public Cube(double hight, double sum, double lengh_diag){ // первый конструктор
        this.hight = hight;
        this.setName("Куб");
        this.sum = sum;
        this.lengh_diag = lengh_diag; 
        this.area = hight*hight*6;
        this.volume = hight*hight*hight;

    }