模式匹配

package com.zy.scala

import scala.util.Random

/**
  * 模式匹配
  */
object CaseDemo {
  def main(args: Array[String]): Unit = {
    //匹配字串
    val arr1 = Array(" hadoop", " zookeeper", " spark ")
    val name = arr1(Random.nextInt(arr1.length))
    name match {
      case " hadoop " => println(" 大資料分散式儲存和計算框架 ...")
      
 
case " zookeeper " => println(" 大資料分散式協調服務框架 ...")
      case " spark " => println(" 大資料分散式記憶體計算框架 ...")
      case _ => println("  我不認識你 ...")
    }

    //匹配資料型別
    val arr2 = Array("hello", 1, 2.0, CaseDemo)
    val v = arr2(Random.nextInt(4))
    println(v)
    v match {
      case
 
 x: Int => println("Int " + x)
      case y: Double if (y >= 0) => println("Double " + y)
      case z: String => println("String " + z)
      case _ => throw new Exception("not match exception")
    }

    //匹配陣列
    val arr = Array(1, 3, 5)
    arr match {
      case Array(1, x, y) => println(x + " " + y)
      
 
case Array(0) => println("only 0")
      case Array(0, _*) => println("0 ...")
      case _ => println("something else")
    }

    //匹配集合
    val lst = List(3, -1)
    lst match {
      case 0 :: Nil => println("only 0")
      case x :: y :: Nil => println(s"x: $x y:$y")
      case 0 :: tail => println("0 ...")
      case _ => println("something else")
    }

    //匹配元組
    val tup = (1, 3, 7)
    tup match {
      case (1, x, y) => println(s"1, $x , $y")
      case (_, z, 5) => println(z)
      case _ => println("else")
    }

    /**
      * 注意：在 Scala 中列表要麼為空（Nil 表示空列表）要麼是一個 head 元素加上一個 tail 列表。
      * 9 :: List(5, 2) :: 操作符是將給定的頭和尾建立一個新的列表
      * 注意：:: 操作符是右結合的，如 9 :: 5 :: 2 :: Nil 相當於 9 :: (5 :: (2 :: Nil))
      */
  }
}

樣例類的模式匹配

package com.zy.scala

import scala.util.Random

//樣例類
case class SubmitTask(id: String, name: String)

case class HeartBeat(time: Long)

case object CheckTimeOutTask

object CaseClsDemo {
  def main(args: Array[String]): Unit = {

    //模式匹配 樣例類
    val arr = Array(CheckTimeOutTask, HeartBeat(12333), SubmitTask("0001", "task- - 0001"))
    arr(Random.nextInt(arr.length)) match {
      case SubmitTask(id, name) => {
        println(s" $id , $name")
      }
      case HeartBeat(time) => {
        println(time)
      }
      case CheckTimeOutTask => {
        println("check")
      }
    }
  }
}