i tried the command
Display.getInstance().setDefaultVirtualKeyboard(null);
it disabled luiwt virtual keyboard as well as the system virtual keyboard..
how to disable lwuit virtual keyboard and show platform built-in virtual keyboard.
Native VKB works by default for both Android & RIM devices.
It can't be supported on MIDP devices since the MIDP API's have no provisioning for VKB's. The only way to get it to work on Nokia devices (etc.) is to keep it constantly on through a jad property.