v
Sa
m
s.
ne
t
Le
a
rn
in
g
Ce
nt
er
abcd
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
M
T W
R
F S
S
201 West 103rd Street
Indianapolis, Indiana 46290
Laura Lemay
Charles L. Perkins
Teach Yourself
JAVA
in 21 Days
030-4 FM 1/29/96, 8:10 PM5
Note:
Click anywhere on this page to jump to the Table of Contents.
i
Sa
m
s.
ne
t
Le
a
rn
in
g
Ce
nt
er
abcd
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
W
R
F S
M T W R
About This Book
This book teaches you all about the Java language and how to use it to create
applets and applications. By the time you get through with this book, you’ll know
enough about Java to do just about anything, inside an applet or out.
Who Should Read This Book
This book is intended for people with at least some basic programming back-
ground, which includes people with years of programming experience or people
with only a small amount of experience. If you understand what variables, loops,
and functions are, you’ll be just fine for this book. The sorts of people who might
want to read this book include you, if
nn You’re a real whiz at HTML, understand CGI programming (in perl,
AppleScript, Visual Basic, or some other popular CGI language) pretty
well, and want to move on to the next level in Web page design.
nn You had some Basic or Pascal in school and you have a basic grasp of
what programming is, but you’ve heard Java is easy to learn, really
powerful, and very cool.
nn You’ve programmed C and C++ for many years, you’ve heard this Java
thing is becoming really popular and you’re wondering what all the fuss
is all about.
nn You’ve heard that Java is really good for Web-based applets, and you’re
curious about how good it is for creating more general applications.
What if you know programming, but you don’t know object-oriented program-
ming? Fear not. This book assumes no background in object-oriented design. If
you know object-oriented programming, in fact, the first couple of days will be
easy for you.
How This Book Is Structured
This book is intended to be read and absorbed over the course of three weeks.
During each week, you’ll read seven chapters that present concepts related to the
Java language and the creation of applets and applications.
030-4 FM 1/29/96, 8:10 PM1
Teach Yourself JAVA in 21 Days
M T
W T
F S
S
21
ii
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
Conventions
Note: A Note box presents interesting pieces of information related to the surround-
ing discussion.
Technical Note: A Technical Note presents specific technical information related to
the surrounding discussion.
Tip: A Tip box offers advice or teaches an easier way to do something.
Caution: A Caution box alerts you to a possible problem and gives you advice to
avoid it.
Warning: A Warning box advises you about potential problems and helps you steer
clear of disaster.
New terms are introduced in New Term boxes, with the term in italics.
A type icon identifies some new HTML code that you can type in yourself.
An Output icon highlights what the same HTML code looks like when viewed by
either Netscape or Mosaic.
An analysis icon alerts you to the author’s line-by-line analysis.
!!
Analysis
Output
Type
NEW
TERM
*
030-4 FM 1/29/96, 8:10 PM2
Teach Yourself JAVA in 21 Days
M T
W T
F S
S
21
vi
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
To Eric, for all the usual reasons
(moral support, stupid questions, comfort in dark times).
LL
For RKJP, ARL, and NMH
the three most important people in my life.
CLP
Copyright ©1996 by Sams.net
Publishing and its licensors
FIRST EDITION
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 authors assume no
responsibility for errors or omissions. Neither is any liability assumed for
damages resulting from the use of the information contained herein. For
information, address Sams.net Publishing, 201 W. 103rd St., Indianapolis,
IN 46290.
International Standard Book Number: 1-57521-030-4
Library of Congress Catalog Card Number: 95-78866
99 98 97 96 4 3 2 1
Interpretation of the printing code: the rightmost double-digit number is
the year of the book’s printing; the rightmost single-digit, the number of
the book’s printing. For example, a printing code of 96-1 shows that the
first printing of the book occurred in 1996.
Composed in AGaramond and MCPdigital by Macmillan Computer
Publishing
Printed in the United States of America
All terms mentioned in this book that are known to be trademarks or
service marks have been appropriately capitalized. Sams.net 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.
President, Sams Publishing: Richard K. Swadley
Publisher, Sams.net Publishing: George Bond
Publishing Manager: Mark Taber
Managing Editor: Cindy Morrow
Marketing Manager: John Pierce
Acquisitions Editor
Mark Taber
Development Editor
Fran Hatton
Software Development
Specialist
Merle Newlon
Production Editor
Nancy Albright
Technical Reviewer
Patrick Chan
Editorial Coordinator
Bill Whitmer
Technical Edit
Coordinator
Lynette Quinn
Formatter
Frank Sinclair
Editorial Assistant
Carol Ackerman
Cover Designer
Tim Amrhein
Book Designer
Alyssa Yesh
Production Team
Supervisor
Brad Chinn
Production
Michael Brumitt
Jason Hand
Cheryl Moore
Ayanna Lacey
Nancy Price
Bobbi Satterfield
Tim Taylor
Susan Van Ness
Mark Walchle
Todd Wente
Indexer
Tim Griffin
030-4 FM 1/29/96, 8:10 PM6
vii
Sa
m
s.
ne
t
Le
a
rn
in
g
Ce
nt
er
abcd
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
M
T W
R
F S
S
Overview
Introduction xxi
Week 1 at a Glance
Day 1 An Introduction to Java Programming 3
2 Object-Oriented Programming and Java 19
3 Java Basics 41
4 Working with Objects 61
5 Arrays, Conditionals, and Loops 79
6 Creating Classes and Applications in Java 95
7 More About Methods 111
Week 2 at a Glance
Day 8 Java Applet Basics 129
9 Graphics, Fonts, and Color 149
10 Simple Animation and Threads 173
11 More Animation, Images, and Sound 195
12 Managing Simple Events and Interactivity 217
13 User Interfaces with the Java Abstract Windowing Toolkit 237
14 Windows, Networking, and Other Tidbits 279
Week 3 at a Glance
Day 15 Modifiers 305
16 Packages and Interfaces 323
17 Exceptions 341
18 Multithreading 353
19 Streams 375
20 Native Methods and Libraries 403
21 Under the Hood 421
Appendixes
A Language Summary 473
B The Java Class Library 483
C How Java Differs from C and C++ 497
D How Java Differs from C and C++ 507
Index 511
030-4 FM 1/29/96, 8:11 PM7
ix
Sa
m
s.
ne
t
Le
a
rn
in
g
Ce
nt
er
abcd
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
M
T W
R
F S
S
Contents
Introduction xxi
Week 1 at a Glance 1
Day 1 An Introduction to Java Programming 3
What Is Java? .............................................................................................. 4
Java’s Past, Present, and Future ................................................................... 6
Why Learn Java? ......................................................................................... 7
Java Is Platform-Independent................................................................. 7
Java Is Object-Oriented ......................................................................... 9
Java Is Easy to Learn .............................................................................. 9
Getting Started with
Programming in Java .............................................................................. 10
Getting the Software ............................................................................ 10
Applets and Applications ..................................................................... 11
Creating a Java Application .................................................................. 11
Creating a Java Applet ......................................................................... 13
Summary .................................................................................................. 16
Q&A ........................................................................................................ 16
Day 2 Object-Oriented Programming and Java 19
Thinking in Objects: An Analogy ............................................................. 20
Objects and Classes .................................................................................. 21
Behavior and Attributes ............................................................................ 23
Attributes ............................................................................................. 23
Behavior .............................................................................................. 24
Creating a Class ................................................................................... 24
Inheritance, Interfaces, and Packages ........................................................ 28
Inheritance........................................................................................... 29
Creating a Class Hierarchy................................................................... 30
How Inheritance Works ...................................................................... 32
Single and Multiple Inheritance ........................................................... 34
Interfaces and Packages ........................................................................ 34
Creating a Subclass ................................................................................... 35
Summary .................................................................................................. 38
Q&A ........................................................................................................ 39
Day 3 Java Basics 41
Statements and Expressions ...................................................................... 42
Variables and Data Types ......................................................................... 43
Declaring Variables .............................................................................. 43
Notes on Variable Names .................................................................... 44
030-4 FM 1/29/96, 8:11 PM9
Teach Yourself JAVA in 21 Days
M T
W T
F S
S
21
x
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
Variable Types ..................................................................................... 45
Assigning Values to Variables ............................................................... 46
Comments ................................................................................................ 47
Literals ...................................................................................................... 47
Number Literals ................................................................................... 47
Boolean Literals ................................................................................... 48
Character Literals ................................................................................. 48
String Literals ...................................................................................... 49
Expressions and Operators ........................................................................ 50
Arithmetic ........................................................................................... 50
More About Assignment ...................................................................... 52
Incrementing and Decrementing ......................................................... 52
Comparisons ........................................................................................ 54
Logical Operators ................................................................................ 55
Bitwise Operators ................................................................................ 55
Operator Precedence ............................................................................ 56
String Arithmetic ...................................................................................... 57
Summary .................................................................................................. 58
Q&A ........................................................................................................ 60
Day 4 Working with Objects 61
Creating New Objects .............................................................................. 62
Using new ............................................................................................ 63
What new Does ................................................................................... 64
A Note on Memory Management ........................................................ 64
Accessing and Setting Class and Instance Variables ................................... 65
Getting Values ..................................................................................... 65
Changing Values .................................................................................. 65
Class Variables ..................................................................................... 66
Calling Methods ....................................................................................... 67
Class Methods ..................................................................................... 69
References to Objects ............................................................................... 70
Casting and Converting Objects and Primitive Types .............................. 71
Casting Primitive Types ...................................................................... 71
Casting Objects .................................................................................. 72
Converting Primitive Types
to Objects and Vice Versa ................................................................. 73
Odds and Ends ......................................................................................... 73
Comparing Objects ............................................................................. 74
Copying Objects .................................................................................. 75
Determining the Class of an Object ..................................................... 76
The Java Class Libraries ............................................................................ 76
Summary .................................................................................................. 77
Q&A ........................................................................................................ 78
030-4 FM 1/29/96, 8:11 PM10
xi
Sa
m
s.
ne
t
Le
a
rn
in
g
Ce
nt
er
abcd
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
Day 5 Arrays, Conditionals, and Loops 79
Arrays ....................................................................................................... 80
Declaring Array Variables .................................................................... 80
Creating Array Objects ........................................................................ 81
Accessing Array Elements ..................................................................... 81
Changing Array Elements .................................................................... 82
Multidimensional Arrays...................................................................... 83
Block Statements ...................................................................................... 83
if Conditionals .......................................................................................... 83
The Conditional Operator ................................................................... 84
switch Conditionals ................................................................................... 85
for Loops .................................................................................................. 86
while and do Loops ................................................................................... 88
while Loops .......................................................................................... 88
do...while Loops ................................................................................... 89
Breaking Out of Loops ............................................................................. 89
Labeled Loops ...................................................................................... 90
Summary .................................................................................................. 91
Q&A ........................................................................................................ 92
Day 6 Creating Classes and Applications in Java 95
Defining Classes ....................................................................................... 96
Creating Instance and Class Variables ....................................................... 96
Defining Instance Variables ................................................................. 97
Constants ............................................................................................. 97
Class Variables ..................................................................................... 98
Creating Methods ..................................................................................... 99
Defining Methods ............................................................................... 99
The this Keyword ............................................................................... 101
Variable Scope and Method Definitions ............................................ 101
Passing Arguments to Methods .......................................................... 102
Class Methods ................................................................................... 104
Creating Java Applications ...................................................................... 105
Java Applications and Command-Line Arguments ................................. 106
Passing Arguments to Java Programs .................................................. 106
Handling Arguments in Your Java Program ....................................... 106
Summary ................................................................................................ 108
Q&A ...................................................................................................... 109
Day 7 More About Methods 111
Creating Methods with the Same Name, Different Arguments ............... 112
Constructor Methods ............................................................................. 115
Basic Constructors ............................................................................. 116
Calling Another Constructor ............................................................. 117
Overloading Constructors .................................................................. 117
030-4 FM 1/29/96, 8:11 PM11
Teach Yourself JAVA in 21 Days
M T
W T
F S
S
21
xii
P2/V4SQC6 TY Java in 21 Days 030-4 louisa 12.31.95 FM LP#4
Overriding Methods ............................................................................... 119
Creating Methods that Override Existing Methods ............................ 119
Calling the Original Method .................................
本文档为【teach_your_self_java_in_21_days】,请使用软件OFFICE或WPS软件打开。作品中的文字与图均可以修改和编辑,
图片更改请在作品中右键图片并更换,文字修改请直接点击文字进行修改,也可以新增和删除文档中的内容。
该文档来自用户分享,如有侵权行为请发邮件ishare@vip.sina.com联系网站客服,我们会及时删除。
[版权声明] 本站所有资料为用户分享产生,若发现您的权利被侵害,请联系客服邮件isharekefu@iask.cn,我们尽快处理。
本作品所展示的图片、画像、字体、音乐的版权可能需版权方额外授权,请谨慎使用。
网站提供的党政主题相关内容(国旗、国徽、党徽..)目的在于配合国家政策宣传,仅限个人学习分享使用,禁止用于任何广告和商用目的。