Developing an Application with J2ME Technology

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Developing an Application with J2ME Technology

• Scott Palmer, Nat Panchee, Judy Sullivan,
• Karen Thabet, Sten Westgard

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Java -One size does not fit all
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Java Technology - Editions
Memory footprint decreases
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J2ME - Characteristics

• J2ME maintains qualities of Java Technology
• Consistency across products
• Portability of code

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J2ME - Characteristics

• Run anywhere, anytime and on any device
• Safe network delivery
• Upward scalability with J2SE and J2EE technology
• OOP base language

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What is a Configuration?

• Specifies Java Programming language features
  supported
• Specifies the JVM features supported
• Specifies the basic Java libraries and APIs
  supported

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J2ME Configurations

• Connected Device Configuration (CDC)
• Connected Limited Device Configuration (CLDC)
• Purpose
• CDC High end consumer devices
• CDLC Low end consumer devices

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Java2 Micro Edition - Architecture
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CDC

• 32 bit processor
• gt.5MB (ROMRAM)
• JVM support
• High bandwidth network connectivity
• Devices include
• Communicators
• Next Generation Smart Phones
• Home Appliances
• Car Navigation Systems

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CLDC

• 16-32 bit processor
• gt160-512kB (ROMRAM)
• KVM support
• Limited power/battery, network, GUI, Java class
  libraries
• Devices include
• Cell phones
• Personal Digital Assistants
• Pagers

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CLDC Expert Group

• America Online
• Bull
• Ericsson
• Fujitsu
• Matsushita
• Mitsubishi
• Motorola
• Nokia
• NTT DoCoMo

• Oracle
• Palm Computing
• RIM
• Samsung
• Sharp
• Siemens
• Sony
• SunMicrosystems
• Symbian

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CLDC Packages

• CLDC packages
• java.lang
• java.io
• java.util
• javax.microedition.io

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CLDC

• CLDC limitations
• No Floating-point Support
• No Finalization
• Error Handling Limitations
• Limited Internationalization Support

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MIDP Mobile Information Device Profile

• MIDP CLDC
• Part of J2ME Runtime Environment

• MIDP addresses
• User Interface
• Persistent storage
• Networking
• Application model

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MIDP Packages

• MIDP Packages
• javax.micoredition.io
• javax.microedition.midlet
• javax.microedition.lcdui
• javax.microedition.rms

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What is a MIDlet?

• MIDP Application MIDlet
• MIDlet is similar to applet.
• MIDlet Structure
• startApp()
• pauseApp()
• destroyApp(boolean unconditional)

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MIDlets Life Cycle
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Hello Midlet

• import javax.microedition.midlet.
• import javax.microedition.lcdui.
• public class HelloMidlet extends MIDlet
• private Display display
• TextBox box null
• public HelloMidlet()
• public void startApp()
• display display.getDisplay(this)
• box new TextBox("Midlet Example", "Hello
  CS616", 20, 0)
• display.setCurrent(box)

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Hello Midlet
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J2ME Wireless Toolkit
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Developer Opportunities

• Mobile Internet services
• Value added services
• Business to business apps

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A Wireless Safe Home
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Java Enabled Device Future

• In 2002, Nokia will deliver more than 50 million
  Java enable phones more than 100 million
  deliveries by end of 2003.

Pekka Ala-Pietila, Nokia President, JavaOne, 2001