1 import lombok.Data;
2 
3 @Data
4 public class User {
5     private long id;
6     private String userName;
7     private String password;
8     private String name;
9 }

1 User[] user = new User[20];
2 for (int i=0; i<user.length; ++i){
3 　　user[i] = new User();
4 }

1 List<User> list = new ArrayList<User>();
2 list.add(user);

 1 第一种：
 2     List<User> list = new ArrayList<User>();
 3     UserDao1 userDao1 = new UserDao1();
 4     list = userDao1.selectUserByAll();
 5     Iterator<User> it = list.iterator(); //list集合可以通过迭代器进行遍历
 6     while (it.hasNext()){
 7         System.out.println(it.next());
 8     }
 9 第二种：
10     List<User> list = new ArrayList<User>();
11     UserDao1 userDao1 = new UserDao1();
12     list = userDao1.selectUserByAll();
13     for (User user:list){
14         　System.out.println(user);
15     }
16 第三种：
17     List<User> list = new ArrayList<User>();
18     UserDao1 userDao1 = new UserDao1();
19     list = userDao1.selectUserByAll();
20     for (int i=0; i<list.size(); ++i){
21         System.out.println(list.get(i));
22     }