The method signature for workWithList looks wrong - where does the ListItemType
type come from? Should this be def workWithList(list: ObservableList[ListItem[_]]) { ...
?
If so, then the problem you will run up against in the match cases is that due to type erasure, the JVM can't tell the difference at runtime between the type signatures of the cases. This can be worked around by, for example, turning the Type1, Type2 and ListItem into case classes (or manually generating unapply methods for them), then deconstructing the item in the match cases, like so:
case class Type1(anInt: Int)
case class Type2(aString: String)
case class ListItem[T](internalValue:T)
object Worker
{
val list1 = FXCollections.observableArrayList[ListItem[Type1]]()
val list2 = FXCollections.observableArrayList[ListItem[Type2]]()
def workWithList(list: ObservableList[ListItem[_]]) {
list.foreach(i => workWithItem(i))
}
def workWithItem(item: ListItem[_]) {
item match {
case ListItem(i: Type1) => println(s"Have type 1: ${i.anInt}") //do something
case ListItem(i: Type2) => println(s"Have type 2: ${i.aString}") //do something else
case anythingElse => println(s"Unknown type: $anythingElse") //just as a safe default for now
}
}
workWithList(list1)
workWithList(list2)
}
Note that I am working here without specific knowledge of the FX libraries (I tried this using straight scala Lists rather than ObservableList
or FXCollections.observableArrayList
), so they may affect the applicability of this solution (and might be where ListItemType
is defined).
The method signature for workWithItem is fine, but the asInstanceOf
cast you tried shouldn't be required.