What is J2ME, a midlet, a JAD, or a JAR?
Newer phones actually contain a computer chip that can run programs. Sun ® has created a programming language specifically for devices such as these smart phones. It is based on their Java ® language, and it is called the “Java version 2 Mobile Edition” or J2ME. The programs created in J2ME are called midlets. When you download a midlet from a web page, there are two files involved: a JAR file and a JAD file. The JAR file is the “Java Archive,” which is the actual program. The JAD files is a plain text “descriptor” file (i.e., a “(J)ava (A)rchive (D)escriptor”) that tells the phone about the JAR file. When you download a midlet, the phone downloads the JAD file to determine the program’s name, size, version, components, source location, and sometimes the storage destination (into which folder it should be placed). If the JAD doesn’t specify a storage location, the Sanyo 4900 defaults to the “Applications” folder even though it might be a game program. If you’d like to learn how to writ
