Solved help, my config is unable to update and i dont know what did i do wrong

I am a noob who started to learn Bukkit.Plugin 3 days ago...

Code:

package me.yuanjv.worldsender;

import org.bukkit.configuration.file.FileConfiguration;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.player.PlayerChangedWorldEvent;

import java.util.*;

public class Recorder implements Listener {
    @EventHandler
    public void changeWorld(PlayerChangedWorldEvent e) {
        FileConfiguration configuration= WorldSender.plugin.getConfig();
        String p = e.getPlayer().getName();
        String w = e.getFrom().getName();
        String[] arr = w.split("_", 0);
        String mainW=arr[0];
        List<String> l;
        String old = null;
        if (configuration.contains(p)){
            l = configuration.getStringList(p);
            for (String name : l) {
                if (name.equals(mainW) || name.equals(mainW + "_nether") || name.equals(mainW + "_the_end")) {
                    old = name;
                }
            }

            configuration.getStringList(p).remove(old);
            configuration.getStringList(p).add(w);
        }else{
            List<String> newW= new ArrayList<>();
            newW.add(w);
            configuration.addDefault(p,newW);

        }
        WorldSender.getPlugin().saveConfig();
    }

}

I planed to code this plugin for my Multiverse based server for easy world navigation.
but my only shows this:

playerName:
- worldName

this is my main:
........................................................

Code:

package me.yuanjv.worldsender;

import org.bukkit.plugin.java.JavaPlugin;

public final class WorldSender extends JavaPlugin {
    public static WorldSender plugin;
    @Override
    public void onEnable() {
        plugin=this;
        getConfig().options().copyDefaults(true);
        getServer().getPluginManager().registerEvents(new Recorder(),this);
        getCommand("worldsend").setExecutor(new Command());
        getCommand("delaytp").setExecutor(new tp());
    }
    public static WorldSender getPlugin(){
        return plugin;
    }
}

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

You cannot modify #getStringList directly. Instead, you should modify one list, then set the list in the config to the modified version of that list.

Code:Java

List<String> list = configuration.getStringList("path");
 
list.remove("old");
list.add("new");
 
configuration.set("path", list);

Also, use #set instead of #addDefault when modifying the section.

 

Thank you so much that works.

if (configuration.contains(p)){
l = configuration.getStringList(p);
for (String name : l) {
if (name.equals(mainW) || name.equals(mainW + "_nether") || name.equals(mainW + "_the_end")) {
old = name;
}
}
List<String> list = configuration.getStringList(p);

list.remove(old);
list.add(w);
configuration.set(p,list);
}else{
List<String> newW= new ArrayList<>();
newW.add(w);
configuration.addDefault(p,newW);

}
WorldSender.getPlugin().saveConfig();

EDIT by Moderator: merged posts, please use the edit button instead of double posting.