//For TestCircle.java

public class TestCircle {
    public static void main(String[] args) {
		
        Circle circle = new Circle(5);

        System.out.printf("Radius of the circle: %.2f%n", circle.getRadius());
        System.out.printf("Area of the circle: %.2f%n", circle.calculateArea());
        System.out.printf("Perimeter of the circle: %.2f%n%n", circle.calculatePerimeter());

        circle.setRadius(7);
        System.out.printf("Radius of the circle: %.2f%n", circle.getRadius());
        System.out.printf("Area of the circle: %.2f%n", circle.calculateArea());
        System.out.printf("Perimeter of the circle: %.2f%n%n", circle.calculatePerimeter());
		
        circle.setRadius(-3);
    }
}

///////////////////////////////////////////////////////////////////////////////////////////
//For Circle.java
///////////////////////////////////////////////////////////////////////////////////////////

public class Circle {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    public double getRadius() {
        return radius;
    }

    public void setRadius(double radius) {
        if (radius > 0) {
            this.radius = radius;
        } else {
            System.out.println("Radius must be greater than 0");
        }
    }

    public double calculateArea() {
        return Math.PI * radius * radius;
    }

    public double calculatePerimeter() {
        return 2 * (Math.PI * radius);
    }
}