objeto 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 para ((k, v) <- mapa) println (s "k = $ {k}, v = $ {v}") para (k <- mapa.claves) println (s "k = $ {k } ") for (v <- map.values) println (s "v = $ {v}") for (t <- map) println (s "k = $ {t._1}, v = $ {t._2} ") println (mapa) } }