Program Motor to Make One Exact Revolution

[r0306]

We're using a 12V Tetrix Motor connected to a spike. Right now, we're trying to program the motor so that it starts and ends in the exact position but it never seems to do so. Please help.

Here is the current code we're using:

            if (leftStick.getRawButton(3))
            {
                              
                    piston.set(Relay.Value.kForward);

                    new java.util.Timer().schedule(new TimerTask() {          
   
                    public void run() {
           
                        piston.set(Relay.Value.kOff);
                            
                   }
             }, 1000L); //motor spins for one second
               
            }