User Profiles: Mutability vs Immutability (JavaBasics_Task_404_V0.1)

📖 Description

In profile management systems, distinguishing between active (modifiable) and archived (read-only) records is crucial for data consistency. This project highlights the Structural Differences between Regular Classes and Records. We implement a FlexibleUser class with setters to allow state changes and a FixedUser record to enforce strict immutability. This comparison demonstrates how records protect data from modification, whereas regular classes provide the flexibility needed for dynamic updates.

📋 Requirements Compliance

• Mutable State: Implemented a standard class with setters for name and age.
• Immutable Contract: Used a record to ensure fields are final and setters are absent.
• Compile-time Safety: Verified that records block any attempt to change their components.

🚀 Architectural Stack

• Java 16+ (Classes, Records, Mutability Patterns)

🏗️ Implementation Details

• FlexibleUser: A standard Java class with a constructor, getters, and setters.
• FixedUser: A record providing a fixed data snapshot.
• ProfileComparisonApp: The entry point for testing mutability limits.

📋 Expected result

*** The code will not compile if lines attempting to modify the record are active.

Flexible profile (before): FlexibleUser[name=Greg, age=30]
Flexible profile (after): FlexibleUser[name=Piter, age=25]
Fixed profile (record): FixedUser[name=Hana, age=28]

💻 Code Example

Project Structure:

JavaBasics_Task_404/
├── src/
│   └── com/yurii/pavlenko/
│                 ├── app/
│                 │   └── ProfileComparisonApp.java
│                 └── profiles/
│                     └── models/
│                         ├── FlexibleUser.java
│                         └── FixedUser.java
├── LICENSE
├── TASK.md
├── THEORY.md
└── README.md

Code

package com.yurii.pavlenko.app;

import com.yurii.pavlenko.profiles.models.FlexibleUser;
import com.yurii.pavlenko.profiles.models.FixedUser;

public class ProfileComparisonApp {

    public static void main(String[] args) {

        FlexibleUser flexible = new FlexibleUser("Greg", 30);
        System.out.println("Flexible profile (before): " + flexible);

        flexible.setName("Piter");
        flexible.setAge(25);
        System.out.println("Flexible profile (after): " + flexible);

        FixedUser fixed = new FixedUser("Hana", 28);
        System.out.println("Fixed profile (record): " + fixed);

        /*
         * UNCOMMENTING THE LINES BELOW WILL CAUSE COMPILATION ERRORS:
         * * fixed.setName("Mary"); // Error: method not found
         * fixed.age = 29;        // Error: field is final
         */
    }
}

package com.yurii.pavlenko.profiles.models;

public record FixedUser(String name, int age) {
}

package com.yurii.pavlenko.profiles.models;

public class FlexibleUser {
    private String name;
    private int age;

    public FlexibleUser(String name, int age) {
        this.name = name;
        this.age = age;
    }

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

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

    @Override
    public String toString() {
        return "FlexibleUser[name=" + name + ", age=" + age + "]";
    }
}

⚖️ License

This project is licensed under the MIT License.

Copyright (c) 2026 Yurii Pavlenko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files...

License: MIT