Cannot refer to a non-final variable inside an inner class defined in a different method

Edited:
I need to change the values of several variables as they run several times thorugh a timer. I need to keep updating the values with every iteration through the timer. I cannot set the values to final as that will prevent me from updating the values however I am getting the error I describe in the initial question below:

I had previously written what is below:

I am getting the error “cannot refer to a non-final variable inside an inner class defined in a different method”.

This is happening for the double called price and the Price called priceObject. Do you know why I get this problem. I do not understand why I need to have a final declaration. Also if you can see what it is I am trying to do, what do I have to do to get around this problem.

public static void main(String args[]) {

    int period = 2000;
    int delay = 2000;

    double lastPrice = 0;
    Price priceObject = new Price();
    double price = 0;

    Timer timer = new Timer();

    timer.scheduleAtFixedRate(new TimerTask() {
        public void run() {
            price = priceObject.getNextPrice(lastPrice);
            System.out.println();
            lastPrice = price;
        }
    }, delay, period);
}