Solved Efficient way to check all duplicate IPs

Hey,

I'm trying to make a method that returns a list of all players with more than 'x' alts on a given server (an alt being an account on the same IP as another). Currently, I have:

Code:

public static List<String> checkAlts(int limit) {
        Map<String, Integer> alts = new HashMap<>();
        for (Player p : Bukkit.getOnlinePlayers()) {
            if (!alts.containsKey(p.getAddress().getHostName())) {
                alts.put(p.getAddress().getHostName(), 1);

                } else {
                    alts.replace(p.getAddress().getHostName(), alts.get(p.getAddress().getHostName()) + 1);
                }
            }
        alts.values().removeIf(entries -> entries < limit);

        List<String> names = new ArrayList<>();
        for (Player p : Bukkit.getOnlinePlayers()) {
            if (alts.containsKey(p.getAddress().getHostName())) {
                names.add(p.getName());
                alts.remove(p.getAddress().getHostName());
            }
        }
        return names;
    }

This method causes extreme lag and has caused my server to nearly crash twice. Is there a better way to go about doing this that I'm overlooking?

 

Maybe I don't understand exactly what you want to do, but if the idea is just to find who has the same IP, an alternative would be to do:

Code:

@Override
public boolean onCommand(CommandSender sender, Command cmd, String label, String[] args) {
  Map<String, List<String>> connections = new HashMap<>();
  for (Player p : getServer().getOnlinePlayers()) {
    String ip = p.getAddress().getHostName();
    List<String> people = connections.containsKey(ip)?connections.get(ip):new ArrayList<>();
    people.add(p.getName());
    connections.put(ip, people);
  }

  for (Map.Entry<String, List<String>> data : connections.entrySet()) {
    if (data.getValue().size() == 1) continue;

    sender.sendMessage(ChatColor.translateAlternateColorCodes('&', "&7[&a" + data.getValue().size() + "&7][&a" + data.getKey() + "&7]: &6" + String.join("&7,&6 ", data.getValue())));
  }
  return true;
}