java/w5/MainFiveBasic.java

public class MainFiveBasic {
    public static abstract class Shape {
        public abstract void draw();
    }

    public static class Circle extends Shape {
        private final Double radius;

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

        public void draw() {
            System.out.println("Drawing a circle of radius " + radius);
        }
    }

    public static class Rectangle extends Shape {
        private final Double side1;
        private final Double side2;

        public Rectangle(Double side1, Double side2) {
            this.side1 = side1;
            this.side2 = side2;
        }

        public void draw() {
            System.out.println("Drawing a rectangle of " + side1 + " * " + side2);
        }
    }

    public static void drawShape(Shape s) {
        s.draw();
    }

    public static void main(String[] args) {
        Shape circle = new Circle(1.23);
        Shape rectangle = new Rectangle(1.23, 4.56);

        drawShape(circle);
        drawShape(rectangle);
    }
}