一个基本的学生成绩管理系统，有选课，查课，查看成绩，以及导入导出成绩的基本功能，方便了解Java web项目的实现流程。(A basic student performance management system, there are courses, check classes, view the results, as well as import and export results of the basic functions, to facilitate understanding o

java程序常用的工具类。检查对象是否为空，是否数字，是否小数，是否邮箱，自动补零，获取当前时间，获取随机数，字符加密等(Commonly used tool classes for Java programs. Check whether the object is empty, whether the number, whether the decimal, whether the mailbox, automatic zero compensation, access to the cur

用java GUI设计一个游戏，数画面上出现的动物个数，并监听输入，重新生成(When launched, a random number of animal images ranging from 1 to 10 are displayed and the user is expected to enter a number,and click 'check'.)