Can't figure out how to specify a main class.

[hartleys]

I'm sure I must be doing something wrong, but I can't for the life of me figure out what. I've stripped it down to as simple as possible, but it still doesn't work.

I keep getting this error when I try to run the jar files:

Error: Could not find or load main class runner.runner

The build.sbt and plugins.sbt files were exactly as in your example at:
https://github.com/sbt/sbt-assembly
except build.sbt is:

import AssemblyKeys._
assemblySettings
jarName in assembly := "MyScalaUtils.jar"
mainClass in assembly := Some("runner.runner")

Here's my src directory layout:

$ ls -R src
src:
helloWorldTest  runner

src/helloWorldTest:
helloWorld.scala

src/runner:
runner.scala

runner.scala is just:

package runner

class runner {
  def main(args: Array[String]){
    println("Starting run.");
    helloWorldTest.helloWorld.run(args);
    println("Done.");
  }
}

What the heck is going wrong here?

[eed3si9n]

Try putting your sources under src/main/scala/.

[hartleys]

That worked. Sorry for the trouble!

PS. For anyone else having this problem and/or attempting to replicate. The package runner also has to be changed to:

package runner
object runner {
  def main(args: Array[String]){
    println("Starting run.");
    helloWorldTest.helloWorld.run(args);
    println("Done.");
  }
}

[robinloxley1]

I have same problem. I am running for java, and I put my code under src/main/java//. I can see the Main-Class entry has been written into META-INF/MANIFEST.MF. But it still complains by not finding main class. I can do java -cp however.

[yishenggudou]

I Got this error too

[kindlychung]

Same issue here.

java -jar complains about main class not found, java -cp x.jar path.to.Main works.

[nob13]

Same issue here.

java -jar complains about main class not found, java -cp x.jar path.to.Main works.

For google: Perhaps it's a problem like this: https://stackoverflow.com/a/46287790