object Test { def main(args: Array[String]): Unit = { testConversions() testConverters() } def needPackageConcurrentMap(map: collection.concurrent.Map[Int, Int]): Unit = { } def needJavaConcurrent(map: java.util.concurrent.ConcurrentMap[Int, Int]): Unit = { } def testConversions(): Unit = { import collection.JavaConversions._ val skiplist = new java.util.concurrent.ConcurrentSkipListMap[Int, Int] val ctrie = new collection.concurrent.TrieMap[Int, Int] needPackageConcurrentMap(skiplist) needJavaConcurrent(ctrie) } def testConverters(): Unit = { import collection.JavaConverters._ val skiplist = new java.util.concurrent.ConcurrentSkipListMap[Int, Int] val ctrie = new collection.concurrent.TrieMap[Int, Int] needPackageConcurrentMap(skiplist.asScala) needJavaConcurrent(ctrie.asJava) } }