Scala 学习笔记之集合(4)

集合的模式匹配操作：

object CollectionDemo5 {
  def main(args: Array[String]): Unit = {
    //集合模式匹配1
    val ls = List(1, 2, 3, 4, 5)
    println(
      ls match {
        case List(1, 2, 3) => "List(1,2,3)"
        case List(1, 2, 3, 4) => "List(1,2,3,4)"
        case List(1, 2, 3, 4, 5) => "List(1,2,3,4,5)"
        case other => "No match"
      })
    //集合模式匹配2
    val ls2 = List(9, 2, 3, 4, 5, 6)
    println(
      ls2 match {
        case List(1, 2, 3) => "List(1,2,3)"
        case List(1, 2, 3, 4) => "List(1,2,3,4)"
        case List(_, _, 3, 4, x) => "List(1,2,3,4,5)" + x
        case _ => "No match"
      })
    //集合模式匹配3
    val ls3 = List(9, 2, 3, 4, 5, 6)
    println(
      ls3 match {
        case x :: y :: z => z
        case Nil => "No match"
      })
    //集合模式匹配4
    val ls4 = (1, 2, 3, 4, 5, 6)
    println(
      ls4 match {
        case (_,_,x,_,_,_) => x
        case _ => "No match"
      })

  }
}

运行结果：

List(1,2,3,4,5)
No match
List(3, 4, 5, 6)
3