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---
title: Using Vaadin with Scala
order: 1000
layout: page
---
[[getting-started.scala]]
= Using Vaadin with Scala
You can use Vaadin with any JVM compatible language, such as Scala or Groovy.
There are, however, some caveats related to libraries and project set-up. In the
following, we give instructions for creating a Scala UI in Eclipse, with the
Scala IDE for Eclipse and the Vaadin Plugin for Eclipse.
. Install the link:http://scala-ide.org/[Scala IDE for Eclipse], either from an
Eclipse update site or as a bundled Eclipse distribution.
. Open an existing Vaadin Java project or create a new one as outlined in
<<dummy/../../../framework/getting-started/getting-started-first-project#getting-started.first-project,"Creating
and Running a Project with Eclipse">>. You can delete the UI class created by
the wizard.
. Switch to the Scala perspective by clicking the perspective in the upper-right
corner of the Eclipse window.
. Right-click on the project folder in [guilabel]#Project Explorer# and select
"Configure > Add Scala Nature".
. The web application needs [filename]#scala-library.jar# in its class path. If
using Scala IDE, you can copy it from somewhere under your Eclipse installation
to the class path of the web application, that is, either to the
[filename]#WebContent/WEB-INF/lib# folder in the project or to the library path
of the application server. If copying outside Eclipse to a project, refresh the
project by selecting it and pressing kbd:[F5].
+
You could also get it with a Maven dependency, just make sure that the
version is same as what the Scala IDE uses.
You should now be able to create a Scala UI class, such as the following:
[source, scala]
----
@Theme("mytheme")
class MyScalaUI extends UI {
override def init(request: VaadinRequest) = {
val content: VerticalLayout = new VerticalLayout
setContent(content)
val label: Label = new Label("Hello, world!")
content addComponent label
// Handle user interaction
content addComponent new Button("Click Me!",
new ClickListener {
override def buttonClick(event: ClickEvent) =
Notification.show("The time is " + new Date)
})
}
}
----
Eclipse and Scala IDE should be able to import the Vaadin classes automatically
when you press kbd:[Ctrl+Shift+O].
You need to define the Scala UI class either in a servlet class (in Servlet 3.0
project) or in a [filename]#web.xml# deployment descriptor, just like described
in
<<dummy/../../../framework/getting-started/getting-started-first-project#getting-started.first-project.exploring,"Exploring
the Project">> for Java UIs.
ifdef::web[]
The link:https://github.com/henrikerola/scaladin[Scaladin add-on] offers a more
Scala-like API for Vaadin. A Vaadin 7 compatible version is under development.
endif::web[]
ifdef::web[]
[[getting-started.scala.lambdas]]
== Defining Listeners with Lambda Expressions
Scala does not support use of lambda expressions for calling functional
interfaces, like Java 8 does. Hence, we can't just use a lambda expression for
the [interfacename]#ClickListener# in the example above. You can, however,
define implicit conversions from lambda expressions to such interface
implementations. For example, for click listeners:
[source, scala]
----
implicit def clickListener(f: ClickEvent => Unit) =
new ClickListener {
override def buttonClick(event: ClickEvent) {
f(event)
}
}
----
You could then use a lambda expression as follows:
[source, scala]
----
content addComponent new Button("Click Me!",
(event: ClickEvent) =>
Notification.show("The time is " + new Date))
----
endif::web[]
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