publicclassUser{privateString name;privateintage;privateString gender;publicUser(String name,intage, String gender){this.name = name;this.age = age;this.gender = gender;}publicstaticUserpraseFrom(String userInfoText){//将文本("小王&28&男")分析成类User}publicStringformatToText(){//将类User格式化为文本（"小王\t28\t男"）}}publicclassUserFileFormatter{publicvoidformat(String userFile, String formattedUserFile){//此处省略打开文件的代码List users =newArrayList<>();while(1) {//将文件中的数据读取到userTextUser user = User.parseFrom(userText);users.add(user);}//此处省略根据年龄从小到大排序users的代码for(inti =0; i < users.size(); ++i) {String formattedUserText = user.formatToText();//此处省略写入新文件的代码}//此处省略封闭文件的代码}}publicclassMainApplication{publicstaticvoidmain(Sring[] args){UserFileFormatter userFileFormatter =newUserFileFormatter();userFileFormatter.format("/home/zheng/users.txt","/home/zheng/formatted_users.txt");}}