Functional programming in Java

Since we have created a lot of code in our example for this chapter, we will look at the functional programming features of Java, which will help us delete many lines from our code. The less code we have, the easier it is to maintain the application; thus, programmers love functional programming. But this is not the only reason why functional programming is so popular. It is also an excellent way to describe certain algorithms in a more readable and less error prone manner than conventional loops.

Functional programming is not a new thing. The mathematical background was developed for it in the 1930s. One of the first (if not the first) functional programming languages is LISP. It was developed in the 1950s and it is still in use, so much that there is a version of the language implemented on the JVM (Clojure).

Functional programming, in short, means that we express the program structure in terms of functions. In this meaning, we should think of functions as...