One step beyond Java

A JVM language with a difference: Eclipse Xtend (now with Android)

Chris Mayer

Eclipse’s statically-typed JVM language has just received a bumper update. We talk to co-creator Sven Efftinge about the newest features.

The number of JVM languages competing for the attention of
Java developers is never-ending, all offering different modern
language concepts that go beyond bog-standard Java. But what if you
haven’t got the time to learn the new syntax and frameworks that
come with Groovy, Clojure and Scala?

A relatively new JVM language that compiles
to Java in a method similar to CoffeeScript
offers a new approach – to simply leverage the best within
Java and cut down excessive boilerplate code.

First appearing in an Eclipse release train last year,
statically-typed Xtend claims
to offer the modern features seen in
other JVM languages, such as closures, but without
throwing the baby out with the bath water

“The idea is to free developers from the
limitations of Java without tearing them into a whole new world,”
co-creator Sven Efftinge told JAXenter.
“It translates directly to Java source and is also otherwise
designed to fit into Java projects seamlessly.”

“In fact Xtend works better with many Java
libraries than Java itself does, as it is designed for Java taking
existing idioms into account,” he boasts.

Efftinge is keen to point out that Xtend offers
“the expressive power” of other languages like Lisp, Smalltalk,
Ruby and Scala, but “without compromising interoperability and tool
support,” favouring to use existing Java tools and

Xtend’s latest release, which is out today,
enters new terrain with comprehensive support for Android
– adding debugging compatible with the Dalvik VM and a Maven
archetype. Efftinge believes that Xtend is as much for
the developers coding for the mobile platform as those developing
with Java.

“[They] face the same limitations in terms of
expressiveness,” says Efftinge. “Android
apps written in Xtend are as fast as if they were written in Java
but the written code is much more readable.” The Xtend founder says
that because the language doesn’t have a heavy library with it, the
footprint of resulting Android apps is “pretty small”.

Xtend’s biggest change at the language level is
the inclusion of macros, through a provisional API called ‘Active
Annotations’. Developers can now declare annotations, to tell the
compiler how to translate Xtend elements into Java.

Efftinge describes Active Annotations as “a
secret weapon” for classical programming problems.

“You can for instance declare an annotation
@Observable, annotate fields with it and get observed setter
methods automatically generated,” he explains, before adding that
changes happen on the fly.

Other new language features include collection literals,
extension variables and extra support for declaring enums. You can
check out the project homepage
for more information, and all the latest changes can be found
in the Eclipse
release notes

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