使用Java写一个（一）系统功能说明 1、 用户管理系统主要功能：普通用户和管理员用户功能。 2、 普通用户：可以查看全部用户信息，按用户年龄查看个人信息、修改自己的信息；可以尝试增加按照名字查看个人信息。 3、 管理员：删除用户、增加用户、修改用户、按ID查看用户、查看全部信息。可以尝试增加按照名字查看个人信息。 4、 用户的实体类的特征:用户ID编号、用户名、用户密码、家庭地址、年龄、电话等 （二）实现说明： 1．定义User类，用户ID编号、用户名、用户密码、家庭地址、年龄、电话、是否管理员。定义有参和无参的两个构造方法，定义toString()方法方便打印对象信息。 2.系统中定义UserDAO类，定义密码错误次数属性成员；定义以下成员方法：查看全部用户信息、按用户年龄查看个人信息、按名字查看用户信息、按照ID查看信息、根据用户名以及密码修改用户的信息、根据用户编号修改信息、删除用户、增加用户、根据用户名和密码登陆的功能。 3、模拟数据存储使用类Memoery中的userlist数组实现。该类中定义长度为100的User类型的静态数据成员，用于存放数据信息；定义用于描述数组中元素个数的静态数据成员；为了模拟实现数据存储，定义不含参数的构造函数，实现通过定义若干用户对象初始化数组成员中的一部分，其余成员也初始化为user对象，仅为对象是否管理员赋值为false。 4.定义Test类，在main方法中实现功能操作。要注意能循环操作，即输入用户名和密码一次，能进行多种功能。使用循环语句实现。

好的，以下是Java实现：

User类：

public class User {
    private int id;
    private String name;
    private String password;
    private String address;
    private int age;
    private String phone;
    private boolean isAdmin;

    public User() {
        this.id = -1;
        this.name = "";
        this.password = "";
        this.address = "";
        this.age = -1;
        this.phone = "";
        this.isAdmin = false;
    }

    public User(int id, String name, String password, String address, int age, String phone, boolean isAdmin) {
        this.id = id;
        this.name = name;
        this.password = password;
        this.address = address;
        this.age = age;
        this.phone = phone;
        this.isAdmin = isAdmin;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public boolean isAdmin() {
        return isAdmin;
    }

    public void setAdmin(boolean isAdmin) {
        this.isAdmin = isAdmin;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", password='" + password + '\'' +
                ", address='" + address + '\'' +
                ", age=" + age +
                ", phone='" + phone + '\'' +
                ", isAdmin=" + isAdmin +
                '}';
    }
}

UserDAO类：

public class UserDAO {
    private static int passwordErrorCount = 0;
    private static int elementCount = 0;
    private static final int MAX_SIZE = 100;
    private static User[] userList = new User[MAX_SIZE];

    static {
        userList[0] = new User(0, "admin", "admin", "北京市", 30, "123456789", true);
        userList[1] = new User(1, "user1", "123456", "上海市", 20, "987654321", false);
        userList[2] = new User(2, "user2", "123456", "广州市", 25, "123123123", false);
        elementCount = 3;
    }

    public static void showAllUsers() {
        for (int i = 0; i < elementCount; i++) {
            System.out.println(userList[i]);
        }
    }

    public static void showUserByAge(int age) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getAge() == age) {
                System.out.println(userList[i]);
            }
        }
    }

    public static void showUserByName(String name) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getName().equals(name)) {
                System.out.println(userList[i]);
            }
        }
    }

    public static void showUserById(int id) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getId() == id) {
                System.out.println(userList[i]);
                return;
            }
        }
        System.out.println("User not found.");
    }

    public static boolean login(String name, String password) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getName().equals(name) && userList[i].getPassword().equals(password)) {
                passwordErrorCount = 0;
                return true;
            }
        }
        passwordErrorCount++;
        System.out.println("Wrong username or password. You have " + (3 - passwordErrorCount) + " chances left.");
        return false;
    }

    public static void modifyUserByNameAndPassword(String name, String password, String address, int age, String phone) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getName().equals(name) && userList[i].getPassword().equals(password)) {
                userList[i].setAddress(address);
                userList[i].setAge(age);
                userList[i].setPhone(phone);
                System.out.println("User info modified successfully.");
                return;
            }
        }
        System.out.println("Wrong username or password.");
    }

    public static void modifyUserById(int id, String name, String password, String address, int age, String phone) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getId() == id) {
                userList[i].setName(name);
                userList[i].setPassword(password);
                userList[i].setAddress(address);
                userList[i].setAge(age);
                userList[i].setPhone(phone);
                System.out.println("User info modified successfully.");
                return;
            }
        }
        System.out.println("User not found.");
    }

    public static void deleteUserById(int id) {
        for (int i = 0; i < elementCount; i++) {
            if (userList[i].getId() == id) {
                for (int j = i; j < elementCount - 1; j++) {
                    userList[j] = userList[j + 1];
                }
                userList[elementCount - 1] = null;
                elementCount--;
                System.out.println("User deleted successfully.");
                return;
            }
        }
        System.out.println("User not found.");
    }

    public static void addUser(String name, String password, String address, int age, String phone) {
        if (elementCount == MAX_SIZE) {
            System.out.println("User list is full, cannot add more users.");
            return;
        }
        userList[elementCount] = new User(elementCount, name, password, address, age, phone, false);
        elementCount++;
        System.out.println("User added successfully.");
    }
}

Memoery类：

public class Memoery {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String name = "";
        String password = "";
        while (true) {
            System.out.print("Please enter your name: ");
            name = scanner.nextLine();
            System.out.print("Please enter your password: ");
            password = scanner.nextLine();
            if (UserDAO.login(name, password)) {
                break;
            }
            if (UserDAO.passwordErrorCount == 3) {
                System.out.println("Too many password errors, program exits.");
                return;
            }
        }

        while (true) {
            System.out.println("Please select the function you want to use:");
            System.out.println("1. Show all users");
            System.out.println("2. Show user by age");
            System.out.println("3. Show user by name");
            System.out.println("4. Show user by ID");
            System.out.println("5. Modify user info by name and password");
            System.out.println("6. Modify user info by ID");
            System.out.println("7. Delete user by ID");
            System.out.println("8. Add user");
            System.out.println("0. Exit");
            System.out.print("Your choice: ");
            int choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 1:
                    UserDAO.showAllUsers();
                    break;
                case 2:
                    System.out.print("Please enter the age: ");
                    int age = scanner.nextInt();
                    scanner.nextLine();
                    UserDAO.showUserByAge(age);
                    break;
                case 3:
                    System.out.print("Please enter the name: ");
                    String userName = scanner.nextLine();
                    UserDAO.showUserByName(userName);
                    break;
                case 4:
                    System.out.print("Please enter the ID: ");
                    int id = scanner.nextInt();
                    scanner.nextLine();
                    UserDAO.showUserById(id);
                    break;
                case 5:
                    System.out.print("Please enter the address: ");
                    String address = scanner.nextLine();
                    System.out.print("Please enter the age: ");
                    int userAge = scanner.nextInt();
                    scanner.nextLine();
                    System.out.print("Please enter the phone: ");
                    String phone = scanner.nextLine();
                    UserDAO.modifyUserByNameAndPassword(name, password, address, userAge, phone);
                    break;
                case 6:
                    System.out.print("Please enter the ID: ");
                    int userId = scanner.nextInt();
                    scanner.nextLine();
                    System.out.print("Please enter the name: ");
                    String userName2 = scanner.nextLine();
                    System.out.print("Please enter the password: ");