Understanding the Distinction: Final Class vs. Record in Java

Introduction

In Java, there are two different ways to create immutable classes: using the final keyword or using the record keyword. While both approaches serve a similar purpose, there are important distinctions between them that developers need to understand to make informed decisions about when to use each.

Final Classes

A final class in Java is one that cannot be subclassed. Once a class is declared as final, it cannot be extended by any other class. This key feature ensures that the class's behavior and implementation remain intact, preventing any unintended modifications or overriding of methods.

Benefits of Final Classes

• Security: Final classes cannot be subclassed, meaning sensitive methods or implementation details cannot be altered by malicious code.

• Performance: Final classes are usually faster than non-final classes, as the JVM can make certain optimizations.

• Design clarity: Final classes explicitly convey that they are not meant to be inherited, allowing for more focused and maintainable code.

Records

Records, introduced in Java 14, provide a convenient way to create immutable classes. The record keyword combines the features of a final class with the added benefit of automatically generating basic implementations of equals(), hashCode(), and toString() methods.

Benefits of Records

• Conciseness: Records significantly reduce boilerplate code by automatically generating common methods.

• Readability: Records enhance code readability by clearly indicating that the class is immutable and contains only data.

• Immutability: Records are inherently immutable, meaning the state of an object cannot change once it is created.

When to Use Final Classes

Use a final class when:

• The class's behavior should not be modified or extended.

• There is a need to prevent inheritance from the class.

• Performance optimizations are required.

When to Use Records

Use records when:

• The primary purpose of the class is to store data.

• Conciseness and readability are important.

• Automatic generation of equals(), hashCode(), and toString() methods is desired.

Conclusion

Understanding the distinction between final classes and record classes is crucial for writing clean, maintainable, and efficient Java code. While both approaches offer immutability, final classes are more suitable when there is a need to prevent subclassing and enhance performance, while records are best used when data storage and automatic method generation are desired.