Geometric Object: Circle

/**
 * Author: Muhammad Fahmi I.
 * Github: github.com/miun173
 * Year: 2018
 */

interface GeometriObject{
	double getPerimeter();
    double getArea();

    // ini juga bisa
    // public double getPerimeter();
	// public double getArea();
}

/**
 * Circle: accept radius 
 */
class Circle implements GeometriObject {
    protected Double radius = 1.0;
    
    public Circle(double radius) {
        this.radius = radius;
    }

    @Override
    public double getPerimeter() {
        return 2*3.14*this.radius;
    }

    @Override
    public double getArea() {
        return 3.14*(this.radius*this.radius);
    }
}

interface Resizable{
    public void resize(int percent);

    // ini juga bisa
	// void resize(int percent);    
}

/**
 * Circle that can be resize based on it's raidus
 */
class ResizableCircle extends Circle implements Resizable {
    public ResizableCircle(Double radius) {
        super(radius);
    }
    
    // Resize the circle radius by percentage
    @Override
    public void resize(int percentage) {
        super.radius = super.radius * percentage/100.0;
    }
}

class Test {
    public static void main(String[] args) {
        ResizableCircle rc = new ResizableCircle(10.0);
        System.out.println("Keliling gelang = " + rc.getPerimeter());
        System.out.println("Luas gelang = " + rc.getArea());

        System.out.println("====setealah resize 20%====");
        
        rc.resize(20);
        System.out.println("Keliling gelang = " + rc.getPerimeter());
        System.out.println("Luas gelang = " + rc.getArea());
    }
}