The biggest FP language in use is JavaScript. The ecosystem is probably bigger than Java’s (more projects on Github) or comparable. There’s almost as many job listings (http://www.codingdojo.com/blog/wp-content/uploads/Programming-Languages-for-2016_graph.jpg) and it’s rising way faster in popularity than Java right now.
COBOL was replaced by Java, Java will be replaced by JavaScript, a language that CAN do FP and has a more advanced form of objects. Prototypal objects are a superset of class-based objects, meaning it’s easy to write class-based OO in JavaScript, it’s hard to write prototypal code in Java (you lose type-soundness or you have to work with very advanced design patterns). Try writing the code from this article in Java and you’ll see.
