Java Collection to Traversable

chapter4_4.sc

import java.util
import java.util.{Collection => JCollection, ArrayList}

class JavaToTraversable[E] (javaCollection: JCollection[E]) extends Traversable[E] {
  override def foreach[U](f: (E) => U): Unit = {
    val iterator = javaCollection.iterator()
    while(iterator.hasNext) {
      f(iterator.next())
    }
  }
}

val jColl = new util.ArrayList[Int]()
(1 to 5) foreach {jColl.add(_)}

val javaToTraversable = new JavaToTraversable(jColl)
javaToTraversable map {_ * 10} filter {_ > 20}