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Immutable Data Structures in Java

As part of some of the coding interviews I’ve been conducting recently, the topic of immutability sometimes comes up. I’m not overly dogmatic in it myself, but whenever there’s no need for mutable state, I try to get rid of code which makes code mutable, which is often most visible in data structures. However, there seems to be a bit of a misunderstanding on the concept of immutability, where developers often believe that having a final reference, or val in Kotlin or Scala, is enough to make an object immutable. This blogpost dives a bit deeper in immutable references and immutable data structures.

Benefits of Immutable Data Structures

Immutable data structures have significant benefits, such as:

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Immutable Data With FunctionalJ.io

Immutability is an important principle of functional programming. Mutable objects hide changes. And hidden changes can lead to unpredictability and chaos.

FunctionalJ provides ways to create and manipulate immutable data. In this article, I discuss @Struct, which generates custom immutable classes. On the surface, it is very similar in concept with Lombok's @Value. However, FunctionalJ's @Struct comes with its own unique features, such as: