November 2022
Beginner to intermediate
544 pages
12h 39m
Korean
Content preview from 자바에서 코틀린으로
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292
자바에서 코틀린으로
예제
14.28
[
accumulator
.
16
:
src
/
main
/
java
/
travelator
/
itinerary
/
PricingContext
.
kt
]
class PricingContext(
private val userCurrency: Currency,
private val exchangeRates: ExchangeRates
) {
fun toUserCurrency(money: Money) =
exchangeRates.convert(money, userCurrency)
fun summarise(costs: Iterable<Money>): CostSummary {
val currencyTotals: List<Money> = costs
.groupBy { it.currency }
.values
.map {
it.sumOrNull() ?: error(“Unexpected empty list”)
}
val lines: List<CurrencyConversion> = currencyTotals
.sortedBy { it.currency.currencyCode }
.map(::toUserCurrency)
val total = lines
.map { it.toMoney }
.sum(userCurrency)