问题
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.
回答1:
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).
来源：https://stackoverflow.com/questions/2708990/whats-the-new-way-to-iterate-over-a-java-map-in-scala-2-8-0