Access private fields and methods using Java Reflection in Scala.

AccessGranted.scala

object Main extends App {

  val printer = new Printer[String]()
  val break = true
  val text = "access granted"
    
  //cannot be accessed:
  //printer.printCodeName
  //printer.codeName = "Rejewski"
  //printer.printCodeName
  //printer.printItem(text, break)
  
  val printerClass = classOf[Printer[String]]
  
  val method1 = printerClass.getDeclaredMethod("printCodeName") // no parameters
  method1.setAccessible(true)
  method1.invoke(printer)
  
  val field = printerClass.getDeclaredField("codeName")
  field.setAccessible(true)
  field.set(printer, "Rejewski")
  
  method1.invoke(printer)
  
  val method2 = printerClass.getDeclaredMethod("printItem", classOf[Object], classOf[Boolean]) // Type T is object
  method2.setAccessible(true)
  method2.invoke(printer, text.asInstanceOf[Object], break.asInstanceOf[Object])
  
  //output:
  //Scherbius
  //Rejewski
  //access granted
  
}

class Printer[T] {
  
  private[this] var codeName = "Scherbius"
  
  private def printCodeName = println(codeName)
    
  protected def printItem(item: T, break: Boolean) = if (break) println(item) else print(item) 
  
}