- Download and install a JDK and one of the supported Java mobile toolkits.
- Make sure that the J2ME plugin is enabled, see Making sure that the J2ME plugin is enabled.
- Define the JDK and the mobile toolkit in IntelliJ IDEA. (In IntelliJ IDEA, the supported Java mobile toolkits are referred to as mobile SDKs). See Defining a JDK and a mobile SDK in IntelliJ IDEA.
- Create a project with a J2ME module, see Creating a project with a J2ME module.
- If necessary, configure the compilation settings specific to Java mobile applications, see Configuring Java mobile-specific compilation settings.
See also, Running and debugging Java mobile applications. For general instructions, see IntelliJ IDEA Usage Guidelines.
Even though the J2ME plugin is enabled by default, it's always worth making sure that this plugin is still enabled before you start developing a Java mobile application. To do that:
- Open the Settings dialog (e.g. Ctrl+Alt+SCommand Comma).
- In the left-hand part of the dialog, under IDE Settings, select Plugins.
- In the right-hand part of the dialog, on the Plugins page, type j2 in the search box. As a result, only the plugins whose names and descriptions contain j2 are shown in the list of plugins.
- If the check box to the left of J2ME is not selected, select it.
- Click OK in the Settings dialog.
- If suggested, restart IntelliJ IDEA.

(a.k.a. WTK),
versions 1.x and 2.x.