def main(args: Array[String]): Unit = {
    var sign: Int = 0
    val ch: Char = ‘+‘
    val color = Color.BLACK
    sign = ch match {
      case ‘+‘ => 1
      case ‘-‘ => -1
      case _ => 0
    }
    color match {
      case Color.RED => ;
      case Color.BLACK => ;
      case _ => ;
    }
    println(sign)
  }

obj match {
　　case x: Int => x
　　case s: String => Integer.parseInt(s)
　　case _: BigInt => Int.MaxValue
　　case _ => 0
}

  def main(args: Array[String]): Unit = {
    val arr = Array(0)
    var result = arr match {
      case Array(0) => "0"　　　　　　　//匹配一个包含且只包含0的数组
      case Array(x, y) => x+""+y　　　//匹配任何带有两个元素的数组
      case Array(0, _*) => "0 ..."　　//匹配任何以0开头的数组
      case _=> "something else"
    }
    println(result)
  }

  def main(args: Array[String]): Unit = {
    val lst = List{1,2,3}
    var result = lst match {
      case 0 :: Nil => "0"
      case x :: y :: Nil => x + "" + y
      case 0 :: tail => "0 ..."
      case _ => "something else"
    }
  }

  def main(args: Array[String]): Unit = {
    val pair = Tuple2(0, 2)
    val result = pair match {
      case (0, _) => "0 ..."
      case (y, 0) => y + "0"
      case _ => "neither is 0"
    }
    println(result)
  }

  def main(args: Array[String]): Unit = {
    val result = "-3+4".collect {case ‘-‘ => -1; case ‘+‘ => 1}
    println(result)　　//Vector(-1, 1)
  }