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Lombok val vs var



Lombok has gained immense popularity among Java developers for its ability to simplify coding practices by reducing boilerplate code. In the vast ocean of features offered by Lombok, two features stand out: val and var. In this deep dive, we’ll uncover the secrets of these two variables and demonstrate their utility.

Embracing Simplicity with Lombok

Before diving into the specifics of val and var, it’s crucial to appreciate Lombok’s overarching goal. Lombok endeavors to make Java code more concise, readable, and less error-prone. By introducing annotations and inbuilt functions, Lombok eradicates the need for repetitive code, letting us focus on the core logic.

Deciphering val and var in Lombok

Lombok val: The Immutable Helper

Lombok introduced val in its 0.10 version. Whenever we use val, Lombok assumes the variable to be final and derives its type based on the initialization value. This means, once initialized, you cannot modify its value, ensuring immutability.

Here’s a basic example:

import lombok.val;

public Class greet() {
 val greeting = "Hello";
 return greeting.getClass();

Lombok translates this to:

final String greeting = "Hello";

Lombok var: The Flexible Companion

The var variable was introduced in Lombok version 1.16.20. Similar to val, it deduces the type based on the initial value. However, unlike val, var is not immutable, allowing further assignments as long as they adhere to the initially inferred type.


import lombok.var;

var subject = "Java";
subject = "Lombok";

This capability is reminiscent of Java 10’s type inference for local variables.

Hands-on with val and var

1. Declaring Simple Types

By employing val, we can quickly declare simple data types such as Strings or Integers:

val country = "USA";
val population = Integer.valueOf(331002651);

Lombok intelligently discerns the type:

final String country = "USA";
final Integer population = Integer.valueOf(331002651);

2. Working with Collections

Using Lombok, declaring collections like Lists and Maps becomes a breeze:

val capitals = new ArrayList<String>();
capitals.add("Washington D.C.");

Lombok discerns the List and its content type:

final List<String> capitals = new ArrayList<String>();

3. Delving into Compound Types

There may be instances where the type inference depends on conditions. In such cases, Lombok determines the most common superclass.

val collectionType = isQueue ? new LinkedList<String>() : new ArrayList<String>();

For the code above, Lombok would infer List as the type since both LinkedList and ArrayList are implementations of the List interface.

In Conclusion

Lombok’s val and var are powerful tools in a developer’s toolkit. They promote clean, concise code, fostering enhanced readability and maintainability. While val ensures immutability, var offers flexibility, both aiding in writing robust Java applications.

As with any tool, the key lies in understanding its nuances and applying it judiciously. With this comprehensive guide, we hope the developer is well-equipped to leverage the might of Lombok in their Java projects.

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