scala - Spark java.lang.ClassCastException : scala. collection.mutable.WrappedArray$ofRef 无法转换为 java.util.ArrayList

Question

Spark 抛ClassCastExpection对 WrappedArray 执行任何操作时

例子:
我有一个像下面这样的 map 输出

输出:

Map(1 -> WrappedArray(Pan4), 2 -> WrappedArray(Pan15), 3 -> WrappedArray(Pan16, Pan17, Pan18), 4 -> WrappedArray(Pan19, Pan1, Pan2, Pan3, Pan4, Pan5, Pan6))]

当调用 map.values 时，其打印输出如下输出

MapLike(WrappedArray(Pan4), WrappedArray(Pan15), WrappedArray(Pan16, Pan17, Pan18), WrappedArray(Pan19, Pan1, Pan2, Pan3, Pan4, Pan5, Pan6))

如果调用则抛出异常 map.values.map(arr => arr)或 map.values.forEach { value => println(value)}
我无法对包装的数组执行任何操作。我只需要每个wrappedArray 中存在的元素的大小

Error StackTrace
------------------
java.lang.ClassCastException: scala.collection.mutable.WrappedArray$ofRef cannot be cast to java.util.ArrayList
    at WindowTest$CustomMedian$$anonfun$1.apply(WindowTest.scala:176)
    at WindowTest$CustomMedian$$anonfun$1.apply(WindowTest.scala:176)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.immutable.Map$Map4.foreach(Map.scala:181)
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
    at scala.collection.AbstractTraversable.map(Traversable.scala:105)
    at WindowTest$CustomMedian.evaluate(WindowTest.scala:176)
    at org.apache.spark.sql.execution.aggregate.ScalaUDAF.eval(udaf.scala:446)
    at org.apache.spark.sql.execution.aggregate.AggregationIterator$$anonfun$35.apply(AggregationIterator.scala:376)
    at org.apache.spark.sql.execution.aggregate.AggregationIterator$$anonfun$35.apply(AggregationIterator.scala:368)
    at org.apache.spark.sql.execution.aggregate.SortBasedAggregationIterator.next(SortBasedAggregationIterator.scala:154)
    at org.apache.spark.sql.execution.aggregate.SortBasedAggregationIterator.next(SortBasedAggregationIterator.scala:29)
    at scala.collection.Iterator$$anon$14.hasNext(Iterator.scala:389)
    at scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
    at scala.collection.Iterator$$anon$10.hasNext(Iterator.scala:308)
    at scala.collection.Iterator$class.foreach(Iterator.scala:727)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
    at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48)
    at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:103)
    at scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:47)
    at scala.collection.TraversableOnce$class.to(TraversableOnce.scala:273)
    at scala.collection.AbstractIterator.to(Iterator.scala:1157)
    at scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:265)
    at scala.collection.AbstractIterator.toBuffer(Iterator.scala:1157)
    at scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:252)
    at scala.collection.AbstractIterator.toArray(Iterator.scala:1157)
    at org.apache.spark.sql.execution.SparkPlan$$anonfun$5.apply(SparkPlan.scala:212)
    at org.apache.spark.sql.execution.SparkPlan$$anonfun$5.apply(SparkPlan.scala:212)
    at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1858)
    at org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1858)
    at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
    at org.apache.spark.scheduler.Task.run(Task.scala:89)
    at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:227)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

Answer 1

通过转换为 Seq 解决了错误(序列类型)

早些时候:

val bufferMap: Map[Int, util.ArrayList[String]] = buffer.getAs[Map[Int, util.ArrayList[String]]](1)

修改的 :

val bufferMap: Map[Int, Seq[String]] = buffer.getAs[Map[Int, Seq[String]]](1)