Cannot add scala swing dependency via Gradle in Scala IDE

Question

I am a beginner learning Scala. I am on Windows 8.1, using Scala IDE 4.0.0 and Gradle with scala and eclipse plugins to create a project, in which I want to use scala.swing and javax.media packages. I add both libraries as dependencies in build.gradle, only javax.media works.

The steps I have done are:

1. create folders and files as follows

   foo
    |-src
       |-main
          |-scala
              |-Foo.scala
    |-build.gradle
   

   where build.gradle is Gradle build script and Foo.scala is a Scala script, as shown below

   <<build.gradle>>

   apply plugin: 'scala'
   apply plugin: 'eclipse'
   
   repositories {
     mavenCentral()
   }
   
   dependencies {
     compile 'org.scala-lang:scala-swing:2.10.4'
     compile 'javax.media:jmf:2.1.1e'
   }
   

   <<Foo.scala>>

   import javax.media.Player //no error
   import scala.swing._ //error: object swing is not a member of package scala
   
   class Foo {
   }
   

2. using command line, navigate to foo and run gradle eclipse

3. in Scala IDE, do import -> General -> Existing Projects into Workspace -> Browse -> Foo

Then, I get an error at Foo.scala, line 2, which reads object swing is not a member of package scala. And the Referenced Libraries list on the left panel shows only jmf-2.1.1e.jar for javax.media, as shown in the picture below

<<.classpath>>

<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="output" path="bin"/>
<classpathentry kind="src" path="src/main/scala"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER" exported="true"/>
<classpathentry kind="con" path="org.scala-ide.sdt.launching.SCALA_CONTAINER" exported="true"/>
<classpathentry kind="lib" path="C:/Users/mm/.gradle/caches/modules-2/files-2.1/javax.media/jmf/2.1.1e/fe9287a362578bfb8b7b9dba42af0ec80a297abb/jmf-2.1.1e.jar" exported="true"/>
</classpath>

I have tried to configure Eclipse's build path and add scala-swing.jar manually, which works okay, but then I have to do this every time I run the Gradle build script. Please suggest why scala-swing-something.jar did not get imported by Gradle, and how to fix it.

---

This is the logging message after running $ gradle dependencies:

$ gradle dependencies
:dependencies

------------------------------------------------------------
Root project
------------------------------------------------------------

archives - Configuration for archive artifacts.
No dependencies

compile - Compile classpath for source set 'main'.
+--- org.scala-lang:scala-swing:2.10.4
|    \--- org.scala-lang:scala-library:2.10.4
\--- javax.media:jmf:2.1.1e

default - Configuration for default artifacts.
+--- org.scala-lang:scala-swing:2.10.4
|    \--- org.scala-lang:scala-library:2.10.4
\--- javax.media:jmf:2.1.1e

runtime - Runtime classpath for source set 'main'.
+--- org.scala-lang:scala-swing:2.10.4
|    \--- org.scala-lang:scala-library:2.10.4
\--- javax.media:jmf:2.1.1e

testCompile - Compile classpath for source set 'test'.
+--- org.scala-lang:scala-swing:2.10.4
|    \--- org.scala-lang:scala-library:2.10.4
\--- javax.media:jmf:2.1.1e

testRuntime - Runtime classpath for source set 'test'.
+--- org.scala-lang:scala-swing:2.10.4
|    \--- org.scala-lang:scala-library:2.10.4
\--- javax.media:jmf:2.1.1e

zinc - The Zinc incremental compiler to be used for this Scala project.
No dependencies

BUILD SUCCESSFUL

Total time: 11.159 secs

Answer 1

I had the same issue. I think it was an incompatibility between the Scala version and the Scala Swing version. I had these dependencies:

dependencies {
    compile 'org.scala-lang:scala-library:2.11.5'
    compile 'org.scala-lang:scala-swing:2.10.4'
}

To solve this, add the scala-library-all dependency instead:

dependencies {
    compile 'org.scala-lang:scala-library-all:2.11.5'
}

You can leave it at that, but it will add all sorts of dependencies that you might not need. If you don't want that, invoke:

gradle dependencies

It will tell you what dependencies Gradle has found. Mine said, among other things:

compile - Compile classpath for source set 'main'.
+--- org.scala-lang:scala-library-all:2.11.5
|    +--- org.scala-lang:scala-library:2.11.5
|    +--- org.scala-lang.modules:scala-swing_2.11:1.0.1
|    |    \--- org.scala-lang:scala-library:2.11.0 -> 2.11.5

Note the Scala Swing dependency, which has a different name and version from the one I had specified. Copy-and-paste that into your build.gradle dependencies:

dependencies {
    compile 'org.scala-lang:scala-library:2.11.5'
    compile 'org.scala-lang.modules:scala-swing_2.11:1.0.1'
}

And voilà:

gradle cleanEclipse eclipse

All dependencies work!

Answer 2

This looks like Gradle couldn't resolve the org.scala-lang:scala-swing:2.10.4 dependency when it generated the Eclipse files. I use IntelliJ and it does the same thing- everything looks to have worked ok, but dependencies are missing- very frustrating.

You can check by running

$ gradle dependencies

And checking that scala-swing is being resolved correctly. I checked Maven central and you definitely have the dependency listed correctly. If this shows no errors try cleaning your project files and regenerating.