Scala - Main (Top-Level Objects)

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In Scala, the main or entry point method is defined in an object.

An object can be made executable by either:

adding extending the type App
or by adding a method def main(args: Array[String])

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Two way

App

object HelloWorld extends App {
  println("Hello, World!")
}

If that object extends trait App, then all statements contained in that object will be executed. otherwise you have to add a method main which will act as the entry point of your program.

Main

object HelloWorld {
  def main(args: Array[String]) {
    println("Hello, World!")
  }
}