vaadin-framework/documentation/getting-started/getting-started-scala.asciidoc

---
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.

This document will help you to set up a **Hello World** project in Vaadin with Scala using Maven.

*It is assumed you already have Java and Maven pre-installed.*

## Getting Started
* Run the Maven archetype below to get a simple app created:
```bash
mvn archetype:generate -DarchetypeGroupId=com.vaadin -DarchetypeArtifactId=vaadin-archetype-application -DarchetypeVersion=8.0.5 -DgroupId=com.pany -DartifactId=ui -Dversion=1.0-SNAPSHOT -Dpackaging=war
```
_Note that at this point you could import the project to and IDE like IntelliJ._

* You now should have the Vaadin Java project under the directory `ui`. Since we are doing Scala, delete the `java` directory in `${project_home}/src/main/` and create an empty `scala` directory in the same place.

* Add the following Scala dependency and...
```xml
  <dependency>
   <groupId>org.scala-lang</groupId>
   <artifactId>scala-library</artifactId>
   <version>2.12.1</version>
  </dependency>
```
...plugin to your 'pom.xml'
```xml
  <plugin>
   <groupId>net.alchim31.maven</groupId>
   <artifactId>scala-maven-plugin</artifactId>
   <version>3.2.2</version>
   <executions>
    <execution>
     <goals>
      <goal>compile</goal>
      <goal>testCompile</goal>
     </goals>
    </execution>
   </executions>
   <configuration>
    <scalaCompatVersion>2.12</scalaCompatVersion>
    <scalaVersion>2.12</scalaVersion>
   </configuration>
  </plugin>
```

* Create the following class in the new-created `scala` directory.
```scala
package com.mycompany.myproject

import java.util.Date
import javax.servlet.annotation.WebServlet

import com.vaadin.annotations.{Theme, VaadinServletConfiguration}
import com.vaadin.server.{VaadinRequest, VaadinServlet}
import com.vaadin.ui.Button.{ClickEvent, ClickListener}
import com.vaadin.ui._

@WebServlet(urlPatterns = Array("/*"), name = "MyScalaUIServlet", asyncSupported = true)
@VaadinServletConfiguration(ui = classOf[MyScalaUI], productionMode = false)
class MyScalaUIServlet extends VaadinServlet {
}

@Theme("mytheme")
class MyScalaUI extends UI {

  override def init(request: VaadinRequest): Unit = {
    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 from Scala!",
      new ClickListener {
        override def buttonClick(event: ClickEvent): Unit =
          Notification.show("The time is " + new Date)
      })
  }
}
```

* Now just execute:
```bash
mvn clean package jetty:run -Dvaadin.productionMode=true
```

* You should get logs containing something similar to:
```bash
[INFO] Started ServerConnector@15e41fff{HTTP/1.1,[http/1.1]}{0.0.0.0:8080}
[INFO] Started @9194ms
[INFO] Started Jetty Server
[INFO] Using Non-Native Java sun.nio.fs.PollingWatchService
```
_The important information here is that Jetty is now running on port 8080_

* Go to `localhost:8080` from the web browser and the page should be working:

image::img/hello-world-scala-page.png[]

* If you can see the page above, congratulations you have created your first Vaadin with Scala app.

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[]