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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() • destroyApp(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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