CODEWITHSUNDEEP
scalascala-collections
JSF Learner
JSF Learner

Reputation: 183

scala.Some cannot be cast to scala.collection.immutable.Map Exception

I'm new to scala,

val data = Map("test" -> data1, 
               "cat" -> None, 
               "myList" -> Map("test2" -> data2, "test3" -> data3))

val output = data.map(x => 
      if (x._2.isInstanceOf[Map[String, Any]]) (x._1 -> Some(x._2)) 
      else x)

Map(test -> data1, 
    cat -> None, 
    myList -> Some(Map(test2 -> data2, test3 -> data3)))

val valueToFieldMapping = output(fieldName).get.asInstanceOf[Map[String, String]]

I'm getting 

java.lang.ClassCastException: scala.Some cannot be cast to scala.collection.immutable.Map

exception please help me if anyone has an idea about this. Thanks

Upvotes: 2

Views: 13036

Answers (2)

Tim
Tim

Reputation: 27356

Firstly, let's clean up the definition of output by using mapValues:

val output = data.mapValues(x =>
  if (x.isInstanceOf[Map[String, Any]]) Some(x)
  else x)

Then do this

val valueToFieldMapping = output(fieldName).asInstanceOf[Option[Map[String, String]]].get

You can't call get on the Some you generate when creating output because the compile doesn't know it is an Option yet.

Having said all that, the comments are right in saying that using Any and asInstanceOf is really ugly so you need to find a better way of expressing whatever it is you are trying to do. At the very least, use match rather than asInstanceOf so that you can implement the error case if the object is not what you think it is.

Upvotes: 1

Raman Mishra
Raman Mishra

Reputation: 2686

The problem is with this line you don't have .get property on instance of Object. you don't need .get if you want to use .get method then do output.get(fieldName)

val valueToFieldMapping = output(fieldName).get.asInstanceOf[Map[String, String]]

output.get(fieldName) gives you the Option[Object] and you are trying to convert object into the instance of the Map[String, String]

there is no implicit conversion from Option to map so that's the reason you are getting the error:

java.lang.ClassCastException: scala.Some cannot be cast to scala.collection.immutable.Map

or you can do like this:

val valueToFieldMapping: Option[Map[String, String]] = output.get(fieldName).asInstanceOf[Option[Map[String, String]]]

Upvotes: 1

Related Questions