Can @Value, @Builder, and Required-Arg Constructor Coexist in Lombok?

Discover if it's possible to combine Lombok's `@Value`, `@Builder`, and required-arg constructors effectively in Java.
---
This video is based on the question https://stackoverflow.com/q/74911223/ asked by the user 'Hollis Waite' ( https://stackoverflow.com/u/105863/ ) and on the answer https://stackoverflow.com/a/74911280/ provided by the user 'rzwitserloot' ( https://stackoverflow.com/u/768644/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: With lombok, can required-arg constructor coexist with @Value, @Builder and @Builder.Default annotations?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding the Confusion: Lombok Annotations and Constructors

Java developers often encounter challenges when working with Lombok, a popular library that enhances Java by generating boilerplate code. One common question is whether a required-arg constructor can coexist with Lombok's annotations like @Value, @Builder, and @Builder.Default. This discussion unfolds a practical scenario to clarify this aspect of Lombok.

The Problem Scenario

Using Lombok (version 1.18.24), you may want to create a class where:

A constructor accepts arguments only for non-initialized members.

A builder is also available to facilitate object creation.

Take a look at a simplified example below:

[[See Video to Reveal this Text or Code Snippet]]

However, upon compiling, you receive an error indicating that the constructor cannot be applied due to argument list mismatches. This situation often leads to confusion among developers.

Examining the Solution

The issues at hand primarily stem from the interaction between custom constructors and Lombok-generated code. Here, we'll break down the solution into clear sections to assist you in rectifying your code effectively.

1. Understanding Lombok's Constructor Generation

Lombok automatically generates an all-args constructor unless a custom one is defined. If you create your own constructor, you must explicitly annotate it with @AllArgsConstructor. This generated constructor needs to include default values as well. If you do not handle this properly, you're likely to face compilation errors.

2. The Issue with Custom Constructors

When you define a constructor manually (e.g., Foo(String alpha)), it's critical to ensure that all fields are initialized. In this case, the field bravo is not set, leading to a compilation error that states a required final field might not have been initialized.

3. Correction Using Annotations Properly

To fix your implementation, you can use the following:

[[See Video to Reveal this Text or Code Snippet]]

This code resolves the confusion by defining the required constructor while also ensuring that all members are initialized.

4. Alternative Approach Without Custom Constructor

Another method to consider is entirely removing the custom constructor. Instead, use the builder for instance creation as shown below:

[[See Video to Reveal this Text or Code Snippet]]

This strategy utilizes the builder pattern effectively without introducing unnecessary complications of dual constructor types.

Final Thoughts: The Cost of Hybrid Methods

While it's possible to hybridize your approach with custom constructors and builders, doing so can introduce inefficiencies and lead to confusion among developers. Here are some key takeaways regarding hybridization:

Increased Complexity: Mixing different object creation methods may produce confusing code, making it hard for developers to understand which method to apply in specific scenarios.

Potential Bugs: Having different ways to initialize an object can result in bugs and edge cases that may not be immediately obvious.

Style Consistency: Strive for consistency in your code style to facilitate readability and maintainability.

Adopting a clear and unified approach to object creation can help reduce the chance of errors and improve the overall code quality.

In summary, while it is feasible to combine Lombok’s powerful annotations with custom constructors, it often results in unnecessary complexity. It's recommended to lean more towards the native capabilities of Lombok to simplify your codebase.

Видео Can @Value, @Builder, and Required-Arg Constructor Coexist in Lombok? канала vlogize