Basic operation of Scala collection Map

object MapDemo {

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

    //构建
    val map = mutable.Map[String, Int]("abc" -> 123, ("xyz", 789))
    
    //取值
    if (map.contains("abc")) {
      val v1 = map("abc")
      val v2 = map.get("abc").get
    }
    val v3 = map.getOrElse("abc", 999)

    //添加或更新元素
    map("def") = 456
    map += ("java" -> 20, "scala" -> 30)

    //删除元素
    map -= ("abc", "ooo")

    //四种遍历
    for ((k, v) <- map) println(s"k=${k},v=${v}")
    for (k <- map.keys) println(s"k=${k}")
    for (v <- map.values) println(s"v=${v}")
    for (t <- map) println(s"k=${t._1},v=${t._2}")

    println(map)
  }

}