Trouble Updating Plugin

Hello, im trying to update SkyrimRPG and ive got it all done but there are a few problems.

onPlayerQuit and event is called that saves the players current perks but this doesnt work anymore and this code is very outdated it seems.

Code:

public void savePerks(Player player)
 {
 File file = new File(this.p.getDataFolder().getPath());
    if (!file.exists()) file.mkdir();
 File perks = new File(file.getPath() + File.separator + "Perks");
   if (!perks.exists()) perks.mkdir();
    File plist = new File(perks.getPath() + File.separator + player.getName() + ".txt");
 try
   {
     if (!plist.exists())
   {
     FileOutputStream fos = new FileOutputStream(plist);
     fos.flush();
  fos.close();
  }
   BufferedWriter bw = new BufferedWriter(new FileWriter(plist));
 bw.write("#Don't edit this unless you like errors");
    bw.newLine();
    for (Perk p : ((perks).get(player).keySet()))
   {
      bw.write(p.toString() + "," + ((HashMap)this.perks.get(player)).get(p));
    bw.newLine();
 }
    bw.flush();
      bw.close();
    }
   catch (IOException ioe)
  {
    this.p.log.severe("[SkyrimRPG]COULD NOT SAVE \"" + player.getName() + "\"'s PERKS!!!");
  }
  }

This line:

Code:

for (Perk p : ((perks).get(player).keySet()))

No longer works and im not very good with Files so can you show me a work around?

 

can you please tell us what the definition of perks is ?
at a guess perks is a HashMap<Player,HashMap<Perk,?>>

 

Player objects will break this a lot.