keyExercise3_5.java

public class keyExercise3_5 {
    public static void main(String[] args) {
        Circle c = new Circle(1,2, 5);

        c.setX(4);
        c.setY(5);
        c.setRadius(6);
        System.out.println("x      : " + c.getX());
        System.out.println("y      : " + c.getY());
        System.out.println("radius : " + c.getRadius());
        System.out.println("area   : " + c.getArea());

        c.setRadius(-5);
        System.out.println("radius : " + c.getRadius());
        c = new Circle(1, 1, -4);
        System.out.println("radius : " + c.getRadius());

    }

    public static class Circle {
        private int x;
        private int y;
        private double radius;

        public Circle(int x, int y, double radius) {
            setX(x);
            setY(y);
            setRadius(radius);
        }

        public void setRadius(double radius) {
            this.radius = Math.max(radius, 0);
        }

        public void setX(int x) {
            this.x = x;
        }
        public void setY(int y) {
            this.y = y;
        }
        public int getX() {
            return x;
        }
        public int getY() {
            return y;
        }
        public double getRadius() {
            return radius;
        }
        public int getArea(){
            double area = Math.PI * Math.pow(radius, 2);
            return (int)area;
        }

    }
}