Question

当初始化类的实例时，使用随播对象在REPL（spark-shell 2.1.0）中抛出模糊引用错误（1.x.x中的问题4165已关闭）。我在Spark 2.1.0中看到了这个错误（见下文）。

scala> :pas
// Entering paste mode (ctrl-D to finish)

class X {
  var m : Long =0
  def add(x: Long): X = {
    m += x
    this 
  }
}
object X {
  def apply(x:Long) = new X().add(x)
}

// Exiting paste mode, now interpreting.

defined class X
defined object X

scala> val v = X(2)
<console>:26: error: reference to X is ambiguous;
it is imported twice in the same scope by
import $line14$read.X
and import INSTANCE.X
       val v = X(2)
               ^

我错过了什么吗？感谢

Answer 1

您无法在shell中定义这样的伴随对象。你需要一个对象包装器

object myWrapper {
  class X {
    var m: Long = 0
    def add(x: Long): X = {
      m += x
      this 
    }
  }

  object X {
    def apply(x:Long) = new X().add(x)
  }
}

import myWrapper._

使用伴随对象实例化一个类

1 个答案: