ABSTRACT
Functional programming is a method of designing computer programs in which calculations are seen as evaluating mathematical functions. Of fact, functional programming isn't the only programming style used in the real world. Programming techniques are broadly classified into imperative and declarative programming paradigms. Encapsulation is an introductory programming approach in Java, which is an object-oriented language. It promotes concealing an object's internal state and exposing just the methods required to access and alters it. Immutability is a fundamental notion of functional programming that refers to the fact that an entity cannot be changed after its creation. Many functional programming notions are derived from Category Theory, a broad theory of functions in mathematics. It introduces various category ideas, such as functors and natural transformations. The Lambda expression is used to offer an interface implementation that has a functional interface. It aids in iterating, filtering, and extracting data from a collection.
