running scala apps with java -jar

Question

I got some problems with the java. Check it out.

sebastian@sebastian-desktop:~/scaaaaaaaaala$ java -cp /home/sebastian/.m2/repository/org/scala-lang/scala-library/2.8.0.RC3/scala-library-2.8.0.RC3.jar:target/scaaaaaaaaala-1.0.jar scaaalaaa.App

Hello World!

That's cool, right, but how bout this:

sebastian@sebastian-desktop:~/scaaaaaaaaala$ java -cp /home/sebastian/.m2/repository/org/scala-lang/scala-library/2.8.0.RC3/scala-library-2.8.0.RC3.jar -jar target/scaaaaaaaaala-1.0.jar

Exception in thread "main" java.lang.NoClassDefFoundError: scala/Application
 at java.lang.ClassLoader.defineClass1(Native Method)
 at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
 at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
 at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
 at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
 at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
 at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
 at scaaalaaa.App.main(App.scala)
Caused by: java.lang.ClassNotFoundException: scala.Application
 at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
 at java.security.AccessController.doPrivileged(Native Method)
 at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
 at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
 ... 13 more

Wat the heck? Any idea why the first works and not the 2nd? How do I -jar my scala??

My thanks in advance, brother.

Michał Kuliński · Accepted Answer · 2015-04-08 15:39:01Z

51

If you define -jar the -classpath is ignored:

Java manual:

-jar When you use this option, the JAR file is the source of all user classes, and other user class path settings are ignored.

You can define the classpath dependencies in the Manifest metadata.

The easiest way to start your app is using the scala scripts:

scala -classpath target/scaaaaaaaaala-1.0.jar scaaalaaa.App Hello World!

edited Apr 8, 2015 at 15:39

Michał Kuliński

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answered May 28, 2010 at 15:18

Thomas Jung

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3 Comments

Thomas Jung Over a year ago

I would prefer a personal Descartes or Newton. :-)

KFL Over a year ago

This is good. But I think the motivation of the question is really, how to deploy and run a Scala app on a machine with only JVM but not Scala or SBT deployed. So it feels like there's no easy way to run it with java. Then my question, alternatively, is if it's easy to deploy scala on the target machine? Accordingly to Scala doc, it recommends running scala app via SBT, not even offering a mention on how to properly install scala by itself. So what's the recommendation here?

Janac Meena Over a year ago

@ThomasJung I don't get the joke, please explain!

hartmut27 · Accepted Answer · 2020-06-05 13:43:09Z

7

use sbt-assembly sbt plugin to produce a jar containing all dependencies

sbt-assembly github

e.g. add a line in project/plugins.sbt:

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.10")

adjust your build.sbt e.g. with

mainClass in (assembly) := Some("mypackage.mysubpackage.MyMainClass")
assemblyJarName in assembly := "my_assembly.jar"

then build your assembled jar with

sbt assembly

and launch it with

java -jar ./target/scala-2.12/my_assembly.jar

Et voilà, no class-path this & thats needed any more. only 1 jar.

edited Jun 5, 2020 at 13:43

answered May 11, 2020 at 19:31

hartmut27

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Comments

hgrey · Accepted Answer · 2016-08-17 19:27:19Z

6

Simply running

scala scaaaaaaaaala-1.0.jar

works for me with 2.11.6

answered Aug 17, 2016 at 19:27

hgrey

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1 Comment

Walker Rowe Over a year ago

that's not the question. of course you can run it with scala. the question is how to run it w/o scala.

Community · Accepted Answer · 2017-05-23 10:30:45Z

4

For an executable jar, the classpath should be in the jar's manifest. For help on doing that, look through the answers to Stackoverflow: How to create an executable jar with dependancy jars.

edited May 23, 2017 at 10:30

CommunityBot

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answered May 28, 2010 at 15:33

Don Roby

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Comments

Nilesh Shinde · Accepted Answer · 2018-10-10 14:01:29Z

0

Below is the way to execute the Scala Executable Jar

We need scala installed in your system.
Here first will give the jar path and jar name
If your code needs any dependency jar then keep all jar in one directory and give a path of this in command like below after the ":".
At last give your class/object name.

scala -cp "/your/jar/path/jar_name.jar:/your/dependency/jar/path/*" SampleCode

answered Oct 10, 2018 at 14:01

Nilesh Shinde

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