Question

In below class is my main method not defined correctly ? When I try to run it from Eclipse I dont have the option to run it as a scala program. When I remove filesEnding(".txt") I can then run the program.

object FileMatcher {

  private def filesHere = (new java.io.File(".")).listFiles()

  private def filesMatching(matcher: String => Boolean) = 
    for(file <- filesHere; if matcher(file.getName))
        yield file

  def filesEnding(query: String) = filesMatching(_.endsWith(query))

  def main(args:Array[String]) = {
      filesEnding(".txt")
  }

}

Answer 1

Main must return type Unit. But filesEnding does not return Unit, it returns files. The easiest fix is to remove the = so the return value from the method defaults to Unit.

def main(args: Array[String]) {
// ...
}