TimeDetectionTask

public void onEnable() {
  createRunnable().runTaskTimerAsynchronously(this,
                20-(Bukkit.getWorld("world").getTime() % 20), 20);
}


private BukkitRunnable createRunnable() {
        long threshold = 18; //Incase a skip happens we have this.
        long activateAt = 16000; //What Minecraft time to activate this at.

        return (new BukkitRunnable() {
            long prevTime = -1; //Checking for time skips/sleeping
            @Override
            public void run() {
                if((Bukkit.getWorld("world").getTime() % 20) != 0) {//Check if it got out of sync (from a command or something)
                    cancel();
                    createRunnable().runTaskTimerAsynchronously(MainClassExtendsJavaPlugin.this,
                            20-(Bukkit.getWorld("world").getTime() % 20), 20);//Reschedule the task
                    return;
                }
                if(!(prevTime == -1 || Bukkit.getWorld("world").getTime() - prevTime >= threshold)//Check if time jumped(from sleeping or other)
                        || (Bukkit.getWorld("world").getTime() == activateAt)) {//Check if the time is the activation time
                    onActivate();
                    prevTime = -1;//Reset the skip check time
                    return;
                }
                prevTime = Bukkit.getWorld("world").getTime(); //Update the skipChecktime
            }
            /**
            This is run whenever the worldtime is the same as ActivateAt time or when someone sleeps/time skips
             */
            private void onActivate() {
                //Code here
                System.out.println("Nighttime!");
            }

        });
    }