the abstract class can not be write in List[T]

e.scala

I'm reading the IBM developer scala guide
http://www.ibm.com/developerworks/cn/java/j-scala05059.html

and write the weatherReport copy form example

WeatherReport.scala 


import org.apache.http.impl.client.DefaultHttpClient
import org.apache.http.HttpResponse
import org.apache.http.util.EntityUtils


object WeatherTest {
  def main(args: Array[String]) = {
    new WeatherTest().callTwitterTest
  }
}


class WeatherTest {


  import org.apache.http.client._, methods._


  def callTwitterTest = {
    val testURL = "http://www.google.com/ig/api?weather=Beijing"

    // HttpClient API 4
    val client: HttpClient = new DefaultHttpClient()
    val method: HttpUriRequest = new HttpGet(testURL)

    val response: HttpResponse = client.execute(method)
    val responseString: String = EntityUtils.toString(response.getEntity)
    val c = xml.XML.loadString(responseString)
    val forecastConditionsList = new List[forecastConditions]


    for (n <- (c \\ "forecast_conditions").elements)
      forecastConditionsList += (forecastConditions.fromXml(n))

    forecastConditionsList.forall(x -> println(x.toString()))
  }

}

WeatherType.scala


abstract class forecastConditions {
  val dayOfWeek: String
  val lowTemperature: String
  val highTemperature: String
  val iconUrl: String
  val condition: String

}

object forecastConditions {
  /*
  <forecast_conditions>
<day_of_week data="Fri"/>
<low data="64"/>
<high data="82"/>
<icon data="/ig/images/weather/mostly_sunny.gif"/>
<condition data="Mostly Sunny"/>
</forecast_conditions>
         */
  def formXml(node: scala.xml.Node): forecastConditions = {
    new forecastConditions {
      val dayOfWeek = (node \\ "day_of_week").text
      val lowTemperature = (node \\ "low").text
      val highTemperature = (node \\ "high").text
      val iconUrl = (node \\ "icon").text
      val condition = (node \\ "condition").text

      override def toString():String = {
         dayOfWeek+" "+ lowTemperature+" "+highTemperature+" "+iconUrl+" "+ condition
      }
    }

  }
}


the compile show
error: class List is abstract; cannot be instantiated
val forecastConditionsList =new  List[forecastConditions]

val a=<a>
<forecast_conditions>
    <day_of_week data="Wed"></day_of_week>
</forecast_conditions>
<forecast_conditions>
    <day_of_week data="Thu"></day_of_week>
</forecast_conditions>
<forecast_conditions>
    <day_of_week data="Fri"></day_of_week>
</forecast_conditions>
<forecast_conditions>
    <day_of_week data="Sat"></day_of_week>
</forecast_conditions>
<a>
val forecast= a\\ "forcast_conditions"
接下来怎么对forecast 中每一个取出来啊。。
我看forecast.elements方法被标注为过时了

我建议你看看program in scala先。

val forecastConditionsList:List[forecastConditions] = List.empty