设计一个描述二维平面上点的类Position，该类需要描述点的横坐标和纵坐标，并提供访问器方法（set方法和get方法）和计算两点间距离的方法。写一个程序测试这个类-Design of a two-dimensional plane descr iption class Position point, the class needs to describe the point of abscissa and ordinate and provide accessor methods (set and get methods) and methods to calculate the distance between two points. Write a program to test this class