java - craftbukkit.v1_15_R1.entity.CraftPlayer 无法转换

Question

我英语不好，但我必须询问这个错误，因为我无法在任何地方修复它。

我正在制作我的世界插件来返回到玩家选择的位置。

但我无法修复这个错误...

这是整个错误日志

[10:57:29] [Server thread/INFO]: Player issued server command: /setposition
[10:57:29] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'setposition' in plugin Main v0.1
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:47) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:149) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at org.bukkit.craftbukkit.v1_15_R1.CraftServer.dispatchCommand(CraftServer.java:723) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.PlayerConnection.handleCommand(PlayerConnection.java:1658) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.PlayerConnection.a(PlayerConnection.java:1498) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.PacketPlayInChat.a(PacketPlayInChat.java:47) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.PacketPlayInChat.a(PacketPlayInChat.java:1) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.PlayerConnectionUtils.lambda$0(PlayerConnectionUtils.java:19) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.TickTask.run(SourceFile:18) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeTask(SourceFile:144) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.executeNext(SourceFile:118) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.MinecraftServer.ba(MinecraftServer.java:918) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.MinecraftServer.executeNext(MinecraftServer.java:911) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.awaitTasks(SourceFile:127) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.MinecraftServer.sleepForTick(MinecraftServer.java:895) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:828) [Server.jar:git-Spigot-6de3d4b-fc24934]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_241]
Caused by: java.lang.ClassCastException: org.bukkit.craftbukkit.v1_15_R1.entity.CraftPlayer cannot be cast to package1.PlayerPosition
        at package1.SetPosition.onCommand(SetPosition.java:16) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:45) ~[Server.jar:git-Spigot-6de3d4b-fc24934]
        ... 17 more

返回命令

玩家可以通过setposition命令到达选定的位置

package package1;

import org.bukkit.command.Command;
import org.bukkit.command.CommandExecutor;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;
import net.md_5.bungee.api.ChatColor;

public class Back implements CommandExecutor {

    public boolean onCommand(CommandSender sender, Command command, String label, String[] args)
    {
        if(sender instanceof Player) {
            Player p = (Player) sender;
            PlayerPosition pp = (PlayerPosition) p;
            if(pp.location.equals(null)) {
                p.sendMessage(ChatColor.RED + "Set Your Position To Back First By Using SetPosition.");
                return false;

            }
            else 
            {

                p.teleport(pp.location);
            return true;

            }

        }
        return false;
    }

}

这是 PlayerPosition 类

此类扩展了 Player

和添加位置

package package1;

import org.bukkit.Location;
import org.bukkit.entity.Player;

public abstract class PlayerPosition implements Player {
    public Location location;

    PlayerPosition(Location l){
        this.location = l;
    }



}

这是 setposition 命令。

package package1;

import org.bukkit.command.Command;
import org.bukkit.command.CommandExecutor;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;

import net.md_5.bungee.api.ChatColor;

public class SetPosition implements CommandExecutor {

    public boolean onCommand(CommandSender sender, Command command, String label, String[] args)
    {
        if(sender instanceof Player) {
            Player p = (Player) sender;
            PlayerPosition pp = (PlayerPosition) p;

            pp.location = p.getLocation();

            p.sendMessage(ChatColor.BLUE + "Position Setting Complete.");
            return true;



        }   
    return false;

    }

}

如何修复它？

Answer 1

Player是一个接口(interface)，而不是一个类，因此任何实现Player接口(interface)的类也必须实现Player中的所有方法。

示例:

public interface MyInterface {
    public void aMethod();
}

如果您有一个实现 myIntefrace 的类，那么您的类必须实现 aMethod:

public class MyClass implements MyInterface {
    public void aMethod() {
        //Do something
    }
}

有关更多信息，请参阅此处:Java Interfaces

因此，如果您希望 PlayerPosition 实现 Player，您必须自己实现 Player 接口(interface)中包含的大量方法。因此根本不推荐。

正因为如此，您无法从 CraftPlayer 转换到 PlayerPosition。

解决方法是将玩家位置保存在 /setposition 上的 HashMap 中，并在 back 上从中获取它。

您的问题的解决方案可能如下:

SetPosition.java:

public class SetPosition implements CommandExecutor {
    @Override
    public boolean onCommand(CommandSender theSender, Command command, String s, String[] strings) {
        if (theSender instanceof Player) {
            Player p = (Player) theSender;
            PluginCore.getInstance().setLocation(p, p.getLocation());
            p.sendMessage(ChatColor.BLUE + "Position Setting Complete.");
        }
        return false;
    }
}

返回.java:

public class Back implements CommandExecutor {
    @Override
    public boolean onCommand(CommandSender theSender, Command command, String s, String[] strings) {
        if (theSender instanceof Player) {
            Player p = (Player) theSender;
            Location location = PluginCore.getInstance().getLocation(p);
            if (location == null) {
                p.sendMessage(ChatColor.RED + "Set Your Position To Back First By Using SetPosition.");
            } else {
                p.teleport(location);
            }
        }
        return false;
    }
}

PluginCore.java:(主类)

public class PluginCore extends JavaPlugin {

    private static PluginCore instance;

    private HashMap<Player, Location> locations = new HashMap<Player, Location>();

    @Override
    public void onEnable() {
        instance = this;
        this.getCommand("back").setExecutor(new Back());
        this.getCommand("setposition").setExecutor(new SetPosition());
    }

    public static PluginCore getInstance() {
        return instance;
    }

    public Location getLocations(Player p) {
        return locations.get(p);
    }

    public void setLocation(Player p, Location location) {
        this.locations.put(p, location);
    }
}

希望对您有帮助!