如何從 Java 中的 Java 列表創建 scala.collection.immutable.Seq？

Question

我試圖讓 Akka 進入我的 Java 項目，但我對來自 Scala 的 Seq 類型的一個小問題感到困惑。 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. 我怎樣才能做一個？

代碼：

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 文檔以及 CyclicIterator 的ScalaDoc都建議 CyclicIterator 構造函數采用 List。

Answer 3

您可以使用：

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

Answer 4

你可以試試這個：

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