scala sample

CollectionMethods.scala

object CollectionMethods {
  def main(args: Array[String]): Unit = {
    val intList = List(1, 2, 3)
    val intList2 = List(Set(1, 2), Set(3, 4), Set(5, 6))
    val strList = List("Pink", "Blue", "Yellow")
    val mixList = List((1, "Pink"), (2, "Blue"), (3, "Yellow"))
    
    // foreach
    val listA = intList.foreach(f => f * 2)
    println("listA= " + listA)
    strList.foreach(f => println(f))
    
    // map
    val listB = intList.map(f => f * 2)
    println("listB= " + listB)
    
    // collect
    val listC = intList.collect{
      case 1 => "one"
      case 3 => "three"
    }
    println("listC= " + listC)
    
    // flatten
    val listD = intList2.flatten
    println("listD= " + listD)
    
    // unzip
    val listE = mixList.unzip
    println("listE= " + listE)
    
    // zip
    val listF = intList zip strList
    println("listF= " + listF)
    
    // zipWithIndex
    val listG = strList.zipWithIndex
    println("listG= " + listG)
    
    // sorted
    val listH = List(2, 4, 1, 3).sorted
    println("listH= " + listH)
    
    // reverse
    val listI = List(2, 4, 1, 3).reverse
    println("listI= " + listI)
  }
}

PartialFunction.scala

object PartialFunction extends App {
  def matchFunc01: PartialFunction[String, Option[String]] = {
    case "しろ" => Some("ねっけつ")
    case "あお" => Some("はなぞの")
  }

  def matchFunc02: PartialFunction[String, Option[String]] = {
    case "ちゃ" => Some("れいほう")
    case "みどり" => Some("れんごう")
    case _ => None
  }

  // 01 と 02 を合体した関数
  def matchFunc03 = matchFunc01 orElse matchFunc02

  println(matchFunc01("しろ"))
  println(matchFunc02("みどり"))
  println(matchFunc03("ちゃ"))
  println(matchFunc03("むらさき"))
  println(matchFunc01("ちゃ")) // エラーになる
}

PartialFunction2.scala

object NekketuSchool extends App {
  // 普通の関数
  def belongSchool(name: String, schoolName: String): String = {
    name + "は、" + schoolName + "高校の生徒だ！"
  }
  
  println(belongSchool("くにお", "熱血"))
  println(belongSchool("りき", "花園"))
  
  // 関数の部分適用
  val belongSchoolNekketu = belongSchool(_: String, "熱血")
  val belongSchoolHanazono = belongSchool(_: String, "花園")
  val belongSchoolReihou = belongSchool(_: String, "冷峰")
  println(belongSchoolNekketu("すがた"))
  println(belongSchoolHanazono("さおとめ"))
  println(belongSchoolReihou("りゅういち"))
}