public class Main extends JavaPlugin implements Listener {

    private boolean titlechanged;

    @Override
    public void onEnable() { this.getServer().getPluginManager().registerEvents(this, this);

    new BukkitRunnable() {

        @Override
        public void run() {
            PacketPlayOutPlayerListHeaderFooter packet = new PacketPlayOutPlayerListHeaderFooter();
            Object header1 = new ChatComponentText("§bReberion Network \n §6Survival Games §r|§6 FFA §r|§6 Clans");
            Object header2 = new ChatComponentText("§fReberion Network \n §6Survival Games §r|§6 FFA §r|§6 Clans");

            Object footer = new ChatComponentText("§cPlayers Online: §e" + Bukkit.getServer().getOnlinePlayers().size());
            if(titlechanged) {
                a.set(packet, header1);
                titlechanged = false;
            }else {
                a.set(packet, header2);
                titlechanged = true;
            }
            Field a = packet.getClass().getDeclaredField("a");
            a.setAccessible(true);
            Field b = packet.getClass().getDeclaredField("b");
            a.setAccessible(true);

            a.set(packet, header);
            a.set(packet, footer);

            for(Player player: Bukkit.getOnlinePlayers()) {
            ((CraftPlayer)player).getHandle().playerConnection.sendPacket(packet);
            }

        } catch (NoSuchFieldException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        }
    }.runTaskTimer(this, 0, 20);


    }

    }