New to Java

H, I have the code:

int delay = 0; .
int period = 5; 
Timer timer = new Timer();
//...
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {	
Calcule();
SchimbaPeriod();
repaint();			
}
}, delay, period);
//...
public void SchimbaPeriod()
{period=period+r.nextInt(3) - 1;
if (period==3) period=4; 
if (period==21) period=20;
}

But that dosnt change speed of timer, probably because it takes period only when timer is initiated.
What would be the way to that?