堆栈类的JAVA描述，通过此程序可清楚的了解到堆栈的性质，并学习了JAVA-stack JAVA category described by this procedure can clearly understand the nature of the stack and learning JAVA

功能最全的能够运行四则运算的计算器且利用堆栈实现带括号的功能-The most versatile able to run the calculator and the four operations with the use of the stack to achieve the function in parentheses