Is this better than doing a Singleton class?

Main (open) Main (close)

Code:

package com.WDI.main;

import org.bukkit.Bukkit;
import org.bukkit.plugin.java.JavaPlugin;

import com.WDI.listeners.JoinEvent;
import com.WDI.managers.ConfigManager;
import com.WDI.managers.PacketManager;
import com.WDI.managers.RoleManager;
import com.WDI.utils.MessageUtil;

public class WDI extends JavaPlugin {

    private ConfigManager configManager;
    private PacketManager packetManager;
    private MessageUtil messageUtil;
    private RoleManager roleManager;

    public void onEnable() {

        configManager = new ConfigManager(this);
        packetManager = new PacketManager(this);
        messageUtil = new MessageUtil(this);
        roleManager = new RoleManager(this);
       
        getConfigManager().setDefaults();

        registerEvents();
    }

    private void registerEvents() {
        Bukkit.getPluginManager().registerEvents(new JoinEvent(this), this);
    }

    public ConfigManager getConfigManager() {
        return configManager;
    }

    public PacketManager getPacketManager() {
        return packetManager;
    }

    public MessageUtil getMessageUtil() {
        return messageUtil;
    }

}

WDIListener Class (open) WDIListener Class (close)

Code:

package com.WDI.main;

import org.bukkit.event.Listener;

public class WDIListener implements Listener {

    protected WDI plugin;

    public WDIListener(WDI pl) {
        plugin = pl;
    }

}

Join Event (open) Join Event (close)

Code:

package com.WDI.listeners;

import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.player.AsyncPlayerPreLoginEvent;
import org.bukkit.event.player.AsyncPlayerPreLoginEvent.Result;
import org.bukkit.event.player.PlayerJoinEvent;

import com.WDI.game.GameState;
import com.WDI.main.WDI;
import com.WDI.main.WDIListener;

public class JoinEvent extends WDIListener {

    public JoinEvent(WDI pl) {
        super(pl);
    }

    @EventHandler
    public void onJoin(PlayerJoinEvent e) {

        Player p = e.getPlayer();

        switch (GameState.getState()) {

        case LOBBY:
            e.setJoinMessage(plugin.getMessageUtil().msg("&2&l+&7" + p.getName(), false));
            break;

        case GAME:
            e.setJoinMessage(plugin.getMessageUtil().msg("&2&l+&7" + p.getName(), false));
            plugin.getMessageUtil().msg(p, "&4You have been set as a spectator - &4&lGAME STARTED", false);
            // Set person to spectator mode
            break;

        default:
            break;

        }

    }

    @EventHandler
    public void onPreLogin(AsyncPlayerPreLoginEvent e) {

        if (GameState.isState(GameState.RESTARTING))
            e.disallow(Result.KICK_OTHER,
                    plugin.getMessageUtil().msg("&4&lServer restarting... try again in a moment", true));

    }

}

If I need to use the main class inside of different object classes would this be better than doing a singleton class for each object? Inside of MessageUtil and ConfigManager those classes extend WDIListener so I can call plugin.whatever

In my last attempt at this plugin, I remember getting the occasional NPE because of WDI not being accessible, just want to double check this will work in its pre-stages before making the whole plugin.

 

@timtower Alright, thank you!