Loading info in configs into hashmaps

First off here are my HashMaps/ArrayLists

Code:java

 public static List<Player> InFFA = new ArrayList<Player>();
Map<String, Integer> kills = new HashMap<String, Integer>();
ArrayList<String> highkill = new ArrayList<String>();

What I am trying to do is store players killstreaks in a config, and once a week load the highest killstreak int and the player name into a HashMap and get the highest one and display it on a sign.

Code:java

 @EventHandler
public void onkill(PlayerDeathEvent e) {
Player p = (Player)e.getEntity();
Player killer = p.getKiller();
if(Main.InFFA.contains(p) && (Main.InFFA.contains(killer))) {
killer.giveExpLevels(1);
File file = new File("plugins" + File.separator + "Killstreaks" + File.separator + killer.getName());
if(!file.exists()) {
try {
file.createNewFile();
} catch (IOException e1) {
e1.printStackTrace();
}
FileConfiguration config = YamlConfiguration.loadConfiguration(file);
config.set("Name", killer.getName());
config.set("Killstreak", 1);
config.set("HKillstreak", 1);
try{
config.save(file);
}catch(IOException e1){
e1.printStackTrace( ) ;
}
}else{
//this part does nothing, doesnt even leave any stacktrace in console
FileConfiguration config = YamlConfiguration.loadConfiguration(file);
config.set("Killstreak", killer.getLevel());
 
}
}
}

One other thing as well, when I kill my other alt on my main, it creates the config. but when I kill again and my level is 2 and I check the config again. It hasnt changed, also one more thing

Code:java

 private void loadKills() {
File file = new File("plugins" + File.separator + "Killstreaks");
FileConfiguration config = YamlConfiguration.loadConfiguration(file);
if(file.exists()) {
for(String pName : config.getKeys(false)){
 
int kills2 = config.getInt(pName + File.separator + "HKillstreak");
 
kills.put(pName, kills2);
}
 
kills = MapUtil.sortByValue(kills);
 
 
 
for(String s : kills.keySet())
highkill.add(s);
 
//stacktrace says this is line with error
String highestKiller = highkill.get(highkill.size() - 1);
 
int highestKills = kills.get(highestKiller);
 
Bukkit.broadcastMessage(ChatColor.RED + highestKiller + " has the highest killstreak of " + highestKills);
}else{
System.out.println("No Killstreak Folder Found!");
}
}

When I try to run the function, it says that the error is on this line,
String highestKiller = highkill.get(highkill.size() - 1);
Not sure if it is that or something else.
I really do need this so any help ASAP would be MUCH appreciated.
Thanks!

 

Moved to a more appropriate forum.