我可以摆脱这个开关和枚举吗？

Question

我觉得这段代码可以通过某种方式利用多态性变得更清晰，但我似乎找不到合适的方法来做这件事。我尝试使用访问者模式，但没有成功。

有开关的"Hero"class：

public class Hero {
    private Equipment equipment = new Equipment();
    // other fields

    public void equipArmor(Armor armor) {
        findCorrespondingArmorSlot(armor).equipItem(armor);
    }

    private ItemSlot findCorrespondingArmorSlot(Armor armor) {
        switch (armor.getArmorType()) {
        case SHIELD:
            return equipment.offHand;
        case BODY:
            return equipment.body;
        case HEAD:
            return equipment.head;
        case GLOVES:
            return equipment.hands;
        case BOOTS:
            return equipment.feet;
        case BELT:
            return equipment.waist;
        case AMULET:
            return equipment.neck;
        case RING:
            return equipment.finger;
        case TRINKET:
            return equipment.special;
        }
        throw new NullPointerException();
    }

    public Equipment getEquipment() {
        return equipment;
    }

    // other methods

    public class Equipment {
        public ItemSlot mainHand = new ItemSlot();
        public ItemSlot offHand = new ItemSlot();
        public ItemSlot body = new ItemSlot();
        public ItemSlot head = new ItemSlot();
        public ItemSlot hands = new ItemSlot();
        public ItemSlot feet = new ItemSlot();
        public ItemSlot waist = new ItemSlot();
        public ItemSlot neck = new ItemSlot();
        public ItemSlot finger = new ItemSlot();
        public ItemSlot special = new ItemSlot();
    }

}

还有一些其他的东西：

public class ItemSlot {
    private static final Miscellaneous EMPTY = new Miscellaneous();

    private Item item = EMPTY;

    public Item getItem() {
        return item;
    }

    public void equipItem(Item item) {
        unequipItem();
        this.item = item;
    }

    public void unequipItem() {
        if (!isEmpty()) {
            item.addToInventory();
            item = EMPTY;
        }
    }

    public boolean isEmpty() {
        return (item == EMPTY);
    }
}

public abstract class Item {
    // fields

    public void addToInventory() {
        // code
    }

    // other methods
}

public class Miscellaneous extends Item{}

public class Armor extends Item {
    private ArmorType type;

    public ArmorType getArmorType() {
    return type;
    }

    //other methods
}

public enum ArmorType
{
    SHIELD, BODY, HEAD, GLOVES, BOOTS, AMULET, RING, BELT, TRINKET;
}

Answer 1

设备中的HashMap如何Class？

像这样：

public HashMap<String, ItemSlot> itemSlots = new ItemSlots HashMap<String, ItemSlot>();

然后在你的构造函数中：

itemSlots.put("mainHand ", new ItemSlot());

然后您必须像这样定义一个方法：

public ItemSlot getItemSlot(String item) {
  return itemSlots.get(item);
}

最后，您的案例将类似于：

return equipment.getItemSlot(armor.getArmorType());

Answer 2

是的，你可以摆脱开关。请记住，枚举只是静态保证的单例。所以他们可以有方法。只需按以下方式操作即可：

public enum ArmorType {
    SHIELD {
        public ItemSlot getItemSlot(Equipment e) { return e.offHand; }
    },
    // ... repeat for all other armor types
    TRINKET {
        public ItemSlot getItemSlot(Equipment e) { return e.special; }
    };

    public abstract ItemSlot getItemSlot(Equipment e);
}

然后你可以简单地调用armorType.getItemSlot(equiment);。

Answer 3

尝试以下操作：

public enum ArmorType
{
    SHIELD(){
        public ItemSlot getArmorSlot(Equipment equipment){
            return equipment.offHand;
        } 
    },
    ...

    public abstract ItemSlot getArmorSlot(Equipment equipment);
}

然后调用：

ItemSlot armorSlot = armor.getArmorType().getArmorSlot(equipment);

我可以摆脱这个开关和枚举吗？

Can I get rid of this switch and enum?

java

enums

switch-statement