一个JAVA计算器，能够在输出显示屏上显示所输入的式子，并且能够进行4则混和运算。比如：要求（8-4*4）/（4-6） 就只要输入这个式子便可计算出结果。。。

-A JAVA calculator that can display the output screen input formula, and mixing operations can be carried out 4. For example: requirements (8-4* 4)/(4-6) to enter the formula as long as the results can be calculated. . .