public class Circle {
double radius;
Circle() {
radius = 10;
}
Circle(double radius) {
this.radius = radius;
}
double Area() {
return Math.PI * this.radius * this.radius ;
}
double Perimeter() {
return 2 * Math.PI * this.radius;
}
void set_radius(double radius) {
this.radius = radius;
}
public static void main(String args[]) {
Circle circle1 = new Circle();
System.out.println(circle1.Area());
System.out.println(circle1.Perimeter() + "\n");
Circle circle2 = new Circle(30);
System.out.println(circle2.Area());
System.out.println(circle2.Perimeter());
}
}
/*
run:
314.1592653589793
62.83185307179586
2827.4333882308138
188.49555921538757
*/
