Specifications

White Paper V800-Vodafone V802SE
44 August 2004
Java
J2ME™
Originally developed by Sun in 1991, Java is a pro-
gramming language used to develop applications -
utility programs, games, plug-ins etc. - for different
hardware and software platforms. Users of Java-
enabled devices can install new applications and
games to make their devices more personal and
adapt them to specific needs.
J2ME CLDC/MIDP
In 1999, Sun regrouped its Java technologies into
three platforms or editions. J2ME (Java 2 Micro
Edition) became the platform targeting “micro”
devices with small processors and memory capaci-
ties, such as mobile phones, communicators and
PDAs. (The other two Java platforms are Java 2
Standard Edition, J2SE, and Java 2 Enterprise Edi-
tion, J2EE™).
J2ME addresses a variety of devices. To handle the
diversity, two concepts have been introduced –
configurations and profiles. A configuration defines
a minimum platform for a family of devices with
similar processing and memory capacities. A pro-
file targets a specific device category within that
family, for instance mobile phones.
Two J2 ME configurations are available:
• CDC, Connected Device Configuration. This
configuration is aimed at devices such as PDAs.
• CLDC, Connected Limited Device Configura-
tion. This configuration is aimed at devices such
as mobile phones and pagers.
Current situation
So far, two profiles have been established for
J2ME:
• MIDP, Mobile Information Device Profile, and
• Personal Profile.
MIDP is connected to the CLDC configuration and
provides developers with essential information and
guidance when writing programs for mobile phones
and two-way pagers.
Personal Profile is linked to the CDC configura-
tion. Targeted at PDAs, this combination replaces
PersonalJava™ in J2ME.
CLDC/MIDP v. PersonalJava
Besides targeting different types of devices, the
main difference between J2ME CLDC and Person-
alJava from a user's point of view is that applica-
tions written in J2ME CLDC can be downloaded
from the Internet. PersonalJava applications are
typically transferred to devices from a PC via cable.
Hand-held computers and mobile phones that sup-
port Java also need a Java interpreter to run the
applications. Since the Java Virtual Machine (JVM)
was not the optimal interpreter for devices with
Figure 5. J2ME in detail