本练习制作计算器的实例，运用了Java2 的图形界面技术和消息响应技术。通过图形界

面技术。制作了计算器的用户界面。通过消息响应技术，实现响应用户的操作的功能，最终实现人机交互。

-Examples of this exercise produced calculator, use Java2 graphical interface and message response technology. Through the graphical interface technology. Produced the calculator' s user interface. Message response, the response function of the user' s operation, and ultimately the human-computer interaction.