Bukkit BarAPI example

BukkitScheduler scheduler = Bukkit.getServer().getScheduler(); //Bukkit Scheduler
int countDownTimer=0; //the BukkitScheduler task id
MyPlugin plugin; //the instance of your plugin

int time=60; //your time in seconds

int maxTime=60;

void countDown(final String world) { // the name of your world

    countDownTimer = scheduler.scheduleSyncRepeatingTask(plugin,
            new Runnable() {
                public void run() {

                    // set the Bar
                    float f = time;
                    float percentage = (100 * (f / maxTime));

                    for (Player pl : Bukkit.getWorld(world).getPlayers())
                        BarAPI.setMessage(pl, "Game starts in " + time, percentage);

                    if (time <= 5) {
                        // You can add a "Click" sound here
                    }

                    // when gets to 0
                    if (time <= 0) {
                        scheduler.cancelTask(countDownTimer);

                        for (Player pl : Bukkit.getWorld(world).getPlayers())
                            BarAPI.removeBar(pl);

                        startGame(); // call your desired method
                    }

                    time--;
                }
            }, 20, 20);
}