Introduction

Functional programming is the ability to treat a certain piece of functionality as an object and pass it as a parameter or the return value of a method. This feature is present in many programming languages, and Java acquired it with the release of Java 8.  

It avoids creating a class, its object, and managing the object state. The result of a function depends only on the input data, no matter how many times it is called. This style makes the outcome more predictable, which is the most attractive aspect of functional programming.

Its introduction to Java also allows us to improve parallel programming capabilities in Java by shifting the responsibility of parallelism from the client code to the library. Before this, in order to process elements of Java collections, the client code had to acquire an iterator from the collection and organize the processing of the collection.

 

Some of the default methods of Java collections accept a function (an implementation of a functional interface...