建议更好的解决方案，从列表中选择项目

Question

我想在控制台中用数字列出物品(每个物品都有一个满足饥饿的值)，因此用户可以通过输入物品的编号来选择物品。

1. 热狗3
2. 蛋糕2

我用所有食物和值的HashMap创建了一个类Food。在另一个类(OhterClass)中，我想列出项目和值并处理用户输入。我的目标是读出所选项的值并将其添加到数据字段:hunger.

当我这样做的时候，我必须在OtherClass中创建一个foreach，并通过索引读取每个项目和值，我还必须检查用户输入的开关情况，但我认为这个解决方案不是很好，但我不知道如何解决它。

有人给我一些建议吗?

Answer 1

你可以试试:

public class Hunger {
    public static void main(String[] args) {
        for (Food food : Food.values()) {
            System.out.printf("%d   %-8s %dn", food.ordinal(), food.caption, food.sustenance);
        }
        System.out.print("Hungry? Make your choice: ");
        Scanner scanner = new Scanner(System.in);
        Food food;
        while (true) {
            try {
                food = Food.values()[scanner.nextInt() - 1];
                break;
            } catch (Exception e) {
                System.out.println("Naa ... choose again: ");
            }
        }
        System.out.printf("This %s was yummy!n", food.caption);
    }
}
enum Food {
    HOT_DOG("Hot Dog", 3),
    CUP_CAKE("Cup Cake", 2);
    final String caption;
    final int sustenance;
    private Food(String caption, int sustenance) {
        this.caption = caption;
        this.sustenance = sustenance;
    }
}

Answer 2

尝试为您的解决方案实现一个访问者模式。

它看起来像:

public interface FoodVisitor {
    void visit(FoodType food);
}
public interface FoodType {
    void accept(FoodVisitor visitor);
    String getName();
}
public class HotDog implements FoodType {
    public void accept(FoodVisitor visitor) {
        visitor.visit(this);
    }
    public String getName() {
        return "Hot Dog";
    }
}
public class FoodVisitorImpl implements FoodVisitor {
    public void visit(FoodType food) {
        System.out.println("Enter the amount of " + food.getName() + " you would like");
        Scanner in= ....
        //Get the amount, save it in a field in the visitor
    }
}
public class Demo {
    public static void main(String ... args) {
        FoodVisitorImpl visitor= new FoodVisitorImpl();
        for (FoodType food : foodList) {
            food.accept(visitor);
        }
        //also, implement a certain getResult() method in the visitor
        System.out.println(visitor.getResult());
    }
}