This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
It depends on the mobile. However, JRE anything (and 1.4 is now obsolete) isn't generally found on mobile devices. The full JRE was originally too big to fit - although once you start talking smartphones with 8GB of RAM, obviously that's no longer a problem. But the mobile device CPUs are usually fairly slow (partly so they'll use less battery power).
So, in short, the runtime environment for J2ME is J2ME. Or JME, these days.
Unless, of course, you're talking a device with something like Android in it. Which is another Java entirely.
An IDE is no substitute for an Intelligent Developer.