Solved NullPointerException when trying to removePlayer from BossBar?

I'm trying to make a bossbar that counts down the cooldown of abilities in a game mode i'm trying to make. The code works, and the bossbar appears for the player, but I get a NullPointerException when trying to remove the bossbar from the player.

notifications.getCooldownBar().removeAll();
is the line of code that gives me the exception.

Code (Text):

package lucien.HardcoreGames.game;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;

import org.bukkit.Bukkit;
import org.bukkit.NamespacedKey;
import org.bukkit.boss.BarColor;
import org.bukkit.boss.BarStyle;
import org.bukkit.boss.BossBar;
import org.bukkit.entity.Player;
import org.bukkit.scheduler.BukkitRunnable;

public class Cooldowns {
    public static ConcurrentHashMap<UUID, Integer> cooldowns = new ConcurrentHashMap<UUID, Integer>();
    public static List<Player> hasBarShown = new ArrayList<Player>();

    public static void startCooldownTimer() {
    new BukkitRunnable() {
        @Override
        public void run() {
        //If there are players with cooldowns
        if(!cooldowns.isEmpty()) {
            //For every player with a cooldown
            for(UUID uuid : cooldowns.keySet()) {
            //Save their remaining cooldown time
            int timeleft = cooldowns.get(uuid);
            //Save the player
            Player player = Bukkit.getPlayer(uuid);
            NotificationManager notifications = new NotificationManager();
            NamespacedKey barNameKey = new NamespacedKey(Main.plugin, "cooldownBar");
            //If the player has a cooldown
            if(timeleft > 0) {
                //Remove 1 second from their cooldown
                cooldowns.put(uuid, timeleft - 1);
                Bukkit.broadcastMessage("" + timeleft);
                if(!hasBarShown.contains(player)) {
                hasBarShown.add(player);
                notifications.createCooldownBar(barNameKey, "test", BarColor.YELLOW, BarStyle.SOLID);
                BossBar cooldownBar = notifications.getCooldownBar();
                cooldownBar.addPlayer(player);
                }
            }
            //If the player dosen't have a cooldown
            else {
                //Remove them from the list of players with a cooldown
                cooldowns.remove(uuid);
                Bukkit.getServer().removeBossBar(barNameKey);
                notifications.getCooldownBar().removeAll();
                hasBarShown.remove(player);
            }
            }
        }
        }
    }.runTaskTimer(Main.plugin, 0, 20);
    }
}
 

Here is the NotificationManager class I used for action bar messages and boss bars.

Code (Text):

package lucien.HardcoreGames.game;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.NamespacedKey;
import org.bukkit.boss.BarColor;
import org.bukkit.boss.BarFlag;
import org.bukkit.boss.BarStyle;
import org.bukkit.boss.BossBar;
import org.bukkit.entity.Player;

import com.connorlinfoot.actionbarapi.ActionBarAPI;

public class NotificationManager {
    public static NamespacedKey gracePeriodBarNameKey = new NamespacedKey(Main.plugin, "gracePeriod");
    public static BossBar gracePeriodBar = Bukkit.getServer().createBossBar(gracePeriodBarNameKey, ChatColor.translateAlternateColorCodes('&', "&5&lGrace Period: &f10 minutes"), BarColor.WHITE, BarStyle.SEGMENTED_10, new BarFlag[0]);
    private BossBar cooldownBar;
 
    public static void showBossBar(BossBar barToShow, Player playerToShow) {
    barToShow.setVisible(true);
    barToShow.addPlayer(playerToShow);
    }
 
    public void createCooldownBar(NamespacedKey nameKey, String title, BarColor color, BarStyle style) {
    cooldownBar = Bukkit.getServer().createBossBar(nameKey, title, color, style, new BarFlag[0]);
    }
 
    public BossBar getCooldownBar() {
    return cooldownBar;
    }
}
 

Any help is appreciated, thanks in advance.

EDIT: To clarify, the boss bar remains on the player's screen, and is not removed by
Bukkit.getServer().removeBossBar(barNameKey);
and
notifications.getCooldownBar().removeAll();
gives me a NullPointerException.

 

Would I put the
NotificationManager notifications = new NotificationManager();
line as the first line of the startCooldownTimer() method? Or make a separate method that creates NotificationManagers? I'm new so i apologize if these questions are dumb.

 

I think got it! Here's the finished code:

Code (Text):

package lucien.HardcoreGames.game;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.boss.BossBar;
import org.bukkit.entity.Player;
import org.bukkit.scheduler.BukkitRunnable;

public class Cooldowns {
    public static ConcurrentHashMap<UUID, NotificationManager> cooldowns = new ConcurrentHashMap<UUID, NotificationManager>();
    public static HashMap<String, Integer> cooldownMasterList = new HashMap<String, Integer>();
    public static List<Player> hasBarShown = new ArrayList<Player>();

    public static void startCooldownTimer() {
    new BukkitRunnable() {
        @Override
        public void run() {
        if(!cooldowns.isEmpty()) {
            for(UUID uuid : cooldowns.keySet()) {
            Player player = Bukkit.getPlayer(uuid);
            NotificationManager notifications = cooldowns.get(uuid);
            int timeleft = notifications.getRemainingCooldown();
            BossBar cooldownBar = notifications.getCooldownBar();

            if(timeleft > 0) {
                notifications.setRemainingCooldown(timeleft - 1);
                int masterCooldown = cooldownMasterList.get(ChosenKits.playerKits.get(player.getName()));
                if(masterCooldown != timeleft) {
                if(cooldownBar.getProgress() - (1.0/masterCooldown) >= 0.0)
                    cooldownBar.setProgress(cooldownBar.getProgress() - (1.0/masterCooldown));
                else
                    cooldownBar.setProgress(0.0);
                cooldownBar.setTitle(ChatColor.translateAlternateColorCodes('&', "&8&lCooldown: &e" + timeleft));
                }
            }
            else {
                cooldowns.remove(uuid);
                notifications.getCooldownBar().removePlayer(player);
            }
            }
        }
        }
    }.runTaskTimer(Main.plugin, 0, 20);
    }

    public static void fillMasterList() {
    cooldownMasterList.put("Thor", 10);
    }
}
 

and the NotificationManager:

Code (Text):

package lucien.HardcoreGames.game;

import org.bukkit.Bukkit;
import org.bukkit.ChatColor;
import org.bukkit.NamespacedKey;
import org.bukkit.boss.BarColor;
import org.bukkit.boss.BarFlag;
import org.bukkit.boss.BarStyle;
import org.bukkit.boss.BossBar;
import org.bukkit.entity.Player;

import com.connorlinfoot.actionbarapi.ActionBarAPI;

public class NotificationManager {
    public static NamespacedKey gracePeriodBarNameKey = new NamespacedKey(Main.plugin, "gracePeriod");
    public static BossBar gracePeriodBar = Bukkit.getServer().createBossBar(gracePeriodBarNameKey, ChatColor.translateAlternateColorCodes('&', "&5&lGrace Period: &f10 minutes"), BarColor.WHITE, BarStyle.SEGMENTED_10, new BarFlag[0]);
    private BossBar cooldownBar;
    private int cooldown;
   
    public NotificationManager(NamespacedKey nameKey, String title, BarColor color, BarStyle style, double progress, Player player, int cooldown) {
    cooldownBar = Bukkit.getServer().createBossBar(nameKey, title, color, style, new BarFlag[0]);
    cooldownBar.setProgress(1.0);
    cooldownBar.addPlayer(player);
    this.cooldown = cooldown;
    }
   
    public static void showBossBar(BossBar barToShow, Player playerToShow) {
    barToShow.setVisible(true);
    barToShow.addPlayer(playerToShow);
    }

    public static void playerInfoActionBar(Player attacker, Player victim) {
    if(!Tracking.cooldowns.containsKey(attacker.getUniqueId())) {
        String kitToDisplay = ChatColor.WHITE + "None";
        if(ChosenKits.playerKits.get(victim.getName()) != null)
        kitToDisplay = ChatColor.WHITE + ChosenKits.playerKits.get(victim.getName());
        ActionBarAPI.sendActionBar(attacker, ChatColor.translateAlternateColorCodes('&', "&5&lTarget: &f" + victim.getName() + " &5&lKit: &f" + kitToDisplay), 60);
    }
    }

    public BossBar getCooldownBar() {
    return cooldownBar;
    }
   
    public int getRemainingCooldown() {
    return cooldown;
    }
   
    public void setRemainingCooldown(int cooldown) {
    this.cooldown = cooldown;
    }
}
 

This makes it so that each player can have their own cooldown boss bar. Thank you so much for your suggestion, if there is anything else I could do to make this run better (less laggy) please let me know