Untitled

public class Decrementer {
    private void decrement(Double x) {
        x = x - 1.0;
    }
    public static void main(String[] args) {
        Double x = 12.3;
        Decrementer decrementer = new Decrementer();
        decrementer.decrement(x);
        System.out.println(x);
    }
}