@startuml

class User { - username: String - email: String - age: int - gender: String + User(username: String, email: String, age: int, gender: String) + getUsername(): String + getEmail(): String + getAge(): int + getGender(): String + setUsername(username: String): void + setEmail(email: String): void + setAge(age: int): void + setGender(gender: String): void + toString(): String }

class UserManager { - userList: ArrayList - FILE_NAME: String + UserManager() + readUsersFromFile(): ArrayList + writeUsersToFile(): void + addUser(user: User): void + findUserByUsername(username: String): User + removeUser(username: String): boolean + modifyUserInfo(username: String, newEmail: String, newAge: int, newGender: String): boolean }

User --* UserManager

@enduml