public class Circle implements Drawable { 

    private double center_x_;
    private double center_y_;
    private double radius_;

    private boolean isFilled_;

    Circle(double center_x, double center_y, double radius, boolean isFilled) {
        center_x_ = center_x;
        center_y_ = center_y;
        radius_ = radius;
        isFilled_ = isFilled;
    }

    Circle(double center_x, double center_y, double radius) {
        this(center_x, center_y, radius, true);
    }

    public void draw() {
        if (isFilled_)
            StdDraw.filledCircle(center_x_, center_y_, radius_);
        else
            StdDraw.circle(center_x_, center_y_, radius_);
    }
}