public class ShapeTest {
    public static void main(String[] args) {
        // 创建各个图形对象
        Shape c = new Circle(5);
        Shape r = new Rectangle(4,6);
        Shape t = new Triangle(3,4);

        //统一调用工具打印面积
        System.out.print("圆形：");
        ShapeUtil.printArea(c);

        System.out.print("矩形：");
        ShapeUtil.printArea(r);

        System.out.print("三角形：");
        ShapeUtil.printArea(t);
    }
}