java增删改查不用数据库

import java.util.ArrayList;
import java.util.List;

class User {
    private String id;
    private String name;

    public User(String id, String name) {
        this.id = id;
        this.name = name;
    }

    // Getters and Setters
}

public class InMemoryCRUD {
    private List<User> users = new ArrayList<>();

    // Create
    public void addUser(User user) {
        users.add(user);
    }

    // Read
    public User getUserById(String id) {
        for (User user : users) {
            if (user.getId().equals(id)) {
                return user;
            }
        }
        return null;
    }

    // Update
    public boolean updateUser(User user) {
        for (int i = 0; i < users.size(); i++) {
            if (users.get(i).getId().equals(user.getId())) {
                users.set(i, user);
                return true;
            }
        }
        return false;
    }

    // Delete
    public boolean deleteUser(String id) {
        for (int i = 0; i < users.size(); i++) {
            if (users.get(i).getId().equals(id)) {
                users.remove(i);
                return true;
            }
        }
        return false;
    }

    public static void main(String[] args) {
        InMemoryCRUD crud = new InMemoryCRUD();
        crud.addUser(new User("1", "Alice"));
        System.out.println(crud.getUserById("1").getName());
        crud.updateUser(new User("1", "Alicia"));
        System.out.println(crud.getUserById("1").getName());
        crud.deleteUser("1");
        System.out.println(crud.getUserById("1")); // Should print null
    }
}