learn_tmp

// 4.1构造映射
val scores = Map("Alice" -> 10, "Bob" -> 3, "Cindy" -> 8) // 不可更改值
val scoresMu = scala.collection.mutable.Map("Alice" -> 10, "Bob" -> 3, "Cindy" -> 8) // 可修改值
val scores2 = Map(("Alice", 10), ("Bob", 3), ("Cindy", 8))

// 4.2 获取映射中的值
val bobsScore = scores("Bob") // 如果映射不包含Bob键，则会抛出报错
val bobsScore2 = if (scores.contains("Bob")) scores("bob") else 0 // 先判断再返回
val bobsScore3 = scores.getOrElse("Bob",0) // 如果映射包含键"Bob"，返回对应的值；否则返回0


https://blog.csdn.net/ajian005/article/details/51206976