我正在Scala中进行一次培训练习并获取此val重新分配错误。我没有看到我的重新分配新值VAL重新分配到Scala中的val
class personTest
{
val alf = Person("Alf", 30, List(EmailAddress("[email protected]")))
val fredrik = Person("Fredrik", 33, List(EmailAddress("[email protected]"), EmailAddress("[email protected]")))
val johannes = Person("Johannes", 0, Nil)
val persons = List(alf, fredrik, johannes)
@Test
def testNameToEmailAddress
{
// Create a map from each persons name to their e-mail addresses,
// filtering out persons without e-mail addresses
// Hint: First filter list, then use foldLeft to accumulate...
val emptyMap: Map[String, List[EmailAddress]] = Map()
val nameToEmail = persons.filter(_.emailAddresses.length>0).foldLeft(emptyMap)((b,p)=> b+=p.name->p.emailAddresses)
assertEquals(Map(alf.name -> alf.emailAddresses, fredrik.name -> fredrik.emailAddresses), nameToEmail)
}
}
,我得到这个错误
error: reassignment to val
val nameToEmail = persons.filter(_.emailAddresses.length>0).foldLeft(emptyMap)((b,p)=> b+=p.name->p.emailAddresses)
谢谢你,工作太,我没有使用可变地图 – 2010-10-11 18:50:38