说明：  Writetxt.java是一个向txt文本文档写入数据的类，有两个参数file和txt,分别 代表要写入的文件名和数据。 DisplaySysTime.java是一个调用系统实时时间的线程类
(Writetxt.java is a text document written to the txt data type, there are two parameters file and txt, representing the need to write the file name and data. DisplaySysTime.java is a time to call real-time thread type)