class Shape {
    public void draw() {
        System.out.println("绘制一个图形");
    }
}

class Circle extends Shape {
    @Override
    public void draw() {
        System.out.println("绘制一个圆形 ○");
    }
}

class Rectangle extends Shape {
    @Override
    public void draw() {
        System.out.println("绘制一个矩形 □");
    }
}

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

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

        System.out.println("=== 基础题测试 ===");
        drawShape(circle);
        drawShape(rectangle);

        Shape[] shapes = {new Circle(), new Rectangle(), new Shape()};
        System.out.println("\n遍历数组：");
        for (Shape s : shapes) {
            drawShape(s);
        }
    }
}