如何从 Java 中的 Java 列表创建 scala.collection.immutable.Seq？

Question

我试图让 Akka 进入我的 Java 项目，但我对来自 Scala 的 Seq 类型的一个小问题感到困惑。 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. 我怎样才能做一个？

代码：

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 1

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 .

Answer 2

路由器的 akka Java 文档以及 CyclicIterator 的ScalaDoc都建议 CyclicIterator 构造函数采用 List。

Answer 3

您可以使用：

scala.collection.JavaConverters.collectionAsScalaIterableConverter(workers).asScala().toSeq()

Answer 4

你可以试试这个：

scala.collection.JavaConverters.asScalaIteratorConverter(list.iterator()).asScala().toSeq();