This is an introduction to Java mobile programming

1. Java Mobile Programming
Africa Nazarene University,
Meru Campus
May Trimester, 2013
Raphael Wanjiku,
Computer Science Department

2. Introduction to Java Micro Edition (J2ME)
This refers to Java for small devices. These range from pagers, mobile phones and PDAs.
J2ME is classified into:
a) Configurations: designed for specific kind of devices based on processing power and
memory. Device manufacturers are responsible for porting configurations into different
devices. Configurations differ due to the device memory and processing power.
Currently there are two configurations:
i) Connected Device configuration (CDC) - has 512 ROM and 256 RAM.
It is suited for set boxes, car-navigation systems and high-end PDAs.
ii) Connected Limited Device Configuration (CLDC) - this includes mobile
phones, PDAs, pagers and devices of similar size. These devices have limited
memory, limited CPU power, limited display size, limited input and limited battery
life. It is based on a small JVM (Java Virtual Machine) called KVM.
b) Profiles: layered on the configurations and provide additional APIs which enable
development of applications of similar device family e.g. user interface, persistent storage
and all that is required to run applications for the device.
Mobile Information Device Profile (MIDP)
This caters for a device with the following characteristics:
i) A minimum memory of 256 Kb ROM
ii) A minimum of 256 Kb Java runtime available memory
iii) A screen of at least 96*54 pixels.
iv) Some capacity for input, either keypad, keyboard or touch screen.

3. Advantages of MIDP
a) Portability - An application written using MIDP API can run on any MIDP device.
b) Security – Java is well known for its secure applets. A vital part of the bytecode
verification must be performed off the MIDP device. Secondly, CLDC does not allow
application-defined class loaders.
c) Additional APIs: these refer to anything else e.g. libraries that are required to enhance
device capabilities, but for particular utility on the device. E.g. Bluetooth API