Understanding the ‘final’ Keyword in Java

The final keyword in Java is a non-access modifier that can be applied to variables, methods, and classes. Understanding its role and implications is crucial for Java developers to ensure cleaner, more reliable code. In this article, we will explore various aspects of the final keyword, including its uses and behaviors in different contexts.

Final Variables

When the final keyword is applied to a variable, it effectively makes that variable a constant, meaning that its value cannot be changed once it is initialized. This can be applied to instance variables, static variables, and local variables.

  • Final Instance Variables: Must be initialized at the time of declaration or in the constructor.
  • Final Static Variables: Usually initialized at the time of declaration and commonly known as constants. These are static members of the class.
  • Final Local Variables: Once assigned a value, it cannot be changed and remains in effect for the duration of the block of code in which it is defined.

Final Methods

A final method in Java cannot be overridden by subclasses. This is particularly useful when you want to prevent any alteration in the behavior of the method, ensuring the intended functionality remains intact across different environments and subclasses.

Final Classes

When a class is declared as final

The Importance of the ‘final’ Keyword

The final keyword is crucial for several reasons:

  • Immutability: Making a class or variable final can be a crucial aspect in creating immutable structures in Java, similar to the String class.
  • Thread Safety: Final variables are inherently thread-safe as their state cannot change once set.
  • Maintenance and Operation Safety: Final methods prevent subclasses from altering base class logic, which can be crucial for maintaining consistent behavior in inherited methods.

Examples of the ‘final’ Keyword in Use

Here are some examples to illustrate how final can be used in Java programming:

// Final variable example
final int LIMIT = 5;

// Final method example
public final void display() {
  System.out.println(This method cannot be overridden.);

// Final class example
public final class Example {
  // Implementation goes here

Differences Between final, const, and immutable

It’s important to distinguish between final, const (from other languages like C++ or Dart), and immutable. Java’s final keyword is not necessarily about immutability but about preventing reassignment and inheritance. An object reference declared as final can still have an object that internally changes its state – the reference itself just cannot point to a different object.

Comprehensive Use Cases and Best Practices

Using the final keyword efficiently requires understanding specific scenarios and practices:

  • Security-related classes often declare themselves as final to prevent malicious behaviors via subclassing.
  • In high-concurrency scenarios, final variables provide a guaranteed thread-safe shareable state without requiring synchronization.
  • Use final methods when providing critical functionality that should not be altered by any inheriting classes.


Understanding and using the final keyword appropriately in Java is essential for creating robust, secure, and maintainable code. It serves multiple purposes, from creating constants and immutable classes to making methods secure from overrides. Depending on the context, it provides significant advantages:

  • For high-security applications, using final classes can help prevent malicious subclassing.
  • In systems designed for high concurrency, final variables ensure thread safety without the overhead of synchronization.
  • For API developers, final methods can guarantee that the core functionality of your interface remains intact and unaltered.


What is the primary purpose of the ‘final’ keyword in Java?

The final keyword in Java is used to restrict the user from altering values of variables, methods, and classes – meaning variables become constants, methods cannot be overridden, and classes cannot be subclassed.

Can final classes in Java have subclasses?

No, classes declared as final in Java cannot be subclassed. This is to ensure the integrity and security of the application by avoiding alterations through inheritance.

Is a final variable the same as a constant?


In Java, a final variable acts similar to a constant because it cannot be re-assigned once initialized. However, if it is an object, the object’s internal state can still be changed, making it not fully immutable like constants in some other languages.

How does the final keyword enhance security?


The final keyword enhances security by preventing unintended or malicious changes to code logic through variable reassignments, overriding methods or subclassing essential classes, which could compromise the system’s stability and integrity.

Can a final method in Java be overloaded?


Yes, a final method can be overloaded in the same class. Overloading means creating another method with the same name but different parameters. Overloading concerns the method’s inputs, not its behavior or inheritance characteristics.


Feel free to correct, comment, ask further questions or share your experiences with the Java final keyword in the comments below. Your insights could greatly help other readers expand their understanding and practical knowledge of using final in Java programming.

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