当我加载我的我的世界时，我收到错误 java.lang.NullPointerExeption 我该如何解决这个问题？

Question

Hello so i am making a minecraft plugin here is the code

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

import me.EpicGamese.CustomEssentials.Main;
import me.EpicGamese.CustomEssentials.utils.Utils;

public class FlyCommand implements CommandExecutor {

    private Main plugin;

    public FlyCommand(Main plguin) {
        this.plugin = plugin;

        plugin.getCommand("fly").setExecutor(this);
    }

    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {

        if (!(sender instanceof Player)) {
            sender.sendMessage(Utils.chat(plugin.getConfig().getString("Hello")));
            return true;
        }

        Player p = (Player) sender;

        if (p.hasPermission("SubgGame.fly")) {
            if (p.isFlying()) {
                p.setAllowFlight(false);
                p.setFlying(false);
                p.sendMessage(Utils.chat(plugin.getConfig().getString("Hello")));
                return true;
            } else {
                p.setAllowFlight(true);
                p.setFlying(true);
                p.sendMessage(Utils.chat(plugin.getConfig().getString("Hello")));
            }
        } else {
            p.sendMessage(Utils.chat("Hello"));
        }

        return false;
    }

}

and when i try and load it into my server i get the error java.lang.NullPointerExeption can some one help and i am coding the plugin for 1.8.8 minecraft

Answer 1

Line 18 is your NPE. Here's the problem:

private Main plugin;

public FlyCommand(Main plguin) {
    this.plugin = plugin;

    plugin.getCommand("fly").setExecutor(this);
}

You defined a Main plugin which will default to NULL. In FlyCommand you get passed a variable you called plguin and then you assign this.plugin to plugin (assigning it to itself, not the value passed into the func b/c you misspelled that).

You probably meant to:

this.plugin = plguin;

Notice the gui vs ugi. To void this and make the code more readable I would call that argument passed into the function something more different, maybe just p .

private Main plugin;

public FlyCommand(Main p) {
    this.plugin = p;

    plugin.getCommand("fly").setExecutor(this);
}