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How does scala.collection.JavaConversions supercede the answers given in Stack Overflow question Iterating over Java collections in Scala (it doesn't work because the "jcl" package is gone) and in Iterating over Map with Scala (it doesn't work for me in a complicated test which I'll try to boil down and post here later).
The latter is actually a Scala Map question, but I think I need to know both answers in order to iterate over a java.util.Map.
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There are generally five ways of iterating over a Map in Java.
A simple for loop that iterates over a collection is translated to a foreach method call on the collection. A for loop with a guard (see Recipe 3.3) is translated to a sequence of a withFilter method call on the collection followed by a foreach call.
In 2.8, you import scala.collection.JavaConversions._ and use as a Scala map. Here's an example (in 2.8.0.RC1):
scala> val jmap:java.util.Map[String,String] = new java.util.HashMap[String,String] jmap: java.util.Map[String,String] = {} scala> jmap.put("Hi","there") res0: String = null scala> jmap.put("So","long") res1: String = null scala> jmap.put("Never","mind") res2: String = null scala> import scala.collection.JavaConversions._ import scala.collection.JavaConversions._ scala> jmap.foreach(kv => println(kv._1 + " -> " + kv._2)) Hi -> there Never -> mind So -> long scala> jmap.keys.map(_.toUpperCase).foreach(println) HI NEVER SO If you specifically want a Scala iterator, use jmap.iterator (after the conversions import).
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