本例实现了简单计算器代码，具备加减乘除和正弦功能，旨在抱砖引玉。熟悉java的同学，可以在此基础上实现更复杂的功能。-This example implements a simple calculator code, with addition, subtraction and sine function, designed to hold the brick in jade. Students are familiar with java, more complex functions can be achieved on this basis.