scala继承例子1

import scala.collection.mutable.ArrayBufferobject Demo3 extends App {  abstract class Item {    def price: Double    def description: String  }  class SimpleItem(val price: Double, val description: String) extends Item  class Bundle extends Item {    private var items = ArrayBuffer[Item]()    def price = items.foldLeft(0.0)(_ + _.price)    override def description = {      items.map(_.description).mkString(",")    }    def addItem(item: Item): Unit = {      items += item    }  }  val item1 = new SimpleItem(4.5, "a");  val item2 = new SimpleItem(4.5, "b");  val item3 = new SimpleItem(3.5, "c");  val b = new Bundle  b.addItem(item1)  b.addItem(item2)  b.addItem(item3)  println(b.price)  println(b.description)}