Class不存在和存在

Question

我收到一个 NoClassDefFoundError 异常，我不知道为什么，因为我的 class 是导入的，编译器中没有错误，但是当我运行插件时，错误是。我什至检查了 .class 文件是否存在于 .jar 文件中并且它存在所以我不知道这里的问题是我得到的异常：

[22:45:24] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'sb' in plugin YTScoreboard v2.6.3
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:149) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at org.bukkit.craftbukkit.v1_16_R3.CraftServer.dispatchCommand(CraftServer.java:761) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.PlayerConnection.handleCommand(PlayerConnection.java:1936) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.PlayerConnection.c(PlayerConnection.java:1779) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.PlayerConnection.a(PlayerConnection.java:1732) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.PacketPlayInChat.a(PacketPlayInChat.java:49) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.PacketPlayInChat.a(PacketPlayInChat.java:1) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.PlayerConnectionUtils.lambda[=11=](PlayerConnectionUtils.java:28) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.TickTask.run(SourceFile:18) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeTask(SourceFile:144) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeNext(SourceFile:118) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.MinecraftServer.bb(MinecraftServer.java:1061) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.MinecraftServer.executeNext(MinecraftServer.java:1054) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.IAsyncTaskHandler.executeAll(SourceFile:103) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.MinecraftServer.sleepForTick(MinecraftServer.java:1037) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:970) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at net.minecraft.server.v1_16_R3.MinecraftServer.lambda[=11=](MinecraftServer.java:273) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        at java.lang.Thread.run(Thread.java:831) [?:?]
Caused by: java.lang.NoClassDefFoundError: Could not initialize class pl.Werokowy.ytscoreboard.ScoreboadAPI
        at pl.Werokowy.ytscoreboard.SBCmd.onCommand(SBCmd.java:57) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[1.16.jar:3096a-Spigot-9fb885e-af1a232]
        ... 19 more

代码非常简单，所以我不想展示它：ScoreboardAPI.updateScoreboard()

Answer 1

如果 classes 在编译期间没有产生问题并且 jar 文件是从中构建的，我假设两个 classes 是同一个 jar 的一部分，因此 class路径不是问题。

查看 NoClassDefFoundError 中的文本：无法初始化 class pl.Werokowy.ytscoreboard.ScoreboadAPI

这不是“ClassNotFoundException”，它指向构建 class 或实例时出现的问题。也许不是构造函数抛出异常，但也可能是除了构造函数之外甚至 class 级别需要运行的代码。

检查您的变量定义（以及它们的初始化方式），并检查静态初始化程序。

Class不存在和存在

Class does not exist and exists

java

eclipse

exception

plugins

spigot