2018-07-11 リファクタリング

MeatMenu.java

package com.example;

import java.util.Comparator;
import java.util.List;
import java.util.stream.Collectors;

public class MeatMenu {

    private final List<Menu> allMenus;

    public MeatMenu(List<Menu> allMenus) {
        this.allMenus = allMenus;
    }

    private List<Menu> getAllMenus() {
        return allMenus;
    }

    public String createRequestWithAllMeatMenu() {

        return getAllMenus().stream()
                .filter(Menu::hasMeat)
                .map(Menu::getName)
                .collect(Collectors.joining(", "));
    }

    public String createRequestWithMeatMenuFor5000yen() {

        Wallet wallet = new Wallet(5000);

        return getAllMenus().stream()
                // 金額が低いもの順で
                .sorted(Comparator.comparing(Menu::getPriceYen))
                // 肉料理を順番に注文していって、支払い不可能な金額のものは除外
                .filter(Menu::hasMeat)
                .filter(menu -> wallet.pay(menu.getPriceYen())) // Java9以降ならばtakeWhileを使うべき
                .map(Menu::getName)
                .collect(Collectors.joining(", "));
    }

    public static class Wallet {

        private int money;

        public Wallet(int money) {
            this.money = money;
        }

        public boolean pay(int price) {

            if (money < price) {
                // 残高不足
                return false;
            }

            money -= price;
            return true;
        }
    }

    public static class Menu {

        private final String name;
        private final boolean hasMeat;
        private final int priveYen;

        public Menu(String name, boolean hasMeat, int priveYen) {
            super();
            this.name = name;
            this.hasMeat = hasMeat;
            this.priveYen = priveYen;
        }

        public String getName() {
            return name;
        }

        public boolean hasMeat() {
            return hasMeat;
        };

        public int getPriceYen() {
            return priveYen;
        }
    }
}