Writing Your First MIDlet Running JAVA on a Cell Phone Jon A. Batcheller January 27, 2004

Overview The MID The CLDC & MIDP API Developing Code Emulation Deployment

MID – Mobile Information Device Cell Phones, Palms, Blackberry…. Pocket Fisherman? JAVA = one program, multi-platforms “similar platforms” - WORA

MIDP Reduced JVM J2ME – Java 2 Mobile Edition CLDC – Connected Limited Device Configuration CDC – Connected Device Configuration – full JVM imp. MIDP – Mobile Information Device Profile Personal Java, Embedded Java, JavaPhone

MIDP MID MID Native (SYMBIAN OS) CLDC MIDP Native Apps JAVA MIDP Apps

CLDC 128K to 512K total memory Limited Power Limited Connectivity (9600bps) Reduced UI Cell Phones, Pagers, PDA’s

MIDP API and virtual machine to device domain java.lang java.util java.io javax.microedition.io javax.microedition.lcdui javax.microedition.rms javax.microedition.midlet

Development Tools Sun Micro – J2ME Wireless Toolkit MIDP Borland & Sun Forte Nokia – Standalone & JBuilder attachment Need environment to compile (library), verify, package, emulate, and finally deploy

Writing our first MIDlet Application written for the MIDP Profile Must derive from javax.microedition.midlet.MIDlet Must implement startApp(), pauseApp() and destroyApp() Typically also implement a default constructor and a commandAction() from the CommandListener interface

MIDlet Lifecycle

HelloMIDlet.java Extends MIDlet Implements startApp, pauseApp, destroyApp Like an Applet, need something and somewhere to display Display.vs. Displayable Foreground.vs. Background Current Displayable

HelloMIDlet.java Extends MIDlet Implements startApp, pauseApp, destroyApp Like an Applet, need something and somewhere to display Display.vs. Displayable Foreground.vs. Background Current Displayable

Display Object Displayable current = Display.getDisplay(this).getCurrent(); Returns current Displayable Typically in startApp(), look for current Displayable, if null, create own and set it as current.

HelloScreen Displayable current = Display.getDisplay(this).getCurrent(); Returns current Displayable Typically in startApp(), look for current Displayable, if null, create own and set it as current.

HelloMIDlet.java Compile Note project library Package Emulate Deploy Test

Package JAD Versions – JAD, CLDC, MIDP Multiple MIDlets – Suites Other Classes Other Files JAR

JAD – Java Application Descriptor Usually a link on a WAP site Info on the MIDlet Most Important – URL of the JAR Downloaded to MID then user queried to download JAR

JAD – Java Application Descriptor MIDlet-Name: HelloWorld MIDlet-Version: MIDlet-Vendor: Solidware, Inc MicroEdition-Profile: MIDP-1.0 MicroEdition-Configuration: CLDC-1.0 MIDlet-Jar-URL: HelloWorld.jar MIDlet-Jar-Size: 1592 MIDlet-1: HelloWorldApp,, HelloWorldApp

Deploy JAD first JAR on request Methods –IR –BlueTooth – –WEB – “Over the Air”

Emulate Emulators – part of toolkits – Sun or Phone articles/emulators Debugging Environment Interesting Behaviors

Test –Download jad –Queries user if new or different version –Download jar –Execute Application Review Application details

PropExample.java Review Code Emulators Test

javax.microedition.lcdui MIDP Low & High-level APIs Displayable CanvasScreen AlertFormListTextBox

javax.microedition.lcdui Contents of Form and Alert Screens Item ChoiceGroupDateFieldGaugeImageItemStringItemTextField

UiDemo.java Look and Feel Bejeweled

javax.microedition.io CLDC – HTTP protocol! Connection object Content, Datagram, HTTP, Stream Normal Stream I/O –Open with URL –Get input/output streams –Read/Write –Close

javax.microedition.io HttpExample.java Log & Server2.java

javax.microedition.rms Named record store Access to byte array records Add, Get, Store Stock Ticker

Writing Your First MIDlet Running JAVA on a Cell Phone And the discussion continues at McMenamin’s Greenway Pub, SW Scholls Ferry Road North on 217 next exit, then West