问为什么我在ScalaIDE中运行代码时会得到`java.lang.NoClassDefoundError：Scala/Function1‘？

public static void main(String args[]) {
  java.util.Map<String, java.util.List<String>> rec = news.recommend.DriverObj.runTest();     
  System.out.println(rec.toString());
}

def runTest: java.util.Map[String, java.util.List[String]] = {
  new java.util.HashMap[String, java.util.List[String]]
}

Exception in thread "main" java.lang.NoClassDefFoundError: scala/Function1
    at news.recommend.DriverObj.runTest(DriverObj.scala)