DoJa stands for " DoCoMo Java" and is a proprietary object-oriented programming language based on Java, specifically on the J2ME (Java 2 Platform Micro Edition ) is based.

DoJa and i-mode

DoJa is closely linked to the i-mode technology of NTT Docomo and not just a Java profile specifically for mobile devices, but also a support for the download of mobile applications on i-mode -enabled mobile phones. DoJa applications must always be downloaded over a mobile network. A copy of programs via Bluetooth, the infrared port or a computer is not provided.

The development of applications on mobile devices brings some restrictions with it, which must be considered in the development of DoJa applications. This goes especially to limitations in screen size and processing power. A DoJa application is programmed and compiled in a content provider ( " Content Providers "). The purpose of the system provided by NTT DoCoMo for free download tool " iapplitool ", which contains the compiler and a simulator for DoJa (see links).

Users download the programs at the content provider, and run them on their DoJa -enabled mobile device. It is up to the content provider to determine whether the applications are independent from an existing connection to the Internet, or only when a connection to the Internet executable. If the applications are only run when connected, the content provider can be as subscriptions to the applications control ( i-mode subscription model). The applications can be deleted anytime by the user from the memory of the terminal.

DoJa applications to different mobile- specific functions, after confirmation by the user, call it directly from within the program. For example, this be the generation of an SMS or MMS, a camera function ( taking a picture ), set up a connection to another mobile subscriber, the use of the infrared ports or automatic entries in the calendar of the terminal.


DoJa was developed by NTT Docomo Inc. and Sun Corporation. The first version DoJa 1.0 was released in Japan in 2001 by NTT DoCoMo.

The current international and is currently available in Europe versions of DoJa are DoJa 1.5 and since mid-2005 DoJa 2.5. DoJa 2.5 include additional functions, such as 3D representation. Both versions are also available with limited features than lite version. More versions as DoJa 3.0, 3.5 and DoJa DoJa 4.0 are already available in Japan.

A further Java profile for mobile devices is MIDP.


For a DoJa application there are the following files.

  • The source code with the extension *. java
  • The compiled program *. jar (Java Application Resource )
  • The description file *. jam or *. adf ( Application Descriptor File)
  • An HTML page that references the description file and allows the download.

Sample Code

Simple DoJa program with a message " Hello There!" and an OK button:

Com.nttdocomo.ui import *. ; public class helloworld extends IApplication {        public void start () {           Dialog d = new Dialog ( Dialog.BUTTON_OK, " Message");                  d.setText ( " Hello There!" );         ();          System.exit (0);        } } Web Links

  • Http:// - DoJa Developer Network (English)
  • Http:// - i-mode for developers ( in English )
  • Http:// - English DoJa Tutorial by KPN
  • Java ( programming language)
  • Mobile
  • Abbreviation