spieden spieden - 9 months ago 71
Java Question

How to create a scala.collection.immutable.Seq from a Java List in Java?

I'm trying to get Akka going in my Java project, and I'm hung up on a small issue with the Seq type(s) from Scala. I'm able to convert my Java List of ActorRef into a scala.collection.Seq, but the Akka API I'm trying to use requires a scala.collection.immutable.Seq. How can I make one?

Code:

static class Router extends UntypedLoadBalancer {
private final InfiniteIterator<ActorRef> workers;

public Router(List<ActorRef> workers) {
Seq workerSeq = asScalaBuffer(workers);

// how to get from the scala.collection.Seq above to the instance of
// scala.collection.immutable.Seq required by CyclicIterator below?
this.workers = new CyclicIterator<ActorRef>();
}

public InfiniteIterator<ActorRef> seq() {
return workers;
}
}

Answer Source

You can use scala.collection.JavaConversions.asScalaBuffer to convert the Java List to a Scala Buffer, which has a toList method, and a Scala List is a collection.immutable.Seq.