In order to properly debug a MIDlet, you must alter some of Eclipse's default settings. The setting changes required are covered in the installation instructions. Click here to see the changes you need to make.
In order to quickly debug a MIDlet, you can simply select Emulated J2ME Midlet from the Debug item.
This will automatically create a Launch Configuration entry using the current default settings, and invoke the debugger.
When you use this option, the Launch Configuration is automatically set up for Midlet launching mode. See here for more details on the different launch modes.
You can manually create a Launch Configuration by selecting either the Run... or Debug... item, clicking on Wireless Toolkit Emulation in the left column and pressing the New button.
By default, the configuration is created for Over The Air debugging. See here for more details on the different launch modes.
As of Eclipse version 3.0M7, it is now possible to debug the KVM that is part of the J2ME emulator. The Emulated J2ME Midlet launch configuration may now be used to debug a MIDlet in the emulator.
NOTE: It is not possible to debug a MIDlet in Over the Air (OTA) mode.