在Spark的Scala REPL中使用：load时找不到值

Question

任何关于Spark的REPL(Spark 2.0.0(会抛出以下错误的想法：

scala> :load ../StatsWithMissing.scala
Loading ../StatsWithMissing.scala...
import org.apache.spark.util.StatCounter
defined class NAStatCounter
<console>:22: error: illegal start of statement (no modifiers allowed here)
   override def toString: String =
   ^
<console>:26: error: not found: value stats
           "stats " + stats.toString + "NaN " + missing
<console>:26: error: not found: value missing
       "stats " + stats.toString + "NaN " + missing
<console>:1: error: eof expected but '}' found.
}
^
defined object NAStatCounter
warning: previously defined class NAStatCounter is not a companion to object     NAStatCounter.
Companions must be defined together; you may wish to use :paste mode for this.
<console>:27: error: value add is not a member of NAStatCounter
     def apply(x: Double) = new NAStatCounter().add(x)

加载以下文件时：

import org.apache.spark.util.StatCounter
class NAStatCounter extends Serializable 
{
  val stats: StatCounter = new StatCounter()
  var missing: Long = 0
  def add(x: Double): NAStatCounter = 
  {
    if (java.lang.Double.isNaN(x))
      missing += 1
    else
      stats.merge(x)
    this
  }
  def merge(other: NAStatCounter): NAStatCounter =
  {
    stats.merge(other.stats)
    missing += other.missing
    this
  }
  override def toString: String = 
  {
    "stats " + stats.toString + "NaN " + missing
  }
}
object NAStatCounter extends Serializable 
{
  def apply(x: Double) = new NAStatCounter().add(x)
}

使用:Load ../StatsWithMissing.scala不会产生任何错误，但当尝试创建NAStatCounter时，我会得到以下错误：

scala> :paste ../StatsWithMissing.scala
Pasting file ../StatsWithMissing.scala...
import org.apache.spark.util.StatCounter
defined class NAStatCounter
defined object NAStatCounter
scala> val nas1 = NAStatCounter(10.0)
<console>:28: error: reference to NAStatCounter is ambiguous;
it is imported twice in the same scope by
import $line48$read.NAStatCounter
and import INSTANCE.NAStatCounter
       val nas1 = NAStatCounter(10.0)
                  ^

Answer 1

您没有使用K&R大括号，并且由于repl逐行解释，所以左大括号不是类的主体。

尝试class NAStatCounter {，即大括号在同一行上。

否则，class C本身就是一个完整的定义。