18p public class circle{ int radius; String name; public circle(){ radius=1;name=""; } public circle(int r, String n){ radius = r; name=n; } public double getAr(){ return 3.14*radius*radius; } public static void main(String[] args){ circle pizz = new circle(10, "자바피자"); double ar=pizza.getAr(); System.out.println(pizz.name+"의 면적은"+ar); circle donut = new circle(); donut.name="도넛피자"; ar=donut.get..