I can't cancel static scheduler

Forgive my bad English
No achievement cancel a task within a static method . Please help.

Code:

private static int c;
      
        public static void BoardLobby(final Player p) {
            c = Bukkit.getServer().getScheduler().scheduleSyncRepeatingTask(a.plugin, new Runnable() {
              public void run() {
                    if(ScoreboardBooleans.ON_LOBBY == "on") {
                            BoardLobbyUpdate(p);
                        }
                        else     {
                            a.plugin.getServer().getScheduler().cancelTask(c); // no cancel task
                            for(String p : list.ple) {
                            ScoreboardManager sbm = Bukkit.getScoreboardManager();
                            Bukkit.getPlayer(p).setScoreboard(sbm.getNewScoreboard());
                            }
                        }
                    }
                }, (long) (20*0.8), (long) (20*0.8));

 

Either create a method in the class to cancel the task or use a BukkitRunnable instead of the .getScheduler().schedule ... thing

 

What is line 6 supose to do? is it comparing two strings with == ?
Keep in mind that object comparason with == is only gonna work safely for Singleton objects!