JAD files are associated with Java applications and are used to describe Java ME applications which are known as MIDlets. It is a class of Java which provides the interface between the Java application and the operating system in MIDP (Mobile Information Device Profile). This is a primary element of the Java 2 Platform and when it is integrated with a CLDC (Connected Limited Device Configuration) MIDP is able to offer a standard JRE (Java Runtime Environment) for a mobile device.
JAD stands for Java Application Descriptor since JAD files describe MIDlets which are in turn distributed as JAR files used for distributing programs written in Java and used by the Java Runtime Environment. MIDlets are typically used for games and applications for the Java Micro Edition, which is also known as J2ME and used with mobile platforms. JAD files can also be used to identify and retrieve MIDlets and install them on mobile platforms.
JAD files contain data and information related to Digital Rights Management which is used to protect the copyrights for electronic media and other data used to package Java games and applications for mobile devices.
How to Open JAD Files
Files that contain the JAD extension are created by Oracle-Sun Java and are typically delivered to your mobile device using the Internet. They are commonly loaded from a website and cannot be manually installed on your device.
If you use the Windows, you can open JAD files using any text editor since JAD files are text-based. NotePad or WordPad works well for opening JAD files, so you can view the file contents. Simply right click on the JAD file you want to view and then choose Open With from the drop-down menu. Select either NotePad or WordPad from the list or click Browse if you do not see the program in the list. Once you click on the program, you should be able to open the JAD file in the text editor.
You can also open JAD files in Windows using LogoManager MobiMB Mobile Media Browser which allows you to browse your gallery to drag and drop images, MIDI files, photos and Java MIDIets on your phone and from the hard drive of your PC. You can also use JADMaker which allows you to create JAD files for JAR Java games, so you can install them on your mobile device. JADMaker is available as a free download from the CNET website.
For MacOS X you can use the TextEdit program and for the Linux operating system you can use gedit which is open source and works with a variety of file extensions including JAD files.