如何从数组列表中删除用户？

package main; import java.util.ArrayList; public class UserGroup { ArrayList userGroup = new ArrayList(); User userOne; public UserGroup() { addUser(new User("lnb1g16", "Student", "Lee")); addUser(new User("hpf1g17", "Staff", "Harry")); addUser(new User("jks1g25", "Student", "Jordon")); } public void addUser(User inUser) { //userGroup.add(new User("LeeB123", "Staff", "Lee")); userGroup.add(inUser); } public ArrayList getUserGroup() { return userGroup; } public void removeFirstUser() { userGroup.remove(0) } } 

我已经尝试创建一个方法，删除第一个用户，似乎正在编译，但实际上并没有在编译程序时删除用户。 关于如何解决这个问题的任何想法都会很棒，谢谢。

调用程序的主要方法

 package main; public class Main{ public static void main(String[] args) { for (int counter=2; counter<=40; counter+=2) { System.out.println(counter); } System.out.println("For loop complete."); int counter = 1; int increment = 2; int loopexeccounter = 0; while (counter <= 500) { loopexeccounter = loopexeccounter + 1; System.out.println(counter); counter = counter + increment++; } System.out.print("This loop iteratted "+loopexeccounter+" times.\n"); { //public User callUserGroup; UserGroup userGroupObject = new UserGroup(); for (User curUser : userGroupObject.getUserGroup()) { System.out.println(curUser.toString()); } } } } 

用于声明用户详细信息的方法

 package main; class User { String username; String userType; String name; User(String username, String userType, String name) { this.username = username; this.userType = userType; this.name = name; } public String getUsername() { return username; } public String getUserType() { return userType; } public String getName() { return name; } public String setUserType(String admin) { return userType = admin; } @Override public String toString() { return username + " " + userType; } } 

Answer 1

它运作良好：

 ` public static void main(String[] args) { UserGroup MyUser = new UserGroup(); for (User curUser : MyUser.getUserGroup()) { System.out.println(curUser.toString()); } MyUser.removeFirstUser(); System.out.println("your user removed!"); for (User curUser : MyUser.getUserGroup()) { System.out.println(curUser.toString()); } }` 

结果：

 `User@4554617c 1 User@74a14482 2 User@1540e19d 3 your user removed! User@74a14482 1 User@1540e19d 2`