如何从 ArrayList 中删除索引并打印已删除索引的总整数？

Question

我想做一个仓库的程序。 emptyStock() 方法应该从列表中删除已售出的食物。 print() 方法应该打印所有食品清单和已售出的总食品（公斤）。

public class Lists {
private String name;
private String category;
private int amount;

public Lists(String name, String category, int amount) {
   this.name = name;
   this.category = category;
   this.amount = amount;
}

public String toString() {
    return name + " is " + category + " and we have " + amount + " in warehouse";
}
}

public class Food {
ArrayList<Lists> Food = new ArrayList<>();

public void add(String name, String category, int amount) {
    Food.add(new Lists(name, category, amount));
}

public void emptyStock(int index) {
    Food.remove(index);
}

public void print() {
    for (Lists lists : Food) {
        System.out.println(lists);
    }
}

public static void main(String[] args) {
    Food food = new Food();
    food.add("Potato", "Vegetable", 35);
    food.add("Carrot", "Vegetable", 15);
    food.add("Apple", "Fruit", 30);
    food.add("Kiwi", "Fruit", 5);
    food.emptyStock(1);
    food.emptyStock(2);
    food.print();
    System.out.print("");
}
}

输出需要这样打印：

Potato is Vegetable and we have 35 kg in warehouse
Apple is Fruit and we have 30 kg in warehouse
20 kg of food has been sold! // my code cannot print this part

我仍然不确定如何使print()方法打印出已从列表中删除的食物总量（千克）。

Answer 1

只需添加一个 class 成员（在 class Food 中）来存储移除的总金额。在方法 emptyStock() 中，您更新了该成员的值。在下面的代码中，我添加了成员 removed.

import java.util.ArrayList;

public class Food {
    int removed;
    ArrayList<Lists> foods = new ArrayList<>();

    public void add(String name, String category, int amount) {
        foods.add(new Lists(name, category, amount));
    }

    public void emptyStock(int index) {
        removed += foods.get(index).getAmount();
        foods.remove(index);
    }

    public void print() {
        for (Lists lists : foods) {
            System.out.println(lists);
        }
        System.out.printf("%d kg of food has been sold!%n", removed);
    }

    public static void main(String[] args) {
        Food food = new Food();
        food.add("Potato", "Vegetable", 35);
        food.add("Carrot", "Vegetable", 15);
        food.add("Apple", "Fruit", 30);
        food.add("Kiwi", "Fruit", 5);
        food.emptyStock(1);
        food.emptyStock(2);
        food.print();
        System.out.print("");
    }
}

class Lists {
    private String name;
    private String category;
    private int amount;

    public Lists(String name, String category, int amount) {
       this.name = name;
       this.category = category;
       this.amount = amount;
    }

    public int getAmount() {
        return amount;
    }

    public String toString() {
        return name + " is " + category + " and we have " + amount + " in warehouse";
    }
}

当运行以上代码为：

时的输出

Potato is Vegetable and we have 35 in warehouse
Apple is Fruit and we have 30 in warehouse
20 kg of food has been sold!

如何从 ArrayList 中删除索引并打印已删除索引的总整数？

How to remove index from ArrayList and print total integer of the removed index?

java

methods

arraylist

tostring