Unable to put instance of object into HashMap

Hello. I've been testing my code below, however it doesn't work. The problem indicates that plugin

Code:

 Couldn't pass event PlayerJoinEvent() to Main.java 

Problem vanishes when I delete

Code:

 playerStats.put(player.getUniqueId(), stats); 

Is there anything wrong with my Strength instance? I would be glad for any kind of help. I know I have many unnecessary imports and empty class extending Base class isn't necessary. Everything was for the sake of testing.


Main.java:

Code:

package osl.First;
import java.util.HashMap;
import java.util.UUID;
import org.bukkit.ChatColor;
import org.bukkit.entity.Player;
import org.bukkit.plugin.java.JavaPlugin;
import commands.NewCommand;
import events.TutorialEvents;
import stats.Statistics;
import stats.Strength;
public class Main extends JavaPlugin {
    private static HashMap<UUID, Strength> playerStats = new HashMap<UUID, Strength>();
   
    @Override
    public void onEnable() {
        NewCommand cmd = new NewCommand();
        getServer().getPluginManager().registerEvents(new TutorialEvents(), this);
        getServer().getConsoleSender().sendMessage(ChatColor.RED + "PLUGIN IS ENABLEEEEEEEEEEED.");
    }
   
    @Override
    public void onDisable() {
        System.out.println(ChatColor.GREEN + "Plugin disabled.");
    }
   
    public static HashMap<UUID, Strength> getMap() {
        return playerStats;
    }
}

Strength.java

Code:

package stats;
public class Strength extends Base {
   
}

Base.java:

Code:

package stats;
public class Base {
    protected int amount;
    public void setAmount(int newAmount) {
        amount = newAmount;
    }
    public int getAmount() {
        return amount;
    }
}

TutorialEvents.java

Code:

package events;
import java.util.HashMap;
import java.util.List;
import java.util.UUID;
import org.bukkit.ChatColor;
import org.bukkit.Material;
import org.bukkit.entity.Entity;
import org.bukkit.entity.Player;
import org.bukkit.entity.Zombie;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityDeathEvent;
import org.bukkit.event.player.PlayerJoinEvent;
import org.bukkit.event.player.PlayerMoveEvent;
import org.bukkit.inventory.ItemStack;
import osl.First.Main;
import stats.Statistics;
import stats.Strength;
public class TutorialEvents implements Listener {
    @EventHandler
    public static void onPlayerJoin(PlayerJoinEvent event) {
        Strength stats = new Strength();
        HashMap<UUID, Strength> playerStats = Main.getMap();
        Player player = event.getPlayer();
        if (!(playerStats.containsKey(event.getPlayer().getUniqueId()))) {
            playerStats.put(player.getUniqueId(), stats);
            player.sendMessage("You've been put.");
        }
        else
        {
            player.sendMessage("You're already in hashmap ");
        }
    }

 

i guess this is because the class is just empty?
u need to make base and Strength class a constructor like this:

public class Base{
public Base(int amount){
// i believe u know how to do this and i m posting this structure for fun... :|
}
}
also... i m not sure if this would work... so try it out and please post the whole whole error log...

 

Post the full stack trace.

 

The solution was simple, I should initialize amount variable. So you can do it as

Code:

protected int amount = 0;