此ItemBuilder有什么问题？

Question

我为Minecraft 1.8.9创建了自己的ItemBuilder类。如果现在尝试使用addLore("Test")，则行lore.add(s);会出现空指针异常。我不知道问题是什么或如何解决。

public class ItemBuilder{
    Material material;
    int amount = 1;
    short damage = 0;
    Byte subid = 0;
    List<String> lore;
    String name = "";

    //builder
    public ItemBuilder(Material material){
        this.material = material;
    }

    public ItemBuilder(Material material, Byte subid){
        this.material = material;
        this.subid = subid;
    }

    public ItemBuilder setDamage(int damage){
        this.damage = (short) damage;
        return this;
    }

    public ItemBuilder setLore(List<String> lore){
        this.lore = lore;
        return this;
    }

    public ItemBuilder addLore(String s){
        List<String> lore = this.lore;
        lore.add(s);
        this.lore = lore;
        return this;
    }

    public ItemBuilder setDisplayName(String s){
        this.name = s;
        return this;
    }

    public ItemStack build(){
        ItemStack itemStack = new ItemStack(this.material, this.amount, this.damage, this.subid);
        ItemMeta itemMeta = itemStack.getItemMeta();
        itemMeta.setDisplayName(this.name);
        itemMeta.setLore(this.lore);
        itemStack.setItemMeta(itemMeta);
        return itemStack;
    }
}

Answer 1

哦，是的，已经解决了。

我只需要更改清单知识；至列表知识=新的LinkedList <>（）;