自己用java写的一个计算器小程序可以进行加减乘除加括号的四则混合运算：加减乘除可以直接实现，加上括号后需要右括号事件来触发（这只是核心代码图形界面自己可以写！）-I use java to write a small programs of calculator　,which cancomplete adds, subtracts, divides add parentheses to the operation of the four mix ： adds, subtracts, divides, and the brackets can be directly completed after closing parenthesis to trigger （ this is the graphical interface you can compile it by yourself! ）