java generics List elements are not ActorRef

Asked Dec 27 '17 at 15:34

Active Dec 27 '17 at 16:20

Viewed 72 times

I have defined a list of subscribers

public class PropertyHandlerInfo<T> {
...
    public final List<ActorRef> subscribers = new ArrayList<>();
...
}

when I want to retrieve an element of list I get an Object type not a ActorRef.

PropertyHandlerInfo propertyHandlerInfo = new PropertyHandlerInfo();
...
ActorRef o = propertyHandlerInfo.subscribers.get(0);

I get the floowing error:

Error:(34, 61) java: incompatible types: java.lang.Object cannot be converted to akka.actor.ActorRef

What can be the problem?

UPDATE:

This question asks a practical problem, some people showed me a similar theoretical question:

I can extrapolate the answer to this question from that link.

The most helpful comment was for me: "Using a raw type erases ALL generics in that class." by Jorn Vernee

edited Dec 27 '17 at 16:20

asked Dec 27 '17 at 15:34

Dániel Kis

1

See: https://stackoverflow.com/questions/2770321 – Jorn Vernee Dec 27 '17 at 15:43
@azurefrog: same here. – Hovercraft Full Of Eels Dec 27 '17 at 15:46
7

There are many dupes of this, so I'll say it here: Using a raw type erases _ALL_ generics in that class. – Jorn Vernee Dec 27 '17 at 15:46
That's it, what @JornVernee states. – Hovercraft Full Of Eels Dec 27 '17 at 15:47
3

This answer says what happens: [link](https://stackoverflow.com/a/47626695/7470253). Basically, since your type is generic and you ignored generic types on it, Java compiler chooses to wipe **all** generics-related information from your type-use. – M. Prokhorov Dec 27 '17 at 15:48
@JornVernee: Thanks it is the solution. – Dániel Kis Dec 27 '17 at 15:58

0 Answers0