public class ShapeUtil {
    public static void printArea(Shape shape) {
        System.out.println("图形面积为：" + shape.getArea());
    }

    public static void main(String[] args) {
        Shape circle = new Circle(5);
        Shape rectangle = new Rectangle(4, 6);
        Shape triangle = new Triangle(3, 8);

        printArea(circle);
        printArea(rectangle);
        printArea(triangle);
    }
}