Using reflection to access outer class in Scala

Question

In Scala, is it possible to use reflection to access the outer class of an inner class? For example:

class A { 
   val inner = new { 
      println(getClass.getConstructors.toList)  
      println(getClass.getDeclaredFields.toList)
   }
}

scala> val a = new A
List(public $line11.$read$$iw$$iw$A$$anon$1($line11.$read$$iw$$iw$A))
List()
a: A = A@45f76fc7

I think that the Scala compiler saves a reference to the outer class somewhere, but you can see here that the list of fields printed in the constructor is empty. Also, it looks like the constructor takes a reference to the outer class instance (but it's hard to tell for sure --- I'm not sure exactly what's going on here). I have also noticed in some cases there is an $outer field that seems to be what I need, but it it's not always there, and I don't understand this.

WHY???!!! I have an inner class that I need to create a new instance of using reflection. The new instance is being copied from an existing instance, and needs to have the same outer reference.

Answer 1

I don't think you can reliably get the parent unless you use the parent outside the constructor if the inner class. Given:

class X  {
    val str = "xxyy"
    val self = this

    val inner = new {
        override def toString():String = {
            "inner " + self.toString
        }

    }

    override def toString():String = {
        "ima x" + this.str
    }

}

If you do javap you get a private field $outer

but given:

class X  {
    val str = "xxyy"
    val self = this

    val inner = new {
        println(self)

    }

    override def toString():String = {
        "ima x" + this.str
    }

}

The javap does not indicate the $outer field.