java.lang.NoSuchMethodError: scala.Predef$.refArrayOps

Question

I have the following class:

import scala.util.{Success, Failure, Try}


class MyClass {

  def openFile(fileName: String): Try[String]  = {
    Failure( new          


        

Answer 1

In my experience, if you still get errors after matching scalatest version and scala version in build.sbt, you have to think about your actual scala version that is running on your machine. You can check it by $ scala, seeing

Welcome to Scala 2.12.1 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_121). Type in expressions for evaluation. Or try :help. this type of messages. You need to match this Scala version(eg. 2.12.1 here) and build.sbt's one.

Answer 2

In my case, I had a project jar dependency which was depending on a different version of scala. This was found under Project Structure -> Modules -> (selected project) -> Dependencies tab. Everything else in the project and its libraries lined up in scala version (2.12), but the other jar was hiding a transitive dependency on an older version (2.11).

Answer 3

in eclipse ide the project tends to be preselected with the scala installation 'Latest 2.12 bundle (dynamic)' configuration. If you are not actually using 2.12 for your Scala project and you attempt to run your project through the IDE, then this issue will manifest itself.

I've also noticed if I rebuild my eclipse project with the sbt command: "eclipse with-source" that this has the side effect of resetting the eclipse project scala installation back to the 2.12 setting (even though my build.sbt file is configured for a 2.11 version of Scala). So be on the lookout for both of those scenarios.

Answer 4

scalatest_2.11 is the version of ScalaTest compatible only with Scala 2.11.x. Write libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.0" % "test" (note %%) instead to pick the correct version automatically and switch to Scala 2.11.8 until scalatest_2.12 is released (it should be very soon). See http://www.scala-sbt.org/0.13/docs/Cross-Build.html for more.