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Developing J2ME Applications

Developing J2ME Applications. Mobile and Wireless Networks. J2ME Architecture . Layers consisting of Profiles Configurations Virtual Machines Host Operating System. J2ME Architecture . Configurations They define the minimum Java platform for a set of common devices

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Developing J2ME Applications

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  1. Developing J2ME Applications Mobile and Wireless Networks

  2. J2ME Architecture • Layers consisting of • Profiles • Configurations • Virtual Machines • Host Operating System

  3. J2ME Architecture • Configurations • They define the minimum Java platform for a set of common devices • Support one or more profiles • Horizontal in nature • Defined through Java Community Process (JCP) • Must go through compatibility tests • Profiles • Supplement the configuration to provide capabilities for a specific family of devices or specific industry segment • Provide flexibility while optimizing portability • Often provide UI, event handling, persistence mechanisms, etc. • Defined through JCP • Must go through compatibility tests

  4. J2ME Architecture

  5. J2ME Architecture • J2ME Configurations • Connected Device Configuration (CDC) • Connected Limited Device Configuration (CLD) • Two design • CDC = things you plug into the wall • CLDC = things you hold in your hand • CLDC-Based Profiles • Mobile Information Device Profile (MIDP) • Support for cell phones and pagers

  6. The J2ME Universe Today

  7. Creating J2ME Applications • Identify the devices • Identify the profiles supported by devices • Develop the Application • Using the MID profile, the application will target cell phones and pagers • Write an application that displays the String “Hello, Small World!” • Requires the environment; MIDP reference implementation http://java.sun.com/products/midp/ • Will run in the MIDP emulator

  8. Tour of CLDC/MIDP • Packages • Javax.microedition.io • Javax.microedition.lcdui • Javax.microedition.midlet • Javax.microedtion.rms • Contains user interface widgets • Form, TextField, TextBox, DateField, List, Image, Gauge, Alert, Canvas, Graphics, Display • Event handling classes – Command and CommandListener • Two APIs, high and low • High level for GUI widgets, scrolling, etc. • Low level for graphics and fine-grained UI control

  9. Developing J2ME Wireless Applications • Use ktoolbar to create a project • Configure the Midlet • Build and Run the project • MIDlet class, the application-level class • Abstract, need to define methods • startApp() • pauseApp() • destryApp(boolean unconditional)

  10. Sample Code import javax.microedition.lcdui.*; import javax.microedition.midlet.*; public class HiMIDlet extends MIDlet { private TextBox textbox; public HiMIDlet() { textbox = new TextBox ("", "Hello World!", 20, 0); } public void startApp() { Display.getDisplay(this).setCurrent(textbox); } public void pauseApp() {} public void destroyApp(boolean unconditional) {} }

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