Best way to add a cool-down time?

So if I want to add a cool-down time to /derp for a player, what is the best way to do that? I currently have it working using a Timer and TimerTasks, but it isn't efficient at all and I'm pretty sure there is a better way to do it.

 

Why not use a HashMap<Player, Long> and save System.currentTimeMilis() in it every time the command is executed??
Then just check if(!hashMap.containsKey(player) || ((System.currentTimeMilis() - hashMap.get(player)) >= INTERVAL))

INTERVAL is number of miliseconds (1/1000th of second)
If not, give them error message.

 

I'm using the same method to prevent that a block of code is executed during an event too often.
It turned out to be the most reliable one.

 

What @Acrobot suggested is what I use most often, though you can also apply the same concept with the Scheduler. (I'm really not sure which is better, but I use both just to dabble in each area)