When and Why Should You Use a `final` Class in Java?

Understanding the Purpose of "final class" in Java

In Java, it is possible to declare a class as final, which prevents it from being extended. While this concept may seem counterintuitive to object-oriented programming, it offers specific benefits and limitations.

Why Use a Final Class?

Contrary to popular belief, declaring a class as final does not imply that all references to its objects are final. Instead, it indicates that the class cannot be extended or inherited by other classes. This feature is typically used when:

• It is crucial to prevent the implementation details of a class from being modified or overridden by subclasses.
• The class encapsulates core system functionality that should not be modified.
• Security or performance concerns require the prevention of certain types of modification.

Limitations of Final Classes

While final classes offer advantages, they also impose limitations:

• Subclasses cannot inherit the functionality of the final class.
• Extensions or modifications to the final class are not possible.
• Object-oriented principles that encourage code reuse and flexibility may be hindered.

When to Use a Final Class

Programmers typically use final classes in scenarios such as:

• Defining low-level classes that provide foundational functionality (e.g., String, Integer).
• Implementing classes that interact directly with sensitive system resources.
• Creating classes that enforce strict adherence to specific protocols or interfaces.
• Preventing accidental inheritance or code modifications that could introduce bugs.

Impact on Object-Oriented Characteristics

Declaring a class as final does not completely invalidate its status as an object. Objects of final classes retain their ability to:

• Encapsulate state and behavior.
• Interact with other objects through methods.
• Be constructed, inherited, and disposed of as needed.

However, final classes limit the inheritance principle of object-oriented programming, as they cannot be used as base classes for extension. In cases where inheritance is not essential, this limitation can provide benefits such as improved code stability and reduced complexity.

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