报告内容： 实现两个有理数的相加、相减、相乘、及相除的四则混合运算。-contents of the report : the Rational achieve two together, subtract, multiply, and eliminate the four mixed computing.

在dos下运行的一个简单的关于有理数类的程序，可以学习Java类的基本结构，适合初学者-In the dos run a simple program on rational classes, can learn the basic structure of Java classes for beginners