Functional Programming: Functions and Tuples
Learn about features of functions and tuples added in Java 8 for functional programming.
Overview
Java 8 manages to add many features of the functional languages without significantly changing the Java language.
When lambda expressions, method-references, the Stream interface, and immutable data-structures are combined, Java enables a form of functional programming (FP).
For the purposes of this book, the three pillars of FP are as follows:
- Functions
- Immutability
- Concurrency
Functions
Java 8 manages to add many of the features of functional languages without significantly changing the Java language.
The Function interface (and related interfaces IntFunction, DoubleFunction, LongFunction, BiFunction, etc.) represents the compromise made by Java 8 in elevating functions to objects. This interface
allows functions to be passed as arguments, stored as variables, and returned by methods.
The Function interface has the following default methods:
andThen(Function): Returns a composed function that first applies this function to its input, and then applies the given function to the result.compose(Function): Similar toandThenbut in reversed order (first applies the given function to its input, and then this function).identity(): Returns a