How to set up Java and Scala in one single Module in Intellij IDEA 11?

Question

I have got IntelliJ 11. I use Maven for dependency management.

I want to create one module which contains Java and Scala source files. I have already added a folder "src/main/java" and "src/main/scala" under Project Settings => Module => "Module XYZ". The Scala facet is also added already.

What do I need to make IntelliJ compile both correctly?

Answer 1

To create a new project that uses Scala:

1. In "New Project" wizard check "Scala" in technologies list.
2. Provide a path to Scala installation (if not detected)

To add a new module that uses Scala into existing project:

1. In "Add Module" wizard check "Scala" in technologies list.
2. Provide a path to Scala installation (if not detected)

To add Scala support to existing module:

1. Right-click the module in Project View, choose "Add Framework Support..."
2. Check "Scala" in technologies list (unavailable if module has Scala facet attached)
3. Provide a path to Scala installation (if not detected)

To manually configure existing module:

1. Create library "scala-compiler":

   • Classes:

     • scala-compiler.jar
     • scala-library.jar

2. Create library "scala-library":

   • Classes:

     • scala-dbc.jar
     • scala-library.jar
     • scala-swing.jar

   • Sources:

     • scala-dbc-src.jar
     • library-src.jar
     • swing-src.jar

Docs: /doc/scala-devel-docs/api/

(if you downloaded Scala as an archive, you need to get separate API docs archive and extract it so that \doc\scala-devel-docs\api exist; if you installed Scala using LzPack, then API docs are already there)

3. Add Scala facet to the module, select "scala-compiler" library as compiler library
4. Add "scala-library" to module dependencies.

Hints:

• Don't add Scala compiler library to module dependencies (unless you really need Scala compiler classes in your code)
• Remember to attach "scala-library*.jar" to Scala compiler library, it's a dependency of "scala-compiler*.jar" itself.

Source: Project-configuration-explained

Answer 2

I did not find a good Google result first. Got it working now. This site explains it very clearly:

http://devnet.jetbrains.net/thread/290032