14 在公有类中使用访问方法而非公有域

class Point{
    public double x;
    public double y;
}

class Point{
    private double x;
    private double y;

    Point(double x, double y) {
        this.x = x;
        this.y = y;
    }

    double getX() {
        return x;
    }

    void setX(double x) {
        this.x = x;
    }

    double getY() {
        return y;
    }

    void setY(double y) {
        this.y = y;
    }
}