Google's new open-source J2ObjC tool translates Java to Objective-C so Java developers can more easily build apps for the iPhone and iPad.
Google has announced the release of J2ObjC
an open-source command-line tool that translates Java code to Objective-C for
platform so that Java developers can more
easily build apps for the iPhone and iPad.
The goal of the J2ObjC tool is to enable developers to write
an application's non-UI code-such as data access or application logic-in Java,
which can then be shared by Android apps, Web apps (using GWT
the Google Web Toolkit) and iOS, said Google engineer Tom Ball in a recent post
on the Google Open Source Blog.
"J2ObjC enables Java code to be part of an iOS
application's build, as no editing of the generated files is necessary,"
Ball said. "J2ObjC is not a Java emulator, but instead converts Java
classes to Objective-C classes that directly use the iOS Foundation Framework."
The new Google tool supports the full Java 6 language and
most of its runtime features that are 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.
And J2ObjC can be used with most build tools, including Xcode and Make, Ball
According to the J2ObjC project page, the tool is currently
between alpha and beta quality. However, several Google projects rely on it, though
when new projects first start working with it they usually find new bugs to be
fixed, Google said. As nearly every Java developer has a slightly different way
of using Java, the tool has not translated all possible paths yet. It is
released as J2ObjC version 0.5. Developers must use the tool on a Mac OS X
system, with Xcode 4
or higher, Java
for OS X
and Apache Maven
J2ObjC does not provide any sort of platform-independent UI
toolkit, nor are there any plans to do so in the future, Google said. iOS UI
code needs to be written in Objective-C or Objective-C++ using Apple's iOS SDK,
just as Android UIs need to be written using Android's API and Web app UIs
using GWT or other tools.
With a debate raging over whether to develop native, Web or hybrid apps
for mobile platforms,
Google's J2ObjC tool gives developers another choice for building apps for the
popular iOS platform. Facebook CEO Mark Zuckerberg recently noted that one of
Facebook's biggest strategic mistakes was to base its mobile app development
strategy on HTML5 rather than going native.
Nat Friedman, CEO of Xamarin, a maker of tools for creating
fully native apps with device-specific experiences, said, "Two years ago
you might choose to do an iOS app as a first choice because the iPhone was the
leading platform, but now with Android there's a challenge to that. And
developers need tools to support building apps for these platforms."
Xamarin's tools do that for C# developers, and now Java developers can use