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I'm experimenting with spigot plugins for my Minecraft server. In the process of attempting to create custom commands, such as heal & feed, I get the following error in my ide console for the main java file (MyFirstPlugin.java):

Method invocation 'setExecutor' may produce 'NullPointerException':14
Method invocation 'setExecutor' may produce 'NullPointerException':15

The full MyFirstPlugin.java file:

package me.nathan.myfirstplugin;

import me.nathan.myfirstplugin.commands.PluginCommands;
import me.nathan.myfirstplugin.events.PluginEvents;
import org.bukkit.ChatColor;
import org.bukkit.plugin.java.JavaPlugin;

public final class MyFirstPlugin extends JavaPlugin {

    @Override
    public void onEnable() {
        PluginCommands commands = new PluginCommands();
        getServer().getPluginManager().registerEvents(new PluginEvents(), this);
        getCommand("heal").setExecutor(commands);
        getCommand("feed").setExecutor(commands);
        getServer().getConsoleSender().sendMessage(ChatColor.AQUA + "[MyFirstPlugin]: Plugin is enabled!");
    }

    @Override
    public void onDisable() {
        // Plugin shutdown logic
        getServer().getConsoleSender().sendMessage(ChatColor.RED + "[MyFirstPlugin]: Plugin is disabled!");
    }
}

And this error for the commands class (PluginCommands.java):

Method invocation 'getDefaultValue' may produce 'NullPointerException':21

The full PluginCommands.java file:

package me.nathan.myfirstplugin.commands;

import org.bukkit.ChatColor;
import org.bukkit.attribute.Attribute;
import org.bukkit.command.Command;
import org.bukkit.command.CommandExecutor;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.Player;

public class PluginCommands implements CommandExecutor {
    @Override
    public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
        if (!(sender instanceof Player)) {
            sender.sendMessage("Only players can use that command!");
            return true;
        }
        Player player = (Player) sender;


        if (cmd.getName().equalsIgnoreCase("heal")){
            double maxHealth = player.getAttribute(Attribute.GENERIC_MAX_HEALTH).getDefaultValue();
            player.setHealth(maxHealth);
            sender.sendMessage(ChatColor.GREEN + "You have been healed!");
        }

        if (cmd.getName().equalsIgnoreCase("feed")){
            player.setFoodLevel(20);
            sender.sendMessage(ChatColor.GREEN + "You have been fed!");
        }

        return true;
    }
}

When I start the server and load the plugin, I get the following errors in the command prompt:

[23:13:20] [Server thread/ERROR]: Error occurred while enabling MyFirstPlugin v1.0-SNAPSHOT (Is it up to date?)
java.lang.NullPointerException: Cannot invoke "org.bukkit.command.PluginCommand.setExecutor(org.bukkit.command.CommandExecutor)" because the return value of "me.nathan.myfirstplugin.MyFirstPlugin.getCommand(String)" is null
        at me.nathan.myfirstplugin.MyFirstPlugin.onEnable(MyFirstPlugin.java:14) ~[?:?]
        at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:263) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:342) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:480) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at org.bukkit.craftbukkit.v1_17_R1.CraftServer.enablePlugin(CraftServer.java:505) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at org.bukkit.craftbukkit.v1_17_R1.CraftServer.enablePlugins(CraftServer.java:419) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at net.minecraft.server.MinecraftServer.loadWorld(MinecraftServer.java:604) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at net.minecraft.server.dedicated.DedicatedServer.init(DedicatedServer.java:266) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at net.minecraft.server.MinecraftServer.x(MinecraftServer.java:995) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at net.minecraft.server.MinecraftServer.lambda$0(MinecraftServer.java:303) ~[spigot-1.17.1.jar:3205-Spigot-18c71bf-6788550]
        at java.lang.Thread.run(Thread.java:831) [?:?]
[23:13:20] [Server thread/INFO]: Server permissions file permissions.yml is empty, ignoring it
[23:13:20] [Server thread/INFO]: Done (24.130s)! For help, type "help"

I feel like I have tried everything to fix this with my limited knowledge on the subject but if anyone could help, it would be very much appreciated :)

NATHAN TOLLEY
  • 133
  • 7
  • Well, taking a quick look at the [documentation](https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/plugin/java/JavaPlugin.html#getCommand(java.lang.String)), I see that `getCommand()` returns "the plugin command if found, otherwise null." Given that you haven't overriden this method in your `MyFirstPlugin` class, it seems logical that the default implementation would return null. It looks like you'll need to override the method and return an instance of `PluginCommand`. Otherwise, your `setExecutor()` call is the equivalent of `null.setExecutor(commands);`, hence the NullPointerException. – Charlie Armstrong Jul 29 '21 at 03:54
  • @CharlieArmstrong As I am proud to admit that I am very new to this as I have started this morning. Would you care to furthermore explain how to do that? – NATHAN TOLLEY Jul 29 '21 at 04:03

0 Answers0