Scala使用Scala枚举在一周中的几天
示例
可以通过扩展Enumeration创建类似Java的枚举。
object WeekDays extends Enumeration {
val Mon, Tue, Wed, Thu, Fri, Sat, Sun = Value
}
def isWeekend(day: WeekDays.Value): Boolean = day match {
caseWeekDays.Sat|WeekDays.Sun=> true
case _ => false
}
isWeekend(WeekDays.Sun)
res0: Boolean = true还可以为枚举中的值添加易于理解的名称：
object WeekDays extends Enumeration {
val Mon = Value("Monday")
val Tue = Value("Tuesday")
val Wed = Value("Wednesday")
val Thu = Value("Thursday")
val Fri = Value("Friday")
val Sat = Value("Saturday")
val Sun = Value("Sunday")
}
println(WeekDays.Mon)
>> Monday
WeekDays.withName("Monday") == WeekDays.Mon
>> res0: Boolean = true当心不太安全的行为，其中不同的枚举可以评估为相同的实例类型：
object Parity extends Enumeration {
val Even, Odd = Value
}
WeekDays.Mon.isInstanceOf[Parity.Value]
>> res1: Boolean = true