguments to Java Applications........................................................122 Handling Arguments in Your Java Application ..............................................123 Creating Methods with the Same Name, Different Arguments ..........................124 Constructor Methods............................................................................................128 Basic Constructors Methods ..........................................................................129 Calling Another Constructor Method ............................................................129 Overloading Constructor Methods ................................................................130 Overriding Methods ............................................................................................132 Creating Methods That Override Existing Methods ......................................132 Calling the Original Method ..........................................................................134 Overriding Constructors ................................................................................134 Finalizer Methods ................................................................................................136 Summary ..............................................................................................................137 Q&A ....................................................................................................................137 Quiz......................................................................................................................138 Questions ........................................................................................................138 Answers ..........................................................................................................139 Certification Practice ......................................................................................139 Exercises ..............................................................................................................140 Day 6 Packages, Interfaces, and Other Class Features

141

Modifiers..............................................................................................................142 Access Control for Methods and Variables ....................................................143 Static Variables and Methods ..............................................................................148 Final Classes, Methods, and Variables ................................................................150 Variables ........................................................................................................151 Methods ..........................................................................................................151 Classes ............................................................................................................152 Abstract Classes and Methods ............................................................................152 Packages ..............................................................................................................153 Using Packages ....................................................................................................154 Full Package and Class Names ......................................................................154 The import Declaration..................................................................................155 Name Conflicts ..............................................................................................156 A Note About CLASSPATH and Where Classes Are Located ..........................157 Creating Your Own Packages ..............................................................................157 Picking a Package Name ................................................................................158 Creating the Folder Structure ........................................................................158 Adding a Class to a Package ..........................................................................159 Packages and Class Access Control ..............................................................159

Contents

ix

Interfaces..............................................................................................................160 The Problem of Single Inheritance ................................................................160 Interfaces and Classes ....................................................................................161 Implementing and Using Interfaces ..............................................................161 Implementing Multiple Interfaces ..................................................................163 Other Uses of Interfaces ................................................................................163 Creating and Extending Interfaces ......................................................................164 New Interfaces................................................................................................164 Methods Inside Interfaces ..............................................................................165 Extending Interfaces ......................................................................................166 Creating an Online Storefront ........................................................................167 Inner Classes ........................................................................................................173 Summary ..............................................................................................................175 Q&A ....................................................................................................................175 Quiz......................................................................................................................176 Questions ........................................................................................................176 Answers ..........................................................................................................176 Certification Practice ......................................................................................177 Exercises ..............................................................................................................178 Day 7 Threads and Exceptions

179

Exceptions............................................................................................................180 Exception Classes ..........................................................................................182 Managing Exceptions ..........................................................................................183 Exception Consistency Checking ..................................................................183 Protecting Code and Catching Exceptions ....................................................184 The finally Clause........................................................................................186 Declaring Methods That Might Throw Exceptions ............................................188 The throws Clause..........................................................................................188 Which Exceptions Should You Throw?..........................................................189 Passing on Exceptions ....................................................................................190 throws and Inheritance ..................................................................................191 Creating and Throwing Your Own Exceptions....................................................192 Throwing Exceptions......................................................................................192 Creating Your Own Exceptions ......................................................................193 Combining throws, try, and throw ................................................................193 When to and When Not to Use Exceptions ........................................................194 When to Use Exceptions ................................................................................194 When Not to Use Exceptions ........................................................................195 Bad Style Using Exceptions ..........................................................................195 Assertions ............................................................................................................196

x

Sams Teach Yourself Java 2 in 21 Days, Professional Reference Edition

Threads ................................................................................................................198 Writing a Threaded Program..........................................................................198 A Threaded Application ................................................................................200 Stopping a Thread ..........................................................................................204 Summary ..............................................................................................................205 Q&A ....................................................................................................................206 Quiz......................................................................................................................207 Questions ........................................................................................................207 Answers ..........................................................................................................207 Certification Practice ......................................................................................207 Exercises ..............................................................................................................208

WEEK 2 The Java Class Library Day 8 Data Structures and Strings

209 211

Data Structures ....................................................................................................211 Java Data Structures ............................................................................................212 Iterator ........................................................................................................214 Bit Sets............................................................................................................215 Vectors ............................................................................................................218 Stacks..............................................................................................................221 Map ................................................................................................................223 Hash Tables ....................................................................................................224 Summary ..............................................................................................................229 Q&A ....................................................................................................................230 Quiz......................................................................................................................230 Questions ........................................................................................................230 Answers ..........................................................................................................231 Certification Practice ......................................................................................231 Exercises ..............................................................................................................232 Day 9 Working with Swing

233

Creating an Application ......................................................................................234 Creating an Interface ......................................................................................235 Developing a Framework ..............................................................................237 Closing a Window ..........................................................................................240 Creating a Component....................................................................................242 Adding Components to a Container ..............................................................243 Working with Components ..................................................................................245 Image Icons ....................................................................................................245 Labels..............................................................................................................247 Text Fields ......................................................................................................248 Text Areas ......................................................................................................249 Scrolling Panes ..............................................................................................251

Contents

xi

Scrollbars ........................................................................................................251 Check Boxes and Radio Buttons....................................................................252 Drop-Down Lists and Combo Boxes ............................................................255 Summary ..............................................................................................................257 Q&A ....................................................................................................................257 Quiz......................................................................................................................258 Questions ........................................................................................................258 Answers ..........................................................................................................259 Certification Practice ......................................................................................259 Exercises ..............................................................................................................260 Day 10 Building a Swing Interface

261

Swing Features ....................................................................................................262 Setting the Look and Feel ..............................................................................262 Standard Dialog Boxes ..................................................................................265 An Example: The Info Application ..............................................................269 Sliders ............................................................................................................272 Scroll Panes ....................................................................................................274 Toolbars ..........................................................................................................276 Progress Bars ..................................................................................................278 Menus ............................................................................................................281 Tabbed Panes ..................................................................................................283 Summary ..............................................................................................................284 Q&A ....................................................................................................................285 Quiz......................................................................................................................285 Questions ........................................................................................................285 Answers ..........................................................................................................286 Certification Practice ......................................................................................286 Exercises ..............................................................................................................287 Day 11 Arranging Components on a User Interface

289

Basic Interface Layout ........................................................................................290 Laying Out an Interface..................................................................................290 Flow Layout....................................................................................................291 Grid Layout ....................................................................................................293 Border Layout ................................................................................................295 Mixing Layout Managers ....................................................................................297 Card Layout ........................................................................................................297 Grid Bag Layout ..................................................................................................299 Designing the Grid ........................................................................................300 Creating the Grid ............................................................................................301 Determining the Proportions ..........................................................................304 Adding and Arranging the Components ........................................................306 Making Adjustments ......................................................................................308

xii

Sams Teach Yourself Java 2 in 21 Days, Professional Reference Edition

Cell Padding and Insets ......................................................................................310 Summary ..............................................................................................................310 Q&A ....................................................................................................................311 Quiz......................................................................................................................312 Questions ........................................................................................................312 Answers ..........................................................................................................312 Certification Practice ......................................................................................313 Exercises ..............................................................................................................314 Day 12 Responding to User Input

315

Event Listeners ....................................................................................................315 Setting Up Components..................................................................................316 Event-Handling Methods................................................................................317 Working with Methods ........................................................................................320 Action Events ................................................................................................320 Adjustment Events..........................................................................................321 Focus Events ..................................................................................................323 Item Events ....................................................................................................323 Key Events......................................................................................................325 Mouse Events ................................................................................................326 Mouse Motion Events ....................................................................................326 Window Events ..............................................................................................327 Creating a Swing Application..............................................................................327 Designing the Layout ....................................................................................328 Defining the Subpanels ..................................................................................330 Converting Between sRGB and HSB ............................................................332 Handling User Events ....................................................................................335 Summary ..............................................................................................................339 Q&A ....................................................................................................................339 Quiz......................................................................................................................340 Questions ........................................................................................................340 Answers ..........................................................................................................341 Certification Practice ......................................................................................341 Exercises ..............................................................................................................342 Day 13 Color, Fonts, and Graphics

343

The Graphics2D Class..........................................................................................343 The Graphics Coordinate System ..................................................................345 Drawing Text........................................................................................................346 Finding Information About a Font ................................................................347 Color ....................................................................................................................349 Using Color Objects ......................................................................................350 Testing and Setting the Current Colors ..........................................................351

Contents

xiii

Drawing Lines and Polygons ..............................................................................352 User and Device Coordinate Spaces ..............................................................352 Specifying the Rendering Attributes ..............................................................353 Creating Objects to Draw ..............................................................................355 Drawing Objects ............................................................................................358 Summary ..............................................................................................................361 Q&A ....................................................................................................................362 Quiz......................................................................................................................362 Questions ........................................................................................................362 Answers ..........................................................................................................363 Certification Practice ......................................................................................363 Exercises ..............................................................................................................364 Day 14 Writing Java Applets

365

How Applets and Applications Are Different......................................................366 Applet Security Restrictions ................................................................................366 Choosing a Java Version ................................................................................367 Creating Applets ..................................................................................................369 Major Applet Activities ..................................................................................369 An Example Applet ........................................................................................373 Including an Applet on a Web Page ....................................................................375 The <APPLET> Tag ..........................................................................................376 Loading an Applet ..........................................................................................380 The

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