DoYes

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

DoJa and i-mode

DoJa is closely linked to the i-mode technology from NTT Docomo and not only has a Java profile especially for mobile devices, but also support for downloading mobile applications to i-mode-enabled cell 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 intended.

The development of applications on mobile devices brings with it some restrictions that have to be observed when developing DoJa applications. This is particularly about restrictions on screen size and processor performance. A DoJa application is programmed and compiled by a content provider . The tool "iapplitool" provided by NTT DoCoMo for free download is used for this purpose. In addition to the compiler, it also contains a simulator for DoJa (see web links).

Users download the programs from the content provider and run them on their DoJa-enabled mobile device. It is up to the content provider whether the applications can run independently of an existing connection to the Internet or only with an existing connection to the Internet. If the applications can only run when there is an existing connection, the content provider can control subscriptions to the applications (i-mode subscription model). The user can delete the applications from the device's memory at any time.

DoJa applications can call up various cellular-specific functions directly from the program after confirmation by the user. For example, this can be the generation of an SMS or MMS , a camera function (taking a picture), establishing a connection to another mobile phone subscriber, using the infrared port or automatic entries in the terminal's calendar.

Versions

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

The current international and European versions of DoJa are DoJa 1.5 and, since mid-2005, DoJa 2.5. DoJa 2.5 include additional functions, such as B. 3D representation. Both versions are also available as a lite version with limited functionality . Other versions such as DoJa 3.0, DoJa 3.5 and DoJa 4.0 are already available in Japan.

Another Java profile for mobile devices is MIDP .

Files

The following files are available for a DoJa application.

  • 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 thus enables downloading.

Sample code

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

import com.nttdocomo.ui.*;
public class helloworld extends IApplication {
      public void start() {
	 Dialog d = new Dialog(Dialog.BUTTON_OK,"Message");
                d.setText("Hallo Du !");
                d.show();
	System.exit(0);
      }
}

Web links