从包含两个参数 notional 和 currency 的对象列表开始,如何汇总每种货币的总名义值?
鉴于:
case class Trade(name: String, amount: Int, currency: String)
val trades = List(
Trade("T150310", 10000000, "GBP"),
Trade("T150311", 10000000, "JPY"),
Trade("T150312", 10000000, "USD"),
Trade("T150313", 100, "JPY"),
Trade("T150314", 1000, "GBP"),
Trade("T150315", 10000, "USD")
)
我怎样才能得到:
Map(JPY -> 10000100, USD -> 10010000, GBP -> 10001000)