Chapter 12. Object-Oriented, Functional Programming, and Lambda Expressions

In this chapter, we will discuss functional programming and how Java 9 implements many functional programming concepts. We will work with many examples on how to mix functional programming with object-oriented programming. We will:

• Understand functions and methods as first-class citizens
• Work with functional interfaces and lambda expressions
• Create a functional version of array filtering
• Create a data repository with generics and interfaces
• Filter collections with complex conditions
• Use a map operation to transform values
• Combine a map operation with reduce
• Chain many operations with map and reduce
• Work with different collectors