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Basics of J2ME. Basics of J2ME. Objectives Understand the different java API’s and how the mobile edition API’s fit in Understand what a mobile configuration and profile is. Basics of J2ME. Quote from Sun

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basics of j2me

Basics of J2ME

CE00213-M Mobile Applications and Systems

basics of j2me1
Basics of J2ME
  • Objectives
    • Understand the different java API’s and how the mobile edition API’s fit in
    • Understand what a mobile configuration and profile is.

CE00213-M Mobile Applications and Systems

basics of j2me2
Basics of J2ME

Quote from Sun

“The Micro Edition of the Java 2 Platform provides an application environment that specifically addresses the needs of commodities in the vast and rapidly growing consumer and embedded space, including mobile phones, pagers, personal digital assistants, set-top boxes, and vehicle telematics systems”

CE00213-M Mobile Applications and Systems

basics of j2me showing various editions
Basics of J2ME showing various editions

Java 2

Enterprise

Edition

(J2EE)

Java 2

Standard

Edition

(J2SE)

MIDP

Profile Level

CDC

CLDC

Configuration Level

Java Virtual Machine

KVM

Java 2 Micro Edition (J2ME)

CE00213-M Mobile Applications and Systems

the java platform
The Java Platform

Source:http://java.sun.com/javame/technology/index.jsp

CE00213-M Mobile Applications and Systems

basics of j2me3
Basics of J2ME

Configurations

“Configurations comprise a virtual machine and a minimal set of class libraries. They provide the base functionality for a particular range of devices that share similar characteristics, such as network connectivity and memory footprint. Currently, there are two J2ME configurations: the Connected Limited Device Configuration (CLDC) and the Connected Device Configuration (CDC). “

CE00213-M Mobile Applications and Systems

basics of j2me4
Basics of J2ME

Configurations

  • Connected Device Configuration (CDC)
    • 512 kilobytes (minimum) memory for running Java
    • 256 kilobytes (minimum) for runtime memory allocation
    • Network connectivity, possibly persistent and high bandwidth
  • Connected, Limited Device Configuration (CLDC)
    • 128 kilobytes memory for running Java
    • 32 kilobytes memory for runtime memory allocation
    • Restricted user interface
    • Low power, typically battery powered
    • Network connectivity, typically wireless, with low bandwidth and intermittent access

CE00213-M Mobile Applications and Systems

cdc packages
CDC Packages

CDC Package Name Description

java.io standard I/O classes & interfaces

java.lang VM classes

java.lang.ref Reference classes

java.lang.reflect Reflection classes & interfaces

java.math Math package

java.net Networking classes & interfaces

java.security Security classes & interfaces

java.security.cert Security certificate classes

java.text Text package

java.util standard utility classes

java..util.jar JAR utility classes

java.util.zip ZIP utility classes

javax.microedition.io CDC generic connection framework

classes and interfaces

CE00213-M Mobile Applications and Systems

cldc packages
CLDC Packages

java.io standard I/O classes & interfaces

java.lang VM classes

java.util standard utility classes

javax.microedition.io CDC generic connection framework

classes and interfaces

CE00213-M Mobile Applications and Systems

the java api s
The Java API’s

J2SE

CDC

CLDC

CE00213-M Mobile Applications and Systems

basics of j2me5
Basics of J2ME

Profiles

“To provide a complete runtime environment for a specific device category a configuration must be combined with a profile, a set of higher-level APIs that further define the application life-cycle model, the user interface, and access to device-specific properties. A profile supports a narrower category of devices within the framework of a chosen configuration. A widely adopted example is to combine CLDC with the Mobile Information Device Profile (MIDP) to provide a complete Java application environment for cell phones and other devices with similar capabilities.”

CE00213-M Mobile Applications and Systems

basics of j2me6
Basics of J2ME

Profiles

  • An extension to a configuration
  • Provides libraries for a developer to write applications for a particular device
    • Mobile Information Device Profile (MIDP) defines API’s for user interface components, input & event handling, persistent storage, networking & timers, allowing for screen & memory limitation of mobile devices

CE00213-M Mobile Applications and Systems

basics of j2me7
Basics of J2ME
  • Java Virtual Machines
    • The JVM (java virtual machine) translates the class files into machine code for platform running the JVM
    • The JVM is also responsible for providing security, allocating& freeing memory & managing threads
    • For CDC the virtual machine is the same J2SE (re-engineered)
    • For CLDC the virtual machine is KVM (Kilobytes virtual machine)
      • 128 Kbytes of memory for running the JVM & CLDC libraries must preserve it’s content when device is switched off (non volatile memory)
      • 32 Kbytes during application runtime for allocation of objects (volatile memory or the “heap”)

CE00213-M Mobile Applications and Systems

mobile information device profile midp
Mobile Information Device Profile (MIDP)
  • MIDP is a set of API’s that allow developers to handle mobile device specific issues
  • MIDP contains packages :
    • javax.microedition.lcdui
      • Has classes to enable developers to construct user interfaces
    • javax.microedition.io
      • Allows networking between midlets and other systems
    • javax.microedition.rms
      • Allows local storage
    • javax.microedition.midlet
      • Defines the midlet lifecycle

CE00213-M Mobile Applications and Systems

mobile information device profile midp1
Mobile Information Device Profile (MIDP)
  • High level API’s
    • Textfields, lists, forms and images for programs such as e-commerce applications & basic user interfaces
  • Low level API’s
    • Incorporate graphics & shapes at precise pixel locations, provides animation for games applications

Download the J2ME wireless toolkit from:

http://java.sun.com/products/j2mewtoolkit/download-2_1.html

CE00213-M Mobile Applications and Systems

configuration for small devices the connected limited device configuration cldc
Configuration for Small Devices - The Connected Limited Device Configuration (CLDC)

Source:http://java.sun.com/javame/technology/index.jsp

CE00213-M Mobile Applications and Systems

references
References
  • Beginning J2ME from Novice to Professional 3rd edition 2005
    • Sing Li, Jonathan Knudsen
    • Publisher Apress
    • ISBN 1-59059-479-7
  • Core J2ME Technology & MIDP 2002
    • Muchow J.W
    • Publisher Sun microsystem
    • ISBN 0-13-066911-3

CE00213-M Mobile Applications and Systems