Scalaでのパターンマッチング——Optionタイプでのパターンマッチング
2610 ワード
/**
* Option
* Option , Some None( )
* None case object, Some extends Option , Some case class,
* case class , case object ?
* ,case object case class :
* case object CaseObject$.class apply、unapply ,
* None , , case object 。
*/
object OptionDemo {
def main(args: Array[String]): Unit = {
val map = Map("hadoop" -> 1, "spark" -> 2, "flink" -> 3)
//scala
def mapPattern(key: String): Unit = {
//get(key) , key value
map.get(key) match {
case Some(x)=>println(x);x
case None=>println("None");-1
}
}
println(mapPattern("hive"))
println(mapPattern("spark"))
}
}