This document provides an introduction to Java ME, the Java platform tailored for mobile devices, detailing its configurations like CLDC and CDC, and profiles such as MIDP. It covers the distinctions between Java ME and J2SE, the significance of application programming interfaces, and various Java-enabled devices. Additionally, it discusses the development environment, tools available for building Java ME applications, and challenges related to fragmentation and memory constraints in mobile programming.

1. Java™ Platform, Micro EditionPart 1 – Introduction to Java ME, CLDC and MIDPv3.0b – 25 April 20091Andreas Jakl, 2009

2. DisclaimerThese slides are provided free of charge at http://www.symbianresources.com and are used during Java ME courses at the University of Applied Sciences in Hagenberg, Austria at the Mobile Computing department ( http://www.fh-ooe.at/mc )Respecting the copyright laws, you are allowed to use them:for your own, personal, non-commercial usein the academic environmentIn all other cases (e.g. for commercial training), please contact andreas.jakl@fh-hagenberg.atThe correctness of the contents of these materials cannot be guaranteed. Andreas Jakl is not liable for incorrect information or damage that may arise from using the materials.This document contains copyright materials which are proprietary to Sun or various mobile device manufacturers, including Nokia, SonyEricsson and Motorola. Sun, Sun Microsystems, the Sun Logo and the Java™ Platform, Micro Edition are trademarks or registered trademarks of Sun Microsystems, Inc. in the United States and other countries. Andreas Jakl, 20092

3. About me: Andreas JaklAssistant Professor at the University ofApplied Sciences, Hagenberg since 2006Teaching:Introduction to Software Development (1st semester BSc)Java ME (2nd semester BSc)Qt / Symbian OS (3rd semester BSc)Bachelor Thesis Seminar (5th semester BSc)Mobile Operating Systems (1st semester MSc)Interaction Technology (2nd semester MSc)Andreas Jakl, 20083

4. About me: Andreas JaklExperience:Forum Nokia Champion (2007, 2008, 2009)Founded company “Mopius” in 2004Internship, Master‘s Thesis and summer jobs at Siemens / BenQ Mobile (Munich, R&D)Studied Bachelor & Master of Digital Media in Hagenberg / Austria (2001 – 06)Contact:Office A.005a (FH1, lower floor)andreas.jakl@fh-hagenberg.atAndreas Jakl, 20094

5. Java PlatformWhat is it all about?5Andreas Jakl, 2009

6. The Java Platform, Part 1 / 3Javaprogramming languageCompared to C++:No pointersAutomatic garbage collectionInterfaces instead of multiple inheritanceComes with an extensive libraryAndreas Jakl, 20096

7. The Java Platform, Part 2 / 3Virtual Machine (JVM)Executes compiled Java bytecode (.class)Available for many systemsControls the code (security)Often used for mobile phones: Kilobyte Virtual Machine (KVM)Memory footprint starting at only 60 kB (+)Now being replaced by Hotspot JVMs.Andreas Jakl, 20097

8. The Java Platform, Part 3 / 3ApplicationProgramming Interfaces (APIs)Manifoldlibrariese.g. UI, network, 3D, locationbasedservices, etc.Andreas Jakl, 20098

9. Java?In numbers:> 6 Billion Java-enabled devices2.6 Billion Java-enabled phones(8 out of 10 shipped in 2008)3.5 Billion Java Cards20 Million Java set-top boxes800 Million Java desktops180 Operators deploying Java content6 Million developersAndreas Jakl, 20099

10. Java EditionsAndreas Jakl, 200910MSA … Mobile Service Architecture (JSRs 248 and 249)JTWI … Java Technology for the Wireless Industry, JSR 185MIDP … Mobile Information Device ProfileCDC … Connected Device ConfigurationCLDC … Connected Limited Device ConfigurationServers & enterprise computersServers & personal computersHigh-end PDAs, TV set-top boxes, embedded devicesMobile phones & entry-level PDAsSmart cardsOptional PackagesOptional PackagesJava 2 Platform, Enterprise Edition (J2EE)Optional PackagesJava 2 Platform, Standard Edition (J2SE)Personal ProfileOptional PackagesPersonal Basis ProfileMSAJTWIFoundation ProfileMIDPCDCCLDCJava CardJava Platform, Micro Edition (Java ME)

11. Java MEGoing MobileAndreas Jakl, 200911

12. Differences J2SE / Java ME (MIDP)Java ME is mainly a subset of J2SEBut different UI- and event handling functionalityLess utility classes (only Vector and Hashtable, no LinkedLists, …)Code runs on both platforms? general algorithms: yesBut the whole application needs portingAndreas Jakl, 200912

13. Name: J2ME or Java ME?Official name:Java Platform, Micro Edition (Java ME)Former name:J2MEAndreas Jakl, 200913

14. ConfigurationDefines Java Platform for different device classes:CLDCLimited user interfaceLow computing power (usually with a battery)Network with low bandwidthCDCNetwork connection with high bandwidth, possibly persistentLarger memory requirementsAndreas Jakl, 200914

15. CDCEquivalent to Java SE 1.4.2 when combined with:Foundation Profile (FP)Extends CDC to Java SE 1.4.2, without graphics and UIPersonal Basis Profile (PBP)Lightweight GUI support (AWT subset)Personal Profile (PP)Extends PBP with AWT components and Appled supportFoundation for Java-based platforms:(few) smartphones, Blu-Ray, Set-top boxes, etc.Andreas Jakl, 200915

16. CLDCCurrentlyavailable in twoversions:1.0In devicesuntil ~ 2005 (atthelatest)1.1CurrentstandardSupports floatingpoint(but mostly in software slow)Important e.g. for GPS coordinatehandling!Usedfor:Phones (!)Consumer andentertainmentdevicesEmbedded platforms, controllers, sensorsSun SPOTsAndreas Jakl, 200916

17. ProfilesExtension and more detailed specification for a configurationContains APIs for UI, event handling, data storage, networks, timers, …Minimum requirements for devices (screen size, input possibilities, ...)For mobile phones:Mobile Information Device Profile (MIDP)Andreas Jakl, 200917

18. Profiles – Major DifferencesMIDP 1.0Hardly any sound support, limited graphicsOnly HTTP, no Sockets Many vendor-specific extensions (bad!)MIDP 2.0Game APIBetter network and multimedia supportMIDP 2.1Tries to improve fragmentation problems (different version for every phone…)Stricter specifications for packagesMIDP 3.0 (JSR 271)Multiple MIDlets can run concurrently or in the background, auto-launchMore detailed specificationsMore possibilities for the UI, support of secondary displaysAndreas Jakl, 200918

19. Sample Architectureof a PhoneAndreas Jakl, 200919Profile: MIDP 2.0Configuration: CLDC 1.1Virtual Machine: HotSpotOperating System

20. Java ME – ExamplesMotorolaMOTORAZR V3CLDC 1.0MIDP 2.0Andreas Jakl, 200920

21. Java ME – ExamplesNokia N70CLDC 1.1MIDP 2.0Andreas Jakl, 200921

22. Java ME – ExamplesSonyEricsson P990iCLDC 1.1MIDP 2.0CDC 1.0Personal ProfileAndreas Jakl, 200922

23. Java ME – ExamplesNokia N86 8MPCLDC 1.1MIDP 2.1MSA (Subset)Andreas Jakl, 200923

24. Java ME – Examples Andreas Jakl, 200924Amazon Kindle 2CDC

25. JSRs (Java Specification Requests)JSR = CLDC, MIDP or libraries for additional featuresDefined through:Java Community Process (JCP)Examples:JSR 82: Bluetooth APIsJSR 179: Location APIJSR 184: Mobile 3D APIJSR 226: Scalable 2D Vector Graphics APIAndreas Jakl, 200925

26. JSRs – How Many?Sample: supported JSRs of Nokia N86 8MPAndreas Jakl, 200926

27. JSRs – Games?A racing game could require:JSR 184 (3D Graphics)3D worldJSR 135 (Mobile Media)SoundJSR 82 (Bluetooth)P2P GamingJSR 180 (SIP)P2P over the networkJSR 229 (Payment)New forms of paymentAndreas Jakl, 200927Asphalt 4: Elite Racing HD© Gameloft

28. JSRs – Mapping Applications?A mapping application could require:JSR 226 (Vector Graphics)Map visualizationJSR 179 (Location)Where am I?JSR 172 (Web Services)Requesting dataJSR 75 (File and PIM)Map an addressJSR 238 (Internationalization)Global softwareAndreas Jakl, 200928Google Maps Mobile© Google

29. „Write Once, Run Anywhere™“ ?Problems:Different screen sizesBugs in manufacturers implementations (!)Different hardware performanceWhich JSRs are supported? Bluetooth? SVG? Web services?…MIDP 2.0 isn’t strict enough:Different key codes for every manufacturer (softkeys, ...)Are socket connections available?Which sound files are playable? Supported image formats?Is double buffering supported?Andreas Jakl, 200929

30. JTWI – Fragmentation Solution?Java Technology for the Wireless Industry (JSR 185)First try of defining full API stack to reduce fragmentationClarification of component JSR specificationsHowever: too small, too few APIs includedBad licensing politics FailedAndreas Jakl, 200930

31. Mobile Service Architecture(MSA, JSR 248)Goal?“Umbrella” specification, replace JTWIDefine a unified platform for majority of handsetsSpec leds: Nokia, Vodafone. Others heavily involvedDevices started to ship in 2007With at least subset of MSAAndreas Jakl, 200931

32. Features in MSA for CLDCAndreas Jakl, 200932Application EnvironmentVirtual MachineJSR 185JTWIJSR 118MIDP 2.0JSR 238I18NJSR 139CLDC 1.1Conditional APIsJTWI APIs

33. MIDP 3.0High-level goalsAdd much-requested functionality over MIDP 2Rework security model to support CLDC and CDCEnables support of MIDP 3 on CDCClarify spec and increase implementation consistencyAndreas Jakl, 200933

34. MIDP 3.0 Functional EnhancementsConcurrency (Multiple MIDlets at the same time)Shared libraries (LIBlets)Auto-start MIDletsIdle screen MIDletsInter-MIDlet communicationRecord store interchange formatUser Interface improvements... Andreas Jakl, 200934

35. Mobile Service Architecture v2Dynamic EnvironmentDownload new APIs to the handsetPlace custom middleware on handsetNext revision of MSA 248Supports both CLDC and CDCBuilds upon and requires MIDP 3.0Adds multi-tasking and on-device service frameworkAdds competitive user interface toolkitAdds device segments: entry, standard, advancedNo final release date yetAndreas Jakl, 200935

36. JavaFXJavaFX(http://javafx.com – integrated in NetBeans 6.5+)New UI libraries (graphics, media, web services)Consistent experience across mobile, desktop, browser, TV, etcPlus: use any Java library in JavaFXIntegrated with Java RuntimeJavaFX ScriptSimple declarative language, easier to learne.g., for artists to change sprite animation, without needing software developerAdvantage to JavaScript / ActionScript: integration with Java – reuse any Java libraryAndreas Jakl, 200936

37. JavaFX MobileRuns on Java ME (plus Android)Mobile content with same tools as Java FXAvailability?JavaFX Mobile Runtime needs to be pre-installed on the phoneNo phones released yetCurrently endorsed by: SonyEricsson, LGAndreas Jakl, 200937

38. Blu-Ray Disc Java: BD-JBased on Java ME Personal Basis Profile & earlier Java TV specGUI environment suitable for consumer electronics (no keyboard / mouse)Strong media supportApplications?Dynamic menu systemsDownloading additional content (subtitles, movie previews, etc.)Games and other bonus materialAndreas Jakl, 200938

39. Java ME – ApplicationsInternalsAndreas Jakl, 200939

40. Runtime environment (KVM)IDECode  ApplicationAndreas Jakl, 200940Source code (.java)Runtime verificationInterpreterCompile(javac).jar-file(MIDlet Suite).class-filesPackagingPreverification.class-files

41. PreverificationVerification: check the integrity of the byte code at runtime Too much for mobile devices, therefore: pre-verification at compile time:Takes care of resource demanding checksSimplifies runtime verificationAdds additional attributes to the .class file (5 – 15% increase in size)Andreas Jakl, 200941

42. MIDlet SuiteAndreas Jakl, 200942MIDlet Suite (.jar-Archiv):- Defines access rights- Possibility to share data (Record Stores)- Shared static variablesMIDlet 1MIDlet 3MIDlet 2

43. MIDlet-SuiteAndreas Jakl, 200943.jar-archive(MIDlet Suite)Preverified .class-file(s)Resources (icons, graphics – optional).jadfile(Applicationdescriptor, optional)ManifestInformation about .jar

44. ManifestText file “MANIFEST.MF”Contains meta informationAndreas Jakl, 200944Manifest-Version: 1.0MIDlet-Name: RealReplayMIDlet-Description: RealReplayMIDlet-Vendor: MopiusMIDlet-Info-URL: http://www.mopius.com/MIDlet-Version: 0.96.20MIDlet-Icon: /res/icon.pngMIDlet-1: RealReplay,/res/icon.png,com.mopius.realreplay.RealReplayMIDletMicroEdition-Profile: MIDP-2.0MicroEdition-Configuration: CLDC-1.1

45. ApplicationDescriptor (.jad)Information about .jarcontentsAllowsto check compatibilitybeforedownloading .jarAndreas Jakl, 200945MIDlet-Name: RealReplayMIDlet-Description: RealReplayMIDlet-Vendor: MopiusMIDlet-Info-URL: http://www.mopius.com/MIDlet-Version: 0.96.20MIDlet-Icon: /res/icon.pngMIDlet-1: RealReplay,/res/icon.png,com.mopius.realreplay.RealReplayMIDletMicroEdition-Profile: MIDP-2.0MicroEdition-Configuration: CLDC-1.1MIDlet-Jar-Size: 114185MIDlet-Jar-URL: http://realreplay.mopius.com/files/realreplay.jarAdd.

46. SigningAccess to some telephone functionality (e.g. socket connections, SMS) restricted: warning is displayed every timeSolution:Sign the checksum of .jar in .jad-file with an own key (certificate)Own certificate is signed with root certificate of a trusted certificate authorityAndreas Jakl, 200946

47. Why OTA for Deployment?Some phones (Samsung, Sagem, BREW,...) do not support installing MIDlets through the PC or BluetoothOnly alternative:Download directly through mobile phone  Over-the-Air (OTA) deliveryAndreas Jakl, 200947

48. Over-the-AirAndreas Jakl, 200948HTTPWeb ServerMobile DeviceAMS (Application Management Software)JAD-ServerJAR-ServerNotification ServerGET /midlet.jadGET /midlet.jarPOST /install-notify (900 Success)200 OK200 OK200 OK

49. Optimization – ObfuscationOriginal intention:Make reverse engineering more difficultCode more difficult to read after de-compilationRenames classes to “a.class, b.class, …”Removes unused methods, variables, classes Significant size reductionOver-the-Air = expensive!MIDlet size restrictions in many phonesImproves speed (less code to load / parse)Andreas Jakl, 200949

50. ObfuscationOriginal archive79,2 kBObfuscated42,9 kB = 45% smaller!Andreas Jakl, 200950

51. Developing for JavaMEHighest priority: memory usage and speed often very few classes, object orientation reduced to a minimum, frequent use of static variablesBut: today’s phones have got more memoryAndreas Jakl, 200951Example:Winter Sportsfrom DigimentOpen Source (GPL)

52. ToolsHow to develop:52Andreas Jakl, 2009

53. IDEs: Sun NetBeansNetBeans (+ Mobility Pack)Andreas Jakl, 200953

54. IDEs: NetBeansVery good integration for mobile projects:LocalisationConditional compilationPackagingUI-Designer, game builder, …Relatively high system requirementsAndreas Jakl, 200954

55. IDEs: EclipseEclipse + Plugin: EclipseME / MTJ (officialplug-in)Andreas Jakl, 200955Is integrated in

56. IDEs: EclipseVery good IDEHelps a lot with programming errorsME integration through Eclipse ME is averageFew Java ME specific tools / support – just pure JavaAndreas Jakl, 200956

57. EmulatorsSun Java Wireless Toolkit for CLDC (2.5.2 / 3.0 EA)Tools for compiling, packaging and executingEmulator:DebuggingError handlingText output through consoleAllows performance analysisSimulates internet access and GPSDownload:http://java.sun.com/javame/downloads/index.jspAndreas Jakl, 200957

58. Sun WTKAndreas Jakl, 200958Sample applicationofNetBeans in the WTK emulator

59. Manufacturer-Specific EmulatorsDifferent Java ME implementations Every device manufacturer has its own emulator:Nokia:www.forum.nokia.com/Resources_and_Information/Tools/IDEs/Sony Ericsson SDK for the Java ME Platformdeveloper.sonyericsson.com/site/global/docstools/java/p_java.jspSamsunginnovator.samsungmobile.com/Motoroladeveloper.motorola.com/docstools/sdks/Andreas Jakl, 200959

60. J2ME PolishTools suite to address Java ME shortcomings:Own UI classes for custom, graphical UIBuild system, creates adapted version for specific handsetsAllows porting Java ME to AndroidLicensing:Free for GPL products1 commercial app: €990Unlimited commercial apps: €14,990http://www.j2mepolish.org/Andreas Jakl, 200960

61. Event-HandlingCommandsAndreas Jakl, 200961

62. Events – The Big PictureAndreas Jakl, 2009* Requires registering the MIDlet62

63. ListenerImplement the Listener-Interface to get informed:CommandListener: commandAction()Notification when e.g. a menu item has been selectedItemCommandListener: commandAction()Used for events for individual itemsItemStateListener: itemStateChanged()When an UI element has been changedAndreas Jakl, 200963

64. Recap: Interfaces?Interface: implemented by 1+ classesDefines abstract methods and constantsBut doesn’t contain the implementation!Implementing class has to override all defined methodsImportant for generic development!Caller does not need to know exact class type and name, but can work with the interface typeMore information at: http://en.wikipedia.org/wiki/Interface_(Java)Andreas Jakl, 200964Interface definition:Interface implementation:publicinterfacePredator {booleanchasePrey(Prey p);voideatPrey(Prey p);}publicclassCatimplementsPredator { publicbooleanchasePrey(Prey p) {// programmingtochaseprey p (specificallyfor a cat) }publicvoideatPrey (Prey p) {// programmingtoeatprey p (specificallyfor a cat) }}

65. CommandsCommand = semantic information about an action ( how can an action be executed?)But no actual implementation of the action!Contains:Short labelLong label (optional)TypePriorityAndreas Jakl, 2009One of them will be displayed on the screen / in the menu, depending on the available space“Intention” of the command – e.g. for special placement on the deviceFor the order of commands, if more are mapped to the same softkey. The lower the priority, the more important it is.65

66. Command-TypesAndreas Jakl, 200966

67. ExitClass HelloWorldMIDlet:… implements CommandListenerDefine new command (member variable):private Command cmdExit;Create it in the constructor:cmdExit = new Command(“Exit”, Command.EXIT, 1);frmMain.addCommand(cmdExit);frmMain.setCommandListener(this);Andreas Jakl, 2009Implementation e.g. like in the “Hello World”-Exercise67

68. Command HandlingMethod defined in the base class CommandListener:public void commandAction (Command c, Displayable d){if (c == cmdExit) {destroyApp(true);notifyDestroyed(); }}Andreas Jakl, 2009true: forces shutdown, you have to free resources!false:shtudown can be prevented by the MIDlet if necessary.... mainly important if the framework wants / has to close down the app.Inform the app. manager that ourMIDlet wants to be shut down. 68

69. Exit SoftkeyAndreas Jakl, 200969

70. 2 Softkeys, 3 Commands?Commands in themenu – placementdepends on thephone:Andreas Jakl, 2009NokiaSeries 40WTK 2.5Nokia S6070

71. Thanks for your attentionThat’s it!Andreas Jakl, 200971