PersonalJava

Developers Guideline UIQ C++ and PersonalJava

This section offers advice about developing PersonalJava applications. This requires Symbian OS envi- ronment specific knowledge not needed for MIDP application development.

PersonalJava (referred to as “pJava” in this document) was one of the first Java programming environ- ments targeted for development of applications for resource-constrained devices. These devices include PDAs (Personal Digital Assistants) and Communicators/Smartphones. pJava specifies a reduced set of class libraries compared to a desktop environment and historically represented the first attempt at select- ing desktop level APIs suitable for the Java runtime environment of a high-end mobile device.

Over the years the Symbian port of pJava to Symbian OS has been undergoing substantial optimization (assembler coded byte code interpreter, optimized AWT library and so on) that today, in combination with hardware performance advancements, make this a powerful alternative for realizing mobile applications. pJava is supported on both P800, P900 and P910 series, and is provided as an alternative to using Sym- bian OS C++ for feature-rich third party applications.

Applications developed in pJava do not have access to the hardware and functions of the phone unless you use the Java Native Interface (JNI) and write the access procedures in C++. Your applications written in pJava will probably run slower than a corresponding application written in C++, however they are typi- cally easier to write. As previously stated, this does not mean to imply that pJava applications will not per- form well. You can access the features of the phone by using JNI to access C++ DLLs to access the features of the phone available to C++ applications.

Note:

JavaPhone APIs is not available on P800, P900 and P910 series and there is no direct Bluetooth access.

For more information on programming in pJava, download the self training course from Sony Ericsson Developer World, see links.

Additional tools useful to the pJava developer

•The Sun Microsystems Inc. specification of Personal Java (PJAE). This document describes the subset of a JDK 1.1.x generation class library that is supported by a pJava edition. The P800, P900 and P910 series pJava runtime environment corresponds to version 1.1.1a (http://java.sun.com/products/personaljava/spec-1-1-1/pjae-spec.pdf)

•A copy of the Sun Microsystems Inc. “JDK” (Java Development Kit).

•If you intend to use the JDK standalone to carry out the compilation of Java source code from a DOS command shell to be executed on P800, P900 and P910 series, you should download and install the JDK.1.8_010 at

http://java.sun.com/products/archive/jdk/1.1.8_010/index.html, which closely corresponds to the pJava evolution. It has formally passed the “Sun End of Life process” but may still be preferred for this usage, since it does not offer more advanced Java features and class library than supported by the Symbian Java runtime, thus reducing the risk of code incompatibility.

14	October 2004