Outer.java

package example;
public class Outer {
  public class Inner1 {}
  public static class Inner2 {}
}

OuterUser.scala

import example.Outer

object OuterUser {
  def main(args: Array[String]) {
    val a1: Outer = new Outer // OK
    // NG val a2: Outer.Inner1 = new Outer.Inner1
    val a2: Outer#Inner1 = new a1.Inner1
    val a3: Outer.Inner2 = new Outer.Inner2 //OK
    println(a1)
    println(a2)
    println(a3)
  }
}