（1）　　编写一个代表圆柱体的Cylinder类，该类是Circle类的子类。Cylinder类包括圆柱体的高度变量height以及计算圆柱体的体积方法volume()和计算表面积的方法surfaceArea()。

（2）　　编写测试Cylinder类的CylinderTest类，并在该类得main方法中调用Cylinder类的相关方法。

（3）　　重写Point和Circle类的equals()、toString()方法，并测试这些方法的正确性。

-(1) the preparation of a representative cylinder of the Cylinder class, such is the Circle class subclass. Cylinder cylinder type, including a high degree of variable height, as well as methods of calculating the size of cylinder volume () method and calculation of surface area surfaceArea (). (2) the preparation of test Cylinder class CylinderTest category, and in such a main method to call the relevant methods Cylinder category. (3) rewrite the Point and Circle class equals (), toString () method, and test the correctness of these methods.