封装多个集合在一个类中

   public class UserData
    {
        List<Student> stulist = new List<Student>();  //实例化student类型的集合

        public List<Student> Stulist     //设置属性读取
        {
            get { return stulist; }
            set { stulist = value; }
        }
        List<Teacher> tealist = new List<Teacher>();

        public List<Teacher> Tealist
        {
            get { return tealist; }
            set { tealist = value; }
        }
    }

        UserData ud = new UserData();  //实例化封装后的类,调用

        internal UserData Ud   //封装属性，可以不封装，但是推荐封装
        {
            get { return ud; }
            set { ud = value; }
        }