What makes Java unique? Actually there are quite a few things that set it apart from other languages, but I want to focus on its true cross-platform presence. No other platform provides the end-to-end tools for building a robust desktop application and deploying it on every major desktop operating system. The best you can hope for with other languages is that you can share most of your business logic across platforms, but when it comes to the user interface, well, you need to build that separately for each platform.
The mobile space, sadly, is a different story. Many devices do use JavaME, but the big players (Android, iOS, Windows Phone, Blackberry) all have their own toolkits that make it difficult to truly write once run anywhere. While Android and Blackberry do use Java as their primary development language, their toolkits are incompatible with each other. iOS and Windows Phone, likewise, are incompatible with each other, and everyone else. What I want is a Java toolkit that does for mobile what Swing (and now JavaFX) did for desktop.
2012 has seen some progress where there was previously only darkness. There are now a handful of solutions that will allow you to write mobile apps with Java (e.g. CodeNameOne, ADF Mobile, J2Objc, Avian, to name a few), but none of these offer the same type of run-once-run-anywhere development experience as Swing did (and JavaFX does now). CodeNameOne, perhaps, comes the closest, as they provide cross-platform libraries for most things, including the UI. My hesitation with this framework is its dependence on their cloud services for building the applications. ADF Mobile includes a small JVM for the business logic, but relies on PhoneGAP (HTML5) for the user interface and for interacting with Phone services. J2Obj is interesting also, as it allows you to compile Java source code to Objective-C code that can be used from your iOS front-end, but this doesn’t get us anywhere near cross-platform development – just easier sharing of code between Android and iOS. Avian, is an alternative, light-weight JVM that provides AOT compilation and has been successfully used to build ARM binaries that can be run on iOS. It provides, perhaps, perhaps the most hope since it is open source. But examples are scarce for iOS, and it isn’t backed by any major players at this time AFAIK.
There seem to be two trends for attacking cross-platform mobile development:
- Write Once, Run Anywhere – Using HTML5 for the UI.
- Share business logic, but use native tools for building and designing the UI.
The problem with the first approach is mostly performance related. HTML5 is great, but on mobile devices you may need to crank as much as you can out of that little processor. The second option solve the performance issue, but it just isn’t as fun. Nor is it as maintainable.
I want what is behind door number 3: Write once, run anywhere, with a rich UI toolkit that is cross-platform but has a pluggable look and feel so that the applications can be made to look native. This UI toolkit should be efficient (perhaps OpenGL) so that we aren’t having to choose between portability and performance to a great degree.
I guess, what I want is JavaFX on mobile (i.e. iOS, Blackberry, Android, and Windows Phone).