j2objc - A Java to iOS Objective-C translation tool and runtime
J2ObjC is an open-source command-line tool from Google that translates Java source code to Objective-C for the iOS (iPhone/iPad) platform. This tool enables Java source to be part of an iOS application's build, as no editing of the generated files is necessary. The goal is to write an app's non-UI code (such as application logic and data models) in Java, which is then shared by web apps (using GWT), Android apps, and iOS apps.
J2ObjC supports most Java language and runtime features required by client-side application developers, including exceptions, inner and anonymous classes, generic types, threads and reflection. JUnit test translation and execution is also supported.