sbt - How to run jar generated by package (possibly with other jars under lib)?

Question

How can I run .jar file which is generated by sbt's package?

I created a really simple example with a single .scala source:

package org.pack {
    class ScalaParser(files: Array[String]) {
        def doAll() = {
            println("hello")
        }
    }

    object Main {
        def main(args: Array[String]): Unit = {
            val sp = new ScalaParser(args)
            sp.doAll()
        }

    }
}

After running

$ sbt
> compile
> package

.jar is created in /target/scala-<version>. If I try to run it, it fails giving this error:

$ java -jar package_2.9.2-0.1.jar 
Exception in thread "main" java.lang.NoClassDefFoundError: scala/ScalaObject
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at org.pack.Main.main(Main.scala)
Caused by: java.lang.ClassNotFoundException: scala.ScalaObject
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    ... 13 more

Note that no external libraries are used and sbt compile run works fine.

I attached the whole project including generated .jar on dropbox.

What is really weird is the fact that .jar Manifest contains right class to load, i.e. org.pack.Main. Maybe it is caused by something else.

System info

$ java -version
java version "1.7.0_55"
OpenJDK Runtime Environment (IcedTea 2.4.7) (7u55-2.4.7-1ubuntu1)
OpenJDK 64-Bit Server VM (build 24.51-b03, mixed mode)

$ scala -version
Scala code runner version 2.9.2 -- Copyright 2002-2011, LAMP/EPFL

Additional question - what if I had some external .jars in /lib? How can I assure that they are packed? I need one .jar runnable on (possibly) every JVM.

Thanks for help.

Answer 1

You can use the sbt plugin sbt-assembly:

sbt-assembly >= 0.12.0 with sbt >= 0.13.6

Since sbt-assembly is now an auto plugin, it is sufficient to add project/assembly.sbt to your sbt project:

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.5")

sbt-assembly 0.11

Add project/assembly.sbt to your sbt project:

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.11.2")

Add assembly.sbt as well:

import AssemblyKeys._ // put this at the top of the file

assemblySettings

Usage

This gives you another sbt command:

sbt assembly

which produces a "fat jar" (which includes all dependencies, including the Scala libraries).

Now you can start your program

java -cp .../package-assembly.jar

so you only need a Java installation and the "fat jar".