list - scala按对象参数错误对列表进行排序

Question

好吧，如果我知道该怎么做，我就不会来找您寻求帮助，无论如何，我的“程序”仍然有问题。

class Mark(val name: String, val style_mark: Double, val other_mark: Double) {}

object Test extends Application
  {
  val m1 = new Mark("Smith", 18, 16);
  val m2 = new Mark("Cole", 14, 7);
  val m3 = new Mark("James", 13, 15);
  val m4 = new Mark("Jones", 14, 16);
  val m5 = new Mark("Richardson", 20, 19);
  val m6 = new Mark("James", 4, 18);

  val marks = List[Mark](m1, m2, m3, m4, m5, m6);

  def avg(xs: List[Double]) = xs.sum / xs.length

  val marksGrouped = marks.groupBy(_.name).map { kv => new Mark(kv._1, avg(kv._2.map(_.style_mark)), avg(kv._2.map(_.other_mark))) }

  val marksSorted = marksGrouped.sortWith((m1, m2) => m1._style_mark < m2._style_mark)

  }

这是我得到的错误:error: value sortWith is not member of scala.collection.immutable.Iterable[Mark]

Answer 1

您必须先在 marksGrouped 上调用 toList。 Iterable 没有 sortWith 方法，但 List 有。