Xpand your horizons

Xtend – a quick look at the pros and cons of an up-and-coming JVM alternative

Coman Hamilton

It’s got lambdas, it’s flawlessly interoperable with Java and it’s also a cinch to learn for Java devs. So what’s the catch?

“Look at me! Look at me!” The volume of JVM languages
screaming for attention from Java developers is steadily rising.
Somewhere in the deafening crowd of Java alternatives is a small
language called Xtend. “Over here,” it shouts. “I have lambdas! I’m
really smooth and I’m totally easy to learn.”

But can you trust it?

Put simply, Xtend is to Java like JavaScript is to
CoffeeScript: a more concise language that compiles to Java in
order to help devs cut down on their boilerplate code.

Having started out in Xtext, Eclipse’s framework for
developing programming languages, Xtend appeared in the Eclipse
release train in 2011, and has since proven itself a handy language
for Android developers. One commentator
even goes so far as to call it Android’s answer to Swift.

As you can see in the Hello World example, Xtend runs
pretty much like Java – except for the use of def to declare a

class HelloWorld {

def static void main(String[] args) {

  println("Hello World")



With a “look and feel” that could be compared to Groovy, this
statically-typed language adds quite a few gems to the feature list
of other JVM languages: a null-safe feature call, more prevalent
final variables, being able to clean up RxJava boilerplate,

Flawless interoperability, yay!

Xtend has at least one major bragging point where JVM
alternatives like Scala, Clojure and Groovy are lacking: error-free
interoperability with Java. Xtend can do this because it looks and
works exactly like Java’s type system, so there’s no chance of any
impedance mismatches between Java and Xtend code.

Essentially, this means you can invoke code from Java
and vice versa, but best of all, this makes learning Xtend easy for
anyone that’s already familiar with Java’s type system. Co-creator
Sven Efftinge told
 the idea behind Xtend is to “free developers from
the limitations of Java without tearing them into a whole new
world.” That’s a major plus for would-be alternative programmers
that don’t have time to get their head around the foreign syntaxes
of Groovy and Scala.

Can I get that with lambdas?

Xtend also gives you the chance to use your favourite
new Java function: lambdas – perhaps nothing to write home about
for those of us already on Java 8. But then again, Xtend’s lambdas
compile to anonymous inner classes, which is perfect for Android
developers that need that function for click listeners.

Size and readability also rank pretty high for Xtend,
especially for mobile devs as Efftinge explains: “Android apps
written in Xtend are as fast as if they were written in Java but
the written code is much more readable.”

No IntellijIDEA support, boo!

As developer Andre Medeiros explains in a lengthy blog
post, Xtend is still far
from perfect
. One of the biggest drawbacks is the lack of
support for
. So far, Xtend has most been an endeavour of the
Eclipse Foundation, although an appeal has
been started for an IntelliJIDEA plug-in. Another problem, Medeiros
notes, is the additional compilation step when building an apk,
which means an Android application needs around 20 entire seconds
to compile an entire project –  life’s short enough as it is,

If you’d like to Xtend your knowledge (sorry, couldn’t
resist) about the nifty features of this JVM alternative, check out
the extensive
or this video about using Xtend for code

Coman Hamilton
Before becoming Editor of JAXenter.com (S&S Media Group), Coman completed an M.A. in Cultural Studies and wrote for numerous websites and magazines, as well as several ad agencies. // Want to submit a story? Get me at coman[AT]jaxenter.com or linkedin.com/in/comanhamilton
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