// 父类Shape
class Shape {
    public void draw() {
        // 默认实现
    }
}

// 子类Circle
class Circle extends Shape {
    public void draw() {
        System.out.println("Drawing a circle");
    }
}

// 子类Rectangle
class Rectangle extends Shape {
    public void draw() {
        System.out.println("Drawing a rectangle");
    }
}

// 测试类
class ShapeTest {
    // drawShape方法
    public static void drawShape(Shape shape) {
        shape.draw();
    }
    
    public static void main(String[] args) {
        Circle circle = new Circle();
        Rectangle rectangle = new Rectangle();
        
        drawShape(circle);
        drawShape(rectangle);
    }
}