Final Keyword in Java: All You Need to Know

The final keyword in Java is a non-access modifier, which restricts the user and defines entities that cannot be changed or modified. It plays a prominent role when you want a variable to always store the same value. The final keyword in Java is used to enforce constancy or immutability and specifies that the value of the variable or element should not be modified or extended further. This final keyword in Java ensures thread safety, security, error prevention, code optimization, design intent, etc.

In Java, the final keyword can be used relatively in 3 contexts, which are as mentioned:

  1. Final Variable
  2. Final Method
  3. Final Class

Java Final Variable

In Java, a final variable is a variable that can be assigned a value once and cannot further be altered or modified once assigned. This signifies that if we try to alter the value of a Java variable, it will surely display a compilation error on the computer screen. It assigns a variable as a constant and prevents value change. The Java final variable is generally used for mathematical constants like pi, circumference of a circle, volume, etc. and in configuration settings.

Here is an example of declaring and initializing a final variable

Final Int value=5;

Attempting to change the value will later show a complication or syntax error in the code.

Hence, it becomes essential to use the final for those constants and variables whose values should not change during the program's execution.

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Java Final Method

In Java, the final method cannot be overridden by its following subclasses. Therefore, it becomes essential to ensure that the method implemented remains constant for all the subclasses and shouldn't be altered in any scenario. It enhances the possibility of optimizing performance in the program as overridden by subclasses cannot occur.

The other aspects, like the security and functionality of the classes, are even assured when the implemented method is final.

Some common contexts of the use of final keyword in Java are as mentioned :

  • Immutability of the method
  • Used as security-critical method
  • Optimization of performance
  • To define algorithm structure
  • Prevent accidental overrides

Java Final Class

The final class in Java is a class that cannot be further extended or subclassed. If in case once a user declares a class to be final, then the respective class cannot be inherited by the other class.  

Java final classes are used in several instances. Some of the common ones are :

  • Framework and library design
  • Inheritance restrictions
  • Insurance of Security and Stability
  • Helps in designing API (application program interface)
  • Thread safety
  • Creation of immutable objects
  • For Legacy code preservation

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Characteristics Of Final Keyword In Java

As discussed earlier, the final keyword in Java undoubtedly plays a prominent role in indicating an entity (which could be a variable or a class). Or a method has certain constraints. Some of the key characteristics of the final keyword in Java are as follows:


When the final keyword is applied to a variable, class or method, it indicates that the values cannot be altered or extended further once assigned as the final

Method overriding restrictions

As discussed earlier, the final keyword in the Java method prevents overridden subclasses, which improves the security standards and enhances the program execution.

Thread safety

The final keyword in Java prevents multi-threading during program execution, creating code clarity and enabling a developer to be precise and clear with the code base. 

Application program interface (API)

In Java, the final keyword is prominent in developing and preventing overridden public interfaces. This even helps in maintaining consistency and stability in the framework and library.

Code clarity

Using the final keyword in Java clarifies the code base; it makes the code easier to understand for developers and enhances performance in program execution.

Advantage Of Final Variable In Java

The final variable in Java has a number of advantages when it comes to executing programs, better immutability of variables, or prefixing the values of those variables. Some of the most prominent features or advantages of the final variable in Java are as follows.

1. Error prevention

We must consider the prominent role played by the final variable in Java. In that case, we can get an overview by looking at the aspect of error prevention, as assigning the fixed values for the variables enhances the readability ability of a developer and gets code clarity.

2. Debugging and maintenance

It is one of the significant features of the final variable in Java. It reduces the potential for confusion regarding variable values and ensures proper code maintenance.

3. Compiler optimization

The use of final variables can enable certain compiler optimizations.

4. Optimization of performance

The optimization of performance is even an essential feature, as it enhances the execution of the program and optimizes the code runtime.

Disadvantages Of Final Variable In Java

Despite owning this many advantages, the final variable in Java has many disadvantages.

  • Limited Flexibility
  • Initialization Requirement
  • Difficulty In Testing
  • Difficulty In Debugging
  • Less Dynamic

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In conclusion, the final keyword in Java is a powerful tool with advantages and disadvantages, ranging from immutability, defining algorithm structure, providing code clarity, ensuring security and stability, thread safety, and legacy code preservation. Similarly, it deals with many disadvantages, too, like a user or a developer generally needing help in testing and debugging, less dynamic, and limited flexibility, which further complicates the execution of the program. 

It plays a vital role in merits and demerits. In Java, this final keyword even has memory implications depending on where it's being applied, which could be a method, a class or a variable. Nevertheless if we look into the positive side rather than the drawback that it showcases we can possibly see that java final keyword has become prominent in order to restrict the inheritance or keep the value constant and prevent alteration and modifications.

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