178日目

日記

今日はカレー

今日書いたコード

class Order(val orderNumber: Int) {
   private val itemList = mutableListOf<Item>()

   fun addItem(newItem: Item) {
       addAll(listOf(newItem))
   }

   fun addAll(newItems: List<Item>) {
       itemList.addAll(newItems)
   }

    fun print() {
        println("Order #${orderNumber}")
        var total = 0
        for (item in itemList) {
            println("${item}: $${item.price}")
            total += item.price
        }
        println("Total: $${total}")
    }
}

open class Item(val name: String, val price: Int)

class Noodles : Item("Noodles", 10) {
    override fun toString(): String {
        return name
    }
}

class Vegetables(vararg val toppings: String) : Item("Vegetables", 5) {
    override fun toString(): String {
        if (toppings.isEmpty()) {
            return "$name Chef's Choice"
        }
        
        return name + " " + toppings.joinToString()
    }
}

fun main() {
    val order1 = Order(1)
    order1.addItem(Noodles())
    order1.print()

    println()

    val order2 = Order(2)
    order2.addItem(Noodles())
    order2.addItem(Vegetables())
    order2.print()

    println()

    val order3 = Order(3)
    val items = listOf(Noodles(), Vegetables("Carrots", "Beans", "Celery"))
    order3.addAll(items)
    order3.print()
}

Order #1
Noodles: $10
Total: $10

Order #2
Noodles: $10
Vegetables Chef's Choice: $5
Total: $15

Order #3
Noodles: $10
Vegetables Carrots, Beans, Celery: $5
Total: $15

感想

ArrayとListは違うものらしい．Arrayのサイズは固定でListのは可変．

an array's size is defined upon initialization and is never changed; in turn, a list doesn't have a predefined size https://kotlinlang.org/docs/collections-overview.html#set