Cracking the Code Wireless Programming with J2ME

Contents
Preface.........................................................................................................viii
Chapter 1: An Overview of J2ME .................................................................1
Introduction ............................................................................................................................................ 1
What J2ME is about......................................................................................................................... 1
What J2ME offers........................................................................................................................... 2
J2ME Virtual Machines .......................................................................................................................... 3
The K Virtual Machine (KVM) ...................................................................................................... 3
The C Virtual Machine (CVM)....................................................................................................... 4
Configurations ........................................................................................................................................ 5
CLDC.............................................................................................................................................. 5
CDC................................................................................................................................................. 7
Profiles.................................................................................................................................................... 8
Mobile Information Device Profile (MIDP)................................................................................... 8
Foundation Profile ........................................................................................................................... 9
Other profiles .................................................................................................................................. 9
Getting Set to Program with J2ME....................................................................................................... 10
Our First J2ME Application.................................................................................................................. 10
RelatedJava Technologies.................................................................................................................... 12
PersonalJava.................................................................................................................................. 12
Java Card....................................................................................................................................... 13
Summary............................................................................................................................................... 15
Chapter 2: Programming Techniques for J2ME........................................16
Constraints of J2ME Targeted Devices................................................................................................ 16
Limited processor speed ................................................................................................................ 16
Limited memory and storage......................................................................................................... 17
Limited networking and bandwidth .............................................................................................. 17
Wide variety of input/output methods .......................................................................................... 18
Size, shape, and weight.................................................................................................................. 20
Rapid changes in the world of small devices................................................................................ 21
Operating systems for mobile devices .......................................................................................... 21
Programming Techniques to Counter the Limitations......................................................................... 22
Do not overload the processor....................................................................................................... 22
Conserve memory to the maximum extent ................................................................................... 22
Pass the load to the server ............................................................................................................. 24
Avoid using string concatenation.................................................................................................. 24
Give the garbage collector light work........................................................................................... 24
Use exceptions sparingly............................................................................................................... 24
Use local variables ......................................................................................................................... 24
Make your suite light..................................................................................................................... 24
Managing with the limited features of J2ME....................................................................................... 25
Plan your application well ............................................................................................................. 25
Use GUI classes optimally and creatively.....................................................................................25
Use the server’s functionality ........................................................................................................25
Use low-level UI APIs in MIDP....................................................................................................25
Use SyncML for data synchronization ..........................................................................................26
Summary ...............................................................................................................................................26
..................................27
Core Packages.......................................................................................................................................27
java.lang package ...........................................................................................................................27
java.io package ...............................................................................................................................27
java.util package .............................................................................................................................28
Brief introduction to commonly used packages............................................................................28
Generic Connection Framework ...........................................................................................................31
Kjava API..............................................................................................................................................33
Brief introduction to commonly used classes .......................................................................................36
Spotlet ............................................................................................................................................36
Graphics.........................................................................................................................................37
Button.............................................................................................................................................37
TextField........................................................................................................................................38
RadioButton and RadioGroup........................................................................................................38
HelpDisplay ...................................................................................................................................39
ScrollTextBox................................................................................................................................39
Database.........................................................................................................................................40
TextBox .........................................................................................................................................41
Installation of CLDC .............................................................................................................................41
Compiling, preverifying, and running applications ......................................................................42
Case Studies ..........................................................................................................................................43
TextField_Spotlet ...........................................................................................................................43
ScrollTextBox_Spotlet...................................................................................................................45
HelpDisplay_Spotlet ......................................................................................................................47
CheckRadio_Spotlet.......................................................................................................................49
HttpCheck_Spotlet .........................................................................................................................52
Server .............................................................................................................................................55
Socket_Check ................................................................................................................................55
Summary ...............................................................................................................................................62
Chapter 4: MIDP-MIDlet Implementation with Case Studies....................63
MIDlets and MIDlet States....................................................................................................................63
MIDlet Suites ........................................................................................................................................64
MIDP API .............................................................................................................................................64
Application Lifecycle Package..............................................................................................................65
User Interface Package ..........................................................................................................................66
Interface CommandListener...........................................................................................................67
Alert Class .....................................................................................................................................68
ChoiceGroup Class.........................................................................................................................69
Command Class.............................................................................................................................70
Display Class .................................................................................................................................71
Form Class.....................................................................................................................................71
Gauge Class ...................................................................................................................................72
Graphics Class ............................................................................................................................... 73
Class List....................................................................................................................................... 75
Class StringItem............................................................................................................................ 76
Class TextField .............................................................................................................................. 76
Class TextBox............................................................................................................................... 77
Class Ticker................................................................................................................................... 78
Persistence Package.............................................................................................................................. 78
Class RecordStore......................................................................................................................... 79
Exceptions in Persistance Package................................................................................................ 82
Installation of MIDP and Running Applications ................................................................................. 82
run.bat............................................................................................................................................ 83
sample.bat...................................................................................................................................... 84
example.jad ................................................................................................................................... 85
J2ME Wireless Toolkit ......................................................................................................................... 85
MIDP for Palm ..................................................................................................................................... 86
Case Studies.......................................................................................................................................... 91
TextFieldCheck............................................................................................................................. 91
LabelUI ......................................................................................................................................... 93
ChoiceGroupUI............................................................................................................................. 95
TickerUI ........................................................................................................................................ 98
MenuCheck ................................................................................................................................... 99
AddressBook............................................................................................................................... 101
TestHTTP.................................................................................................................................... 109
Summary............................................................................................................................................. 111
Chapter 5: Handling and Parsing XML in J2ME ......................................112
Brief Overview of XML ..................................................................................................................... 112
Structure of XML......................................................................................................................... 112
XML Schema.............................................................................................................................. 114
XML Parsing ...................................................................................................................................... 114
XML parsers available for KVM ................................................................................................ 115
Working with kXML........................................................................................................................... 115
org.kxml parser package ............................................................................................................. 116
org.kxml.io package..................................................................................................................... 117
Application ......................................................................................................................................... 117
Structure of the application ......................................................................................................... 117
Functioning of the application..................................................................................................... 117
Application description................................................................................................................ 117
Summary............................................................................................................................................. 124
Chapter 6: Project 1: Online Testing Engine...........................................125
User Interface ..................................................................................................................................... 125
Running the Project............................................................................................................................ 126
How It Works ..................................................................................................................................... 126
TestManager flow chart............................................................................................................... 132
TestManager.java ............................................................................................................................... 134
MainScreen.java................................................................................................................................. 139
QuestionParser.java............................................................................................................................ 155
Books.asp............................................................................................................................................ 159
TestFile.asp .........................................................................................................................................161
Summary .............................................................................................................................................163
Chapter 7: Project 2: Online Ordering System........................................164
User Interface......................................................................................................................................164
Running the Application.....................................................................................................................164
How It Works......................................................................................................................................165
Summary .............................................................................................................................................184
Chapter 8: Project 3: MP3 Player for Pocket PC .....................................185
Working with the CDC Specification .................................................................................................185
Using Emulated Environments............................................................................................................186
The PersonalJava Emulation Environment .................................................................................186
The Pocket PC emulation environment.......................................................................................188
Working without emulation .........................................................................................................189
JavaCheck ...........................................................................................................................................189
Introducing the project........................................................................................................................193
How It Works......................................................................................................................................193
How to Run .........................................................................................................................................200
Working With Wireless Networks ......................................................................................................201
Summary .............................................................................................................................................218
Chapter 9: Project 4 : Peer-to-Peer Search Application.........................219
User Interface......................................................................................................................................219
How It Works......................................................................................................................................220
Source Code ........................................................................................................................................226
Summary .............................................................................................................................................274
Chapter 10: Project 5: Mobile Web Services...........................................275
User Interface......................................................................................................................................275
How to Run .........................................................................................................................................278
How It Works......................................................................................................................................278
MainClass.java .............................................................................................................................291
DataParser.java............................................................................................................................294
Weather.java ................................................................................................................................305
News.java.....................................................................................................................................311
MoviesList.java ............................................................................................................................319
Summary .............................................................................................................................................328
Chapter 11: Project 6: Target Practice Game..........................................329
User Interface......................................................................................................................................329
How It Works......................................................................................................................................330
Source Code ........................................................................................................................................334
Code explanation.........................................................................................................................339
MainClass.java .............................................................................................................................340
Summary .............................................................................................................................................354
Chapter 12: Converting J2SE Applications to J2ME ..............................355
Issues Involved in Conversion ............................................................................................................355
Differences in Java language support and virtual machines.......................................................355
Differences in the hardware......................................................................................................... 356
Problems due to device variety ................................................................................................... 356
Differences in the application models......................................................................................... 357
Differences in APIs...................................................................................................................... 357
What Conversion Entails .................................................................................................................... 358
Modifying the application design, if necessary .......................................................................... 358
Reducing the GUI ........................................................................................................................ 358
Removing unnecessary or impossible functionality................................................................... 359
Optimizing the use of resources .................................................................................................. 359
Using JavaCheck ................................................................................................................................ 359
An Example of Conversion................................................................................................................. 361
Analyzing the design ................................................................................................................... 361
Reducing the GUI ........................................................................................................................ 362
Is some functionality unnecessary or impossible? ..................................................................... 363
Listing the items consuming resources ....................................................................................... 364
Testing the application................................................................................................................. 365
Summary............................................................................................................................................. 365
Appendix A: About the CD-ROM ..............................................................366
System Requirements......................................................................................................................... 366
What’s on the CD............................................................................................................................... 366
Source code................................................................................................................................. 366
Applications ................................................................................................................................ 367
E-Book ........................................................................................................................................ 367
Troubleshooting.................................................................................................................................. 367
Index ...........................................................................................................369
End User License Agreement...................................................................377
Sun Microsystems, Inc. Binary Code License Agreement.....................379
License Agreement: Forte for Java, Release 2.0 Community Edition
for All Platforms ......................................................................................382

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