Java ME is a widely used platform for developing applications for mobile devices, with over 6 billion Java-enabled devices in use. It is a subset of the Java SE platform tailored for devices with limited hardware capabilities. Java ME applications are built using configurations like CLDC and profiles like MIDP, and may use Java Specification Requests (JSRs) that define APIs for things like location, graphics, and web services. Popular integrated development environments for Java ME include NetBeans and Eclipse, which are used to compile, package and deploy applications to emulator and real devices.

1. Java ME
Andreas Jakl
Senior Technical Consultant
Forum Nokia
13 April, 2010

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Java?
• In numbers:
– > 6 Billion Java-enabled devices
– 2.6 Billion Java-enabled phones
(8 out of 10 shipped in 2008)
– 3.5 Billion Java Cards
– 20 Million Java set-top boxes
– 800 Million Java desktops
– 180 Operators deploying Java content
– 6 Million developers

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MSA … Mobile Service Architecture (JSRs 248 and 249)
Editions
JTWI … Java Technology for the Wireless Industry, JSR 185
MIDP … Mobile Information Device Profile
CDC … Connected Device Configuration
CLDC … Connected Limited Device Configuration
Servers & Servers & High-end Mobile phones & Smart
enterprise personal PDAs, TV set-top entry-level PDAs cards
computers computers boxes, embedde
d devices
Optional
Packages
Optional
Packages Optional
Packages
Personal Profile Optional
Packages
Java 2 Personal
Platform, E Java 2 Basis
MSA
nterprise Platform, St Profile
Edition andard JTWI
(J2EE) Edition Foundation
MIDP
(J2SE) Profile
CDC CLDC Java Card
Java Platform, Micro Edition (Java ME)

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Java SE vs. Java ME
• Java ME is mainly a subset of J2SE
– But different UI- and event handling functionality
– Less utility classes
(only Vector and Hashtable, no LinkedLists, …)
• Code runs on both platforms?
– general algorithms: yes
– But the whole application needs porting

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Targets
+ RIM / Blackberry
+ SonyEricsson
+ Motorola

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Basic Terms – Configuration
• Defines Java platform for different device classes
– CLDC
• Limited UI Currently used in
• Low computing power,
most phones:
CLDC 1.1
• Limited connectivity
– CDC
• High bandwidth network connection
• larger memory requirements

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Basic Terms – Profile
• Extension and more detailed specification for a configuration
– Contains 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)
– Currently used: MIDP 2.1

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Tornado Mania! 3D
Basic Terms – JSR
(Digital Chocolate)
• Java Specification Request (JSR)
RealReplay
– Describe specifications and technologies (Mopius)
– Mobile space: APIs, standards
• Examples:
– JSR 82: Bluetooth APIs
– JSR 179: Location API
– JSR 184: Mobile 3D API
– JSR 226: Scalable 2D Vector Graphics API

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What JSRs could be required?
• A mapping application could require:
– JSR 226 (Vector Graphics)
• Map visualization
– JSR 179 (Location)
• Where am I?
– JSR 172 (Web Services)
• Requesting data
– JSR 75 (File and PIM) Google Maps Mobile
© Google
• Map an address

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What does my phone support?
http://www.forum.nokia.com/devices/

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Development – NetBeans IDE
• Fully integrated solution
– Integrates all aspects of mobile
development
– Visual UI Designer
– Game Builder
– Localization, Preprocessing
– Web access
– Automated deployment
– Comes with generic emulator
• Maintained by Oracle (Sun)
– http://www.netbeans.org/
NetBeans (+ Java ME module)

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Development – Eclipse IDE
• Mobile Tools for Java (MTJ)
– Targets Java ME development
– Supports MIDlets
– Adds project type and Java ME perspective to Eclipse
– Templates for common projects (games, etc.)
– Localization, Preprocessing
– Creates .jad/.jar packages
– Originally based on EclipseME plug-in
• Pulsar
– Combined tools set – includes Eclipse, MTJ and other tools
– http://eclipse.org/pulsar/

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SDKs
• Device vendor specific SDKs
– Simulate target more accurately
– Support proprietary APIs
– Include device skins
• Generic SDK from Sun
– Fine enough for initial development
– http://java.sun.com/javame/downloads/sdk30.jsp

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Deployment Process
.jar/.jad-file
(MIDlet Suite)
Packaging
Compile &
Preverify
Source code
(.java)

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Future of Java ME
• Roadmap
– Nokia makes its Java ME implementation open source
• Contribution to Symbian Foundation
– Next version: Java Runtime 2.0 (JRT)
• Faster startup
• Easier installation
• Beta: http://betalabs.nokia.com/apps/nokia-java-runtime-20-for-s60
– Future
• Migration to Qt based UI ongoing
• Hardware acceleration, haptics, etc.
– http://blogs.forum.nokia.com/blog/java-runtime-for-s60-blog

16. Thank You.