java - Minecraft NPC 没有在服务器上生成并攻击我 : null pointer error

Question

这个问题已经有答案了:

What is a NullPointerException, and how do I fix it? (12 个回答)

已关闭 6 年前。

当我加入我的服务器时，“测试”会按预期打印，但 npc 不会生成，也不会攻击我。这是plugin.yml:

main: com.megacrafting.MegaParty
version: 1.0
name: Megaparty
depend: [Citizens]

这是错误:

[20:58:24 ERROR]: Could not pass event PlayerJoinEvent to Megaparty v1.0
org.bukkit.event.EventException: null
        at     org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306)  ~[spigot.jar:git-Spigot-b78586d-f3356f1]
        at     org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-b78586d-f3356f1]
    at   org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:499) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:484) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.PlayerList.onPlayerJoin(PlayerList.java:342) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.PlayerList.a(PlayerList.java:162) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.LoginListener.b(LoginListener.java:159) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.LoginListener.e(LoginListener.java:57) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.NetworkManager.a(NetworkManager.java:233) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.ServerConnection.c(ServerConnection.java:140) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:842) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:405) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:678) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:576) [spigot.jar:git-Spigot-b78586d-f3356f1]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_131]
Caused by: java.lang.NullPointerException
    at com.megacrafting.MegaParty.onJoin(MegaParty.java:35) ~[?:?]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_131]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_131]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_131]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_131]
    at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot.jar:git-Spigot-b78586d-f3356f1]
    ... 14 more

这是代码:

package com.megacrafting;
import org.bukkit.Bukkit;
import org.bukkit.Location;
import org.bukkit.entity.EntityType;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.plugin.java.JavaPlugin;

import net.citizensnpcs.api.CitizensAPI;
import net.citizensnpcs.api.npc.NPC;
import net.citizensnpcs.api.npc.NPCRegistry;



public class MegaParty extends JavaPlugin implements Listener {

private NPCRegistry registry;



public void onEnable() {
    NPCRegistry registry = CitizensAPI.getNPCRegistry();
    getServer().getPluginManager().registerEvents(this, this);


}

@EventHandler
   public void onJoin(PlayerJoinEvent event) {
    Player p = event.getPlayer();
    p.sendMessage("testing");
    Location loc = p.getLocation();
    NPC npc = registry.createNPC(EntityType.PLAYER, "keys9");
    npc.spawn(loc);

    npc.getNavigator().setTarget(p, true);

    }

}

Answer 1

您的字段 registry 为 NULL，因为您从未在 onEnable 中设置它。

将 onEnable 更改为

public void onEnable() {
    this.registry = CitizensAPI.getNPCRegistry();
    getServer().getPluginManager().registerEvents(this, this); 
}