sbt run is not picking up mainClass from build.sbt

Question

We are unable to run a mainclass . We are using sbt 13.2 against scala 2.9.3

Here is the entry in build.sbt:

mainClass in (Compile,run) := Some("com.mycompany.swlab.sparkpoc.sql.DbPing")

Let's do an "sbt run":

C:\apps\simplews>sbt run
"sbt13"
Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true
[info] Loading project definition from C:\apps\simplews\project
[info] Set current project to websocket-simple (in build file:/C:/apps/simplews/)
java.lang.RuntimeException: No main class detected.
        at scala.sys.package$.error(package.scala:27)

Here is the source file. Notice it is an object with main() method. So we should be able to execute it.

package com.mycompany.swlab.sparkpoc.sql

import org.apache.log4j.Logger

object DbPing {
  import java.sql.{DriverManager, Connection}


  def main(args: Array[String]) {

I have also tried to provide specific class to run as follows:

> run com.mycompany.swlab.sparkpoc.sql.DB org.apache.hadoop.hive.jdbc.HiveDriver jdbc:hive://localhost:10000/default "" ""

Here is the full output

Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true
[info] Loading project definition from C:\apps\simplews\project
[info] Set current project to websocket-simple (in build file:/C:/apps/simplews/)
> run com.mycompany.swlab.sparkpoc.sql.DB org.apache.hadoop.hive.jdbc.HiveDriver jdbc:hive://localhost:10000/default "" ""
java.lang.RuntimeException: No main class detected.
        at scala.sys.package$.error(package.scala:27)
[trace] Stack trace suppressed: run last root/*:run for the full output.
[error] (root/*:run) No main class detected.
[error] Total time: 0 s, completed May 27, 2014 9:13:55 PM

Answer 1

The issue was with a corrupted project/Build.scala. I reverted to a simple build.sbt and that resolved this issue.