KONSEP BAHASA PEMOGRAMAN 2: INTRODUCTION TO J2ME

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Arsitektur Jaringan dgn J2ME

Introduction to J2ME - 01

Java 2 Platform Micro Edition (J2ME)

Introduction to J2ME - 02

Java platform for small devices
A subset of J2SE
Released mid June 1999
Target devices:
– Two-way pagers
– Mobile phones, smart phones
– PDAs (inc PocketPCs)
– TVs, VCRs, CD players
Almost every mobile phone support J2ME

J2ME Phones

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3 Java Platforms

Introduction to J2ME - 04

Introduction to J2ME - 05

J2ME Architecture

To increase the flexibility of design, the J2ME consists of two distinct layers: Configurations and Profiles
Configuration
– Defines the minimum Java technology for a broad range of devices with similar capabilities
Profile
– Provides capabilities, on top of configuration, for a specific device type

J2ME Architecture
Two types of J2ME configurations P fil
1. Connected Device Configuration
2. Connected Limited Device Configuration

Introduction to J2ME - 06

CLDC vs CDC
CLDC

160 Kbytes to 512 Kbytes of total memory available
16-bit or 32-bit processor
Low power consumption and often operating with battery power
Connectivity with limited bandwidth.

CDC

2Mbytes or more memory for Java platform
32-bit processor
High bandwidth network connection, most often using TCP/IP

CLDC

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Mobile Information Device Profile (MIDP)

Is a set of APIs that allow developers to control mobile device-specific problems
– i.e. user interfaces, local storage and client application lifecycles etc.

MIDlets minimum requirements
– 96 x 54 pixels mono screen
– two-way wireless network
– input device (i.e. keypad)
– 128 KB for CLDC/MIDP class and another 32 KB for the KVM

Midlets are the most important and popular applications in the J2ME family.

MIDP

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Building J2ME Apps- Tool
We will use Sun Java Wireless Toolkit 2.x for CLDC (The newest version is 2.5.2 in Jan 2008)
which can be downloaded from http://java.sun.com/j2me/download.html

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J2ME Wireless Toolkit Demo

Launch the Wireless Toolkit:
– Start > Programs > Sun Java(TM) Wireless Toolkit 2.5.2 for CLDC

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WTK already includes a set of demo programs ready run

J2ME Wireless Toolkit Demo

Select menu item File > Open Project ...
Select UIDemo and click Open Project.

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The projects can be used as the templates of your applications.

J2ME Wireless Toolkit Demo

Click the Build and then the Run buttons.

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J2ME Wireless Toolkit Demo

The main menu screen is shown up. You can choose a program and select Launch to start the program.

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MIDlet Programming

Any MIDP application must extends MIDlet
This is the MIDP equivalent of an applet, where starting/stopping is under the control of the
environment
Like Java applets, MIDlets have an application life cycle while running on a mobile device.

MIDlet Transition States

Specifically, a MIDlet can be in one of three states as
shown:

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Midlet Skeleton

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import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class MyApp extends MIDlet {
public void startApp() {
// start up code
}
public void pauseApp() {
// we aren't showing any more
}
public void destroyApp(boolean unconditional) {
// clean up
}
}

Two Level API

There are two areas the API which you should be concerned with - the high and low-level API.
High-Level Provides input elements such as,
– text fields, choices, and form
Low-level is for drawing on Canvases and capturing keyed events
All MIDlet applications need to import the necessary midlet and lcdui packages:
– import javax.microedition.midlet.*;
– import javax.microedition.lcdui.*;

Displaying Objects - 01

High-level Screens have a base class called Displayable.
To show something on a MIDP device, you need to obtain the device’s display
– javax.microedition.lcdui.Display class.
This Display class is the one and only display manager for each active MIDlet and provides
information about the device’s display capability.
Subclassed Displayable classes will fill the whole screen

Displaying Objects - 02

To show a Displable object you must use the setCurrent() method on the Display object.
Form mainForm = new Form ("First Program ");
Display display = Display.getDisplay(this);
display.setCurrent (mainForm);

Note that Form is a Displayable subclass.

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Major classes in the lcdui package

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First Example - HelloWorld
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class HelloWorld extends MIDlet {
public HelloWorld() {
}
public void startApp() {
Form form = new Form( "First Program" );
form.append( "Hello World" );
Display.getDisplay(this).setCurrent( form );
}
public void pauseApp() {
}

public void destroyApp( boolean unconditional ) {
}
}

Building the MIDlet using Netbeans 6-01

Run the program Netbeans IDE 6.0, File>New Project
Create new Project, Project Name : FirstProgram
Categories : Mobility, Projects : MIDP Application

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Building the MIDlet using Netbeans 6-02

Project Name : FirstProgram
Uncheck : Create Hello Midlet

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Building the MIDlet using Netbeans 6-03

Device Configuration : CLDC-1.1
Device Profile : MIDP-2.1
Click : Finish

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Building the MIDlet using Netbeans 6-04

File > File…New File
Categories : MIDP
File Types: MIDlet

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Building the MIDlet using Netbeans 6-05

Class Name : HelloWorld
Click : Finish

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Building the MIDlet using Netbeans 6-06

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Building and Run the MIDlet

Click the Run buttons.

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Add another line

To make newline use ‘\n’

Introduction to J2ME -25

Show Image

It supports jpg, png image and save in ‘res’ folder.
Attention about image size, it must be enough to be
displayed in LCD HP.
Adding image, it needs 2 part i.e. :
a. Add import : import java.io.*;
b. Exception :
try { }
catch (IOException e) {}

Example