1.The inverse Polish algorithm is used to compile the calculator Android app, judge the legitimacy of the formula, and realize the functions of addition, subtraction, multiplication, division, brackets and percent sign
2.采用逆波兰算法进行计算器 Android app编写，进行算式的合法性判断，实现了加，减，乘，除，括号，百分号的功能
3.UI很难看
4.只是为了实现计算器功能