Scala: Converting Java collections into their Scala counterparts

In the scala.collection.jcl library, you'll find Scala wrappers, adding Scala methods to Java collections. This means that a Java collection (e.g., an ArrayList) will be converted to work as a Scala collection, making it possible to call foreach on a ArrayList, etc:

import scala.collection.jcl.Conversions._

val a = new java.util.ArrayList[String]
a.add("Asa")
a.add("nisi")
a.add("masa")

// foreach now works on a Java List:
a.foreach(println)

Simlarily, you can now call .mkString on a Java list:

// Let's use mkString to print the
// ListArray contents as a Prolog spell/3 fact:

println(a.mkString("spell('", "', '", "')."))

// -> spell('Asa', 'nisi', 'masa').

See this Scala mailing list thread.