Question

I have a Scala project and I would like to export it as a jar.

*1. At first I tried creating a Java class for the project as an entry point

public class JMain {
 public static void main(String[] args) {
  System.out.println("Java main calling Scala main");
  SMain.main(new String[] {""}); //SMain.main is the actual *main*

and this worked fine and dandy when launched from Eclipse, but when I export it as jar it’ll give me 18 exceptions or so. I do now know how to replicate then “environment” in which Eclipse manages to launch this and I’m prety sure it relies on the fact that Scala is on my system already – I need a self contained jar with everything packed in there.

*2. My second try consisted of trying what lach suggested here How to deploy a Scala project from Eclipse?
namely:

public class JMain {
 public static void main(String[] args) {
  System.out.println("Java Main");
  List<String> argList = new ArrayList<String>();
  argList.add("fully.qualified.ClassName"); //???
  for (String s : args) argList.add(s);
  scala.tools.nsc.MainGenericRunner.main(argList.toArray(new String[0]));

This time it won’t even run from Eclipse, although it gives only 6 or so exceptions starting with the famous NoClassDefFoundError. I have a feeling I’m not getting fully.qualified.ClassName right. *3. If the main Scala class is called “Dis.scala” and is located in package “pack” shouldn’t this fully.qualified.ClassName be “pack.Dis”?

I’m using Jre 1.6 and Scala 2.9.2
EDIT: I have included all external imported jars, even scala-library.jar – everything is nice and packed in the jar

P.S. I am not familiar with Ant or Maven or Sbt. I just want my Scala project jared – if possible without getting into hairy things.

Answer 1

Here is what worked for me:
1. Create scala project
2. Create Wrapper java project
3. Add the scala-library.jar to you java project build path.

So you only need the 3rd step in addition since the rest looks similar to what I did. Then you can happily use: java – jar file.jar

EDIT:
How to create a JAR File which contains Scala/Code which can be consumed by another Java Project, using Scala – Eclipse IDE.

1. Create a new Scala Project and define an object with a main method as entry point.
2. Now create a new Java Project and add your Scala Project to the new ones buildpath. Additionally add the scala-library.jar to the Java project.
3. Now create a Wrapper class in the java project which calls your entry point class from the scala lib. Run the wrapper class to create a eclipse run configuration and test if you can call the scala project.
4. Use the Export->Java->Runnable JAR file, Wizard now on the wrapper project.The eclipse run configuration will be used as entrypoint into the JAR. Depending on your needs you may want to :
   extract required libraries into generated JAR
   or
   Package required libraries into generated JAR

Finally you get a complete packaged JAR which you can use like this:

java – jar wrapped.jar