Dstream火花流

Question

你好，我写了下面的代码

val receivedStream: DStream[PubsubSparkMessage] =
      PubsubSource.createStream(ssc, pubsubConfig, pubsubSubscriber)
    @volatile var receivedMessages: List[PubsubSparkMessage] = List() //scalastyle:ignore
    receivedStream.foreachRDD { rdd =>
      if (!rdd.isEmpty()) {
        receivedMessages = List(rdd.collect)
        receivedMessages
      }
    }

由于类型不匹配，我得到了一个错误；我的问题是如何将List[ArrayPubsubSparkMessage]修改为ListPubsubSparkMessage

Answer 1

类似于：

val list : List[Array[PubsubSparkMessage]] = List()

val result = list.flatMap(x => x)