用JAVA编写 声明一个基类Shape,在此基础上派生出Rectangle和Circle,二者都有GetArea()函数计算对象的面积.

public class Test{ public static void main(String args[]){ Shape rectangle = new Rectangle(3, 5);//长3宽5长方形 double rectangleArea = rectangle.getArea(); System.out.println("长3宽5的长方形面积是:" + rectangleArea); Circle c = ne