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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
Refactor Java code safely — and automatically — with OpenRewrite.
Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.
Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.
Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.
Yes, we're now running our Black Friday Sale. All Access and Pro are 33% off until 2nd December, 2025:
1. Introduction
One of the most interesting features introduced in Java 8 is effectively final. It allows us to not write the final modifier for variables, fields, and parameters that are effectively treated and used like final ones.
In this tutorial, we’ll explore this feature’s origin and how it’s treated by the compiler compared to the final keyword. Furthermore, we’ll explore a solution to use regarding a problematic use-case of effectively final variables.
2. Effectively Final Origin
In simple terms, objects or primitive values are effectively final if we do not change their values after initialization. In the case of objects, if we do not change the reference of an object, then it is effectively final — even if a change occurs in the state of the referenced object.
Prior to its introduction, we could not use a non-final local variable in an anonymous class. We still cannot use variables that have more than one value assigned to them inside anonymous classes, inner classes, and lambda expressions. The introduction of this feature allows us to not have to use the final modifier on variables that are effectively final, saving us a few keystrokes.
Anonymous classes are inner classes and they cannot access non-final or non-effectively-final variables or mutate them in their enclosing scopes as specified by JLS 8.1.3. The same limitation applies to lambda expressions, as having access can potentially produce concurrency issues.
3. Final vs Effectively Final
The simplest way to understand whether a final variable is effectively final is to think whether removing the final keyword would allow the code to compile and run:
@FunctionalInterface
public interface FunctionalInterface {
void testEffectivelyFinal();
default void test() {
int effectivelyFinalInt = 10;
FunctionalInterface functionalInterface
= () -> System.out.println("Value of effectively variable is : " + effectivelyFinalInt);
}
}
Reassigning a value or mutating the above effectively final variable would make the code invalid regardless of where it occurs.
3.1. Compiler Treatment
JLS 4.12.4 states that if we remove the final modifier from a parameter or a local variable in a valid program without introducing compile-time errors, then it becomes effectively final. Moreover, it’s also safe to add the final modifier to an effectively final variable or parameter.
The Java compiler doesn’t do additional optimization for effectively final variables, unlike it does for final variables.
Let’s consider a simple example that declares two final String variables but only uses them for concatenation:
public static void main(String[] args) {
final String hello = "hello";
final String world = "world";
String test = hello + " " + world;
System.out.println(test);
}
The compiler would change the code executed in the main method above to:
public static void main(String[] var0) {
String var1 = "hello world";
System.out.println(var1);
}On the other hand, if we remove the final modifiers, the variables would be considered effectively final, but the compiler won’t remove them since they’re only used for concatenation.
4. Atomic Modification
Generally, it’s not a good practice to modify variables used in lambda expressions and anonymous classes. We cannot know how these variables are going to be used inside method blocks. Mutating them might lead to unexpected results in multithreading environments.
We already have a tutorial explaining the best practices when using lambda expressions and another that explains common anti-patterns when we modify them. But there’s an alternative approach that allows us to modify variables in such cases that achieves thread-safety through atomicity.
The package java.util.concurrent.atomic offers classes such as AtomicReference and AtomicInteger. We can use them to atomically modify variables inside lambda expressions:
public static void main(String[] args) {
AtomicInteger effectivelyFinalInt = new AtomicInteger(10);
FunctionalInterface functionalInterface = effectivelyFinalInt::incrementAndGet;
}5. Conclusion
In this tutorial, we learned about the most notable differences between final and effectively final variables. In addition, we provided a safe alternative that allows us to modify variables inside lambda functions.
