相关疑难解决方法(0)

我试图将包含Array [String]的列转换为String,但我始终遇到此错误

org.apache.spark.SparkException: Job aborted due to stage failure: Task 0 in stage 78.0 failed 4 times, most recent failure: Lost task 0.3 in stage 78.0 (TID 1691, ip-******): java.lang.ClassCastException: scala.collection.mutable.WrappedArray$ofRef cannot be cast to [Ljava.lang.String; 

这是一段代码

val mkString = udf((arrayCol:Array[String])=>arrayCol.mkString(","))  
val dfWithString=df.select($"arrayCol").withColumn("arrayString",
      mkString($"arrayCol"))