我可以使用原始类作为类型并仍然使用它的子类吗？

Question

我正在编写此代码，并且碰巧将类型作为原始类。现在，如果我将变量与其子类（扩展类）一起插入，则会出错。我正在运行一个 Spigot 插件，但显然这个问题与 Spigot 本身无关，而是我对 Java 缺乏了解。

我无法提出任何单一的解决方案，我已经查看了所有内容。

编辑（我的解释）：如果您查看 PlayerClass，您会看到一个名为 Kit 的变量，它使用 KitClass 类型。如果您查看 KitClass，它是一个包含一个名为 Alchemist 的子类的类。我的问题是，KitClass 类型是否包含所有继承类和原始类？如果不是，那么我必须对 PlayerClass 中的 Kit 变量使用什么类型/修改才能允许将 Alchemist 类的实例设置为 Kit 变量？

package me.kckeith.KitPvP;

import org.bukkit.entity.Player;

public class PlayerClass {
    public Player Player;
    public double Coins;
    public KitClass Kit;

    public PlayerClass(Player Player, double Coins, KitClass Kit) {
        this.Player = Player;
        this.Coins = Coins;
        this.Kit = Kit;
    }

    public void setKit(KitClass Kit) {
        this.Kit = Kit;
        this.Kit.giveStuff();
    }
}

package me.kckeith.KitPvP;

import org.bukkit.Bukkit;
import org.bukkit.Material;
import org.bukkit.entity.Player;

import net.md_5.bungee.api.ChatColor;

public class KitClass {
    public Player Player;
    public Material InventoryIcon;

    public KitClass(Player player) {
        this.Player = player;
    }

    public void giveStuff() {
        Bukkit.getServer().getConsoleSender().sendMessage(ChatColor.GOLD + "Given items!");
    }
}

package me.kckeith.KitPvP.Kits;

import org.bukkit.Material;
import org.bukkit.enchantments.Enchantment;
import org.bukkit.entity.Player;
import org.bukkit.inventory.ItemStack;
import org.bukkit.inventory.meta.PotionMeta;
import org.bukkit.potion.PotionEffect;
import org.bukkit.potion.PotionEffectType;

import me.kckeith.KitPvP.KitClass;

public class Alchemist extends KitClass {
    public static Material InventoryIcon = Material.SPLASH_POTION;

    public Alchemist(Player player) {
        super(player);
    }

    public void giveStuff() {
        // Clear items

        this.Player.getInventory().clear();

        // Give the player their armor

        ItemStack[] Armor = new ItemStack[4];
        Armor[0] = new ItemStack(Material.LEATHER_BOOTS);
        Armor[1] = new ItemStack(Material.LEATHER_LEGGINGS);
        Armor[2] = new ItemStack(Material.LEATHER_CHESTPLATE);
        Armor[3] = new ItemStack(Material.LEATHER_HELMET);

        // Add Enchants
        Armor[0].addEnchantment(Enchantment.PROTECTION_ENVIRONMENTAL, 1);
        Armor[1].addEnchantment(Enchantment.PROTECTION_ENVIRONMENTAL, 1);
        Armor[2].addEnchantment(Enchantment.PROTECTION_ENVIRONMENTAL, 1);
        Armor[3].addEnchantment(Enchantment.PROTECTION_ENVIRONMENTAL, 1);

        // Give Armor
        this.Player.getInventory().setArmorContents(Armor);

        // Give Golden Sword

        ItemStack GoldenSword = new ItemStack(Material.GOLDEN_SWORD);
        GoldenSword.addEnchantment(Enchantment.DURABILITY, 1);

        this.Player.getInventory().addItem(GoldenSword);

        // Give Regen Potions

        ItemStack RegenPotion = new ItemStack(Material.POTION, 4);
        PotionMeta RegenPotionMeta = (PotionMeta) RegenPotion.getItemMeta();
        RegenPotionMeta.addCustomEffect(new PotionEffect(PotionEffectType.REGENERATION, 20, 2), true);
        RegenPotion.setItemMeta(RegenPotionMeta);

        this.Player.getInventory().addItem(RegenPotion);

        // Give Damage Potions
        ItemStack DamagePotion = new ItemStack(Material.SPLASH_POTION, 8);
        PotionMeta DamagePotionMeta = (PotionMeta) DamagePotion.getItemMeta();
        DamagePotionMeta.addCustomEffect(new PotionEffect(PotionEffectType.HARM, 0, 2), true);
        DamagePotion.setItemMeta(DamagePotionMeta);

        this.Player.getInventory().addItem(DamagePotion);

        super.giveStuff();
    }
}

我认为具体的错误是 NullStackException 但我不确定。我在代码顶部更详细地讨论了这个问题。

Answer 1

我的问题是 KitClass 类型是否包含所有继承的类和原始类？

是的，所以当您创建 Alchemist 时，您仍然可以使用所有 KitClass 方法。这是正确的：Alchemist myAlchemistObject = new Alchemist(myPlayer);

---

您有很多可能令人困惑的代码。您不应该有同名的类和对象/变量。

例如，当声明一个变量时这是不好的：

public Player Player;

但这是清晰易读的：

public Player player;

这又好了，不会有混淆/混乱：

public Player myPlayer;

另一个例子。这还不清楚：

            PlayerClass PlayerClass = MainClass.PlayerList.get(Player.getUniqueId());
            Alchemist Alchemist = new Alchemist(Player);
            PlayerClass.Kit = Alchemist;
            PlayerClass.Kit.giveStuff();

这很容易理解：

            PlayerClass myPlayerObject = MainClass.PlayerList.get(myPlayer.getUniqueId());
            Alchemist myAlchemistObject = new Alchemist(myPlayer);
            myPlayerObject.Kit = myAlchemistObject;
            myPlayerObject.Kit.giveStuff();