Hemanta Sapkota has developed an Eclipse plug-in that adds support for J2ObjC development. From the project's site:
J2ObjC Eclipse Plugin, as the name says is an Eclipse plugin for interfacing Google's j2objc compiler in Eclipse. It allows you to generate Objective-C source codes from existing Java projects in Eclipse. In addition, most of the command line parameters required by the j2objc compiler is supported as preferences in the plugin.
Since J2ObjC is focused on iOS development and so only runs on Macs, the J2ObjC Eclipse Plugin also requires a Mac OS X system.