Rubyツアー 1/8: クラス定義 publicclass Circle extends Shape { class Circle < Shape private final int radius; def initialize(radius) public Circle(int radius) { @radius = radius this.radius = radius; end } attr_reader :radius public int getRadius() { def area return radius; Math::PI * (@radius ** 2) } end public double getArea() { end return Math.PI * Math.pow(radius, 2); puts Circle.new(2).area } public s

