When are singleton objects built?

The code will be called when O

opened for the first time (some method or some property). For example, the following program

object O {
  println("Hello from O")
  def doSome() {}
}

object App extends Application {
  println("Before O")
  O.doSome()
  println("After O")
}

      

        
        
        
      

    

will give

Before O
Hello From O
After O

      

        
        
        
      

    

It is not easy enough to define O

. Also the call won't work Class.forName("O")

as the name of the compiled object O$

, so call Class.forName("O$")

.