Mobile Software So you want to download a gambling application and you are being told something about JARs and downloading them, and possibly JADs too?

Until recently I too thought jars were where you keep your jam so what has that got to do with your phone?

It’s all to do with “Java“. In this context Java is not the type of coffee or the South East Asian island, it’s what the phone applications (or games) are written in. It’s a language that most phones understand. If you read your phone’s spec. it shows up as either Java, J2ME, or MIDP all of which means this phone can “speak” java.

A “jar” file is a “Java Archive” like a zip file. It’s a way of delivering lots of files like graphics to your phone in one easy download. Your phone sees this file as an application that can be run.

Fine but what’s a “JAD” you say?

A JAD is ‘Java Application Description’ which is a fancy way of saying it’s a file that tells your phone all about the JAR. It tells it, amongst other things, what it’s called, how big it is, and how to run it. Armed with this info your phone can run the JAR application for you — without it the phone would be a little confused. The two files are usually sent as a pair. The JAD is always sent first as it contains the information the phone needs to get the JAR and install it.

Once it has the JAD, which is a very small file so you may not see the download on your screen, it goes to get the JAR and you phone will automatically download and install it for you. When the process is over you can just select the icon in your phone’s menu and you are up and running.