/*做一个抽象的shape类 有一个可计算面积的抽象方法 1.做矩形和圆形两个类继承shape类 各自计算面积 2.根据两种图形的面积求法各自设置成员变量 3.设置图形类 包含图形名字和一个shape类型的成员 变量 并含一个方法 实现shape类成员的面积操作 4.做一测试类 分别根据不同的shape类对象实现多态*/-/* Do an abstract shape class has a way to calculate the size of an abst

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