dataFrame把某列类型为array<double>或者array<string>数组里的值为null的置换为非null

----把array<double>里的null值转换为0：

df.withColumn("Value", replaceArrayNullToZeroUDF(col("Value")))

def replaceArrayNullToNOVALUEUDF = udf(replaceArrayNullToNOVALUE)

def replaceArrayNullToZero: (List[String] => List[String]) = {
  s =>
    s match {
      case null => List()
      case ::(head, next) =>
        s.map(item => {
          val value = item match {
            case null => "0"
            case "" => "0"
            case "null" => "0"
            case _ => item
          }
          value
        })
    }
}

----把array<string>里的null值转换为字符串NOVALUE：

def replaceArrayNullToNOVALUE: (List[String] => List[String]) = {
  s =>
    s match {
      case null => List()
      case _ => s.map(item => {
        val value = item match {
          case null => "NOVALUE"
          case "" => "NOVALUE"
          case "null" => "NOVALUE"
          case _ => item
        }
        value
      })
    }

}