相关疑难解决方法(0)

在https://try.kotlinlang.org/#/Kotlin%20Koans/Collections/FlatMap/Task.kt

它有使用flatMap和的样本map

似乎两者都在做同样的事情,是否有一个样本来显示使用flatMap和map？的区别？

数据类型:

data class Shop(val name: String, val customers: List<Customer>)

data class Customer(val name: String, val city: City, val orders: List<Order>) {
    override fun toString() = "$name from ${city.name}"
}

data class Order(val products: List<Product>, val isDelivered: Boolean)

data class Product(val name: String, val price: Double) {
    override fun toString() = "'$name' for $price"
}

data class City(val name: String) {
    override fun toString() = name
}

样品:

fun Shop.getCitiesCustomersAreFrom(): …