Simulate input from stdin when running a scala program in intellij

Question

Is there any way to configure the command line args to intellij for stdin redirection?

Something along the lines of:

Run | Edit Run Configurations | Script Parameters

/shared/java/paf-rules.properties 2 < /shared/java/testdata.csv

Answer 1

Unfortunately, no - at least not directly in run configurations.

The best you can do, afaik, is either to:

• modify your script / program to run either with no args (reads System.in) or with a filename argument (reads the file)

• make a wrapper script / program which acts in the manner above.

Hope this helps,

vikingsteve

Answer 2

Here is a template for a solution that has options for:

• stdin
• file
• "heredoc" within the program (most likely useful for testing)

.

  val input = """ Some string for testing ... """

  def main(args: Array[String]) {
    val is = if (args.length >= 1) {
      if (args(0) == "testdata") {
        new StringInputStream(input)
      } else {
        new FileInputStream(args(0))
      }
    } else {
      System.in
    }
    import scala.io._
    Source.fromInputStream(is).getLines.foreach { line =>

This snippet requires use of a StringInputStream - and here it is:

  class StringInputStream(str : String) extends InputStream {
    var ptr = 0
    var len = str.length
    override def read(): Int = {
        if (ptr < len) {
          ptr+=1
          str.charAt(ptr-1)
        } else {
         -1
        }
    }
  }