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Eclipse Java ME (J2ME) Developer Guide
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Device Management

This document describes the management of device definitions in MTJ.

Device Management Preferences

In order to use MTJ, you must configure at least one Device Definition. Device management in MTJ allows significant control over the device definitions available to MIDlet Suites and emulator launching. Devices are managed from within the Preferences dialog of Eclipse. To reach the device management functionality:

  1. Select the Preferences menu item from Eclipse's Window menu.

  2. Expand the Java ME item in the pane to the left and click on Device Management.

The Device Management page displays the devices that are currently known to MTJ. From this page, it is possible to import new devices, redefine current devices and remove definitions.

The Default column allows a single device to be chosen as the default. The default device will be initially selected when creating new MIDlet suites and emulator launch configurations.

Importing Devices

MTJ is aware by default of a number of different types of wireless toolkits and their associated structure. These devices can be imported into MTJ automatically for use by project definitions and emulator launching.

  1. Select Import...
  2. In the resulting dialog, select the root directory to be searched to find known devices definitions.


    As you leave the search directory text field or select the Refresh button, MTJ will begin looking for devices in the specified directory and all subdirectories. As of version 1.5.0 of MTJ, it is no longer necessary to pick the "perfect" directory in order to have devices imported, as MTJ should be able to locate them if they reside anywhere within the specified directory. MTJ will display the devices that are found as they are found. If you wish to stop the search at any time, select the Cancel button. After the search has completed, use the checkboxes to select the device definitions to be imported. Finally, choose Finish to complete the import process.

  3. When you have successfully completed adding the device, you should see the imported devices in the device management preferences.

    Save the definitions by selecting Finish.

Duplicate a Device Definition

In certains cases, you may find that an imported device definition is close to what you would like but could use a few small changes. In a case like this, you may use the Duplicate button to create an exact copy of the selected device definition. The duplicated device definition can then be altered as necessary without changing the original.

NOTE: It is not a requirement that you duplicate a device prior to altering it. If you make changes to an imported device and you would like to get back to the original, simply remove the device definition and re-import it.

Edit a Device Definition

MTJ attempts to understand many of the wireless toolkits that are available to developers. Unfortunately, keeping up with the different vendors and the various ways that toolkits are structured is very difficult. Even in cases that MTJ is able to identify and import a device definition, it is possible that it might be incorrect or not quite what you were looking for. Select the Edit... button to launch the edit dialog.

The tabbed dialog provides control over the definition of a device, including the emulator executable, launch command and libraries that define that device. When the edit dialog is opened, the contents will be filled to match the selected device definition. When all changes have been completed, select the OK button on the dialog and OK on the device management preferences.

Basic Properties

The first tab of the edit dialog presents many of the properties that make up the definition of the device. Each of these properties works together to provide the environment necessary for MTJ and care must be taken when making changes. For more information on configuring the properties available on this page, see Editing Basic DeviceProperties.


The Libraries tab of the edit dialog allows the selection and configuration of the libraries that make up the device definition. Using the controls on this page, it is possible to add and remove functionality from a device definition. This is useful in restricting available API's to create a more generic project. See Editing DeviceLibraries for more details.

Advanced Properties

The Properties tab of the edit dialog displays the properties defined by the selected device. Properties may not be altered at this time.

Example: Creating a MIDP 1.0 Device

In many cases, importing devices will result in a device with greater functionality than might be required for testing. It is possible to create a device definition using device management. For example, using the standard wireless toolkit, creation of a MIDP 1.0 device can be done with the following steps.

  1. Open the Device Management preferences.
  2. Duplicate the device that is closest to what you want. For instance, choose the DefaultColorPhone.
  3. Edit the copy of the device device.
  4. On the basics page, alter the launch command template.
    Change -Xdevice:%device% to be -Xdevice:DefaultColorPhone (without the quotes).
  5. Switch to the libraries page of the editor dialog.
  6. Use Add... to add cldcapi10.jar. It should automatically be recognized as CLDC 1.0.
  7. Remove the original cldcapi11.jar.
  8. Use Add... to add midpapi10.jar. It should automatically be recognized as MIDP 1.0.
  9. Remove the original midpapi20.jar.
  10. Press OK to commit the edits to the device.
  11. Press OK on the preferences dialog.

  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire