public class Price{

    final static Price INSTANCE = new Price(2.8);

    static double initPrice = 20;

    double currentPrice;

    public Price(double discount){

        currentPrice = initPrice - discount;

    }

}

public class Main {

    public static void main(String[] args) {

        System.out.println(Price.INSTANCE.currentPrice);

        Price p = new Price(2.8);

        System.out.println(p.currentPrice);

    }

}