斯卡拉，玩：IntelliJ无法序列化地图[字符串，列表[字符串]]

Question

我有一个Map [String，List [String]]类型的对象。应该很容易序列化。事实上，如果我在项目目录中运行控制台，我可以这样做：

scala> import play.api.libs.json._ 
import play.api.libs.json._  

scala> Json.toJson(Map("ab" -> List("yo", "yo2", "yo3"), "cd" -> List("hi", "hi1", "hi2"))) 
res1: play.api.libs.json.JsValue = {"ab":["yo","yo2","yo3"],"cd":["hi","hi1","hi2"]} 

这很好。但IntelliJ（旗舰版）抱怨

No Json serializer found for type scala.collection.Map[String,List[String]]. Try to implement an implicit Writes or Format for this type. 

即使相同的导入play.api.libs.json._在那里。我很困惑。任何提示？

Answer 1

很蹩脚：问题是scala.collection.Map和scala.Predef.Map（== scala.collection.immutable.Map）之间的（隐藏的）不匹配。我希望它会更加明显。