Preface

With the introduction of Java 8, many functional programming techniques have been added to the language. However, functional programming may seem unfamiliar to developers who are used to using imperative and object-oriented techniques. The new additions to Java 8 offer the opportunity to develop more maintainable and robust applications than that offered by earlier versions of Java.

The goal of this book is to introduce functional programming techniques to developers who are not familiar with this technology. You will be guided through the use of functional programming techniques with the help of numerous examples. Older imperative and object-oriented approaches will be illustrated and contrasted with equivalent functional programming solutions.

What this book covers

Chapter 1, Getting Started with Functional Programming, introduces the essential elements of functional programming as supported by Java 8. This includes the introduction of functional terms complemented by Java 8 examples.

Chapter 2, Putting the Function in Functional Programming, covers the types of functions found in functional programming languages such as high-order functions, first-class functions, and pure functions. The use of lambda expressions in support of functions is explained.

Chapter 3, Function Composition and Fluent Interfaces, addresses how to use functional composition. Also covered are fluent interfaces and the use of default methods.

Chapter 4, Streams and the Evaluation of Expressions, covers the basics of their creation and use. Streams are an important addition to Java.

Chapter 5, Recursion Techniques in Java 8, demonstrates recursion, a very useful functional programming technique. While not new to Java, we explore the topic in depth and examine the use of recursive lambda expressions.

Chapter 6, Optional and Monads, covers the use and the nature of monads in creating fluent interfaces and producing resilient code. The Optional class provides a better way of working with missing data.

Chapter 7, Supporting Design Patterns Using Functional Programming, illustrates design patterns. They play an important role in Java programming. The impact of the functional style of programming and lambda expressions is illustrated.

Chapter 8, Refactoring, Debugging, and Testing, demonstrates how these tools have been affected by the new functional programming techniques and how IDEs support them. These are valuable tools in the development process.

Chapter 9, Bringing It All Together, summarizes many of the functional programming techniques presented earlier that are used in the creation of a demonstration application. Such an application provides a concise illustration of how these techniques support the development of robust and maintainable software.

What you need for this book

Java SDK 1.8 is needed for the functional programming examples encountered in the book. Some of the examples use NetBeans 8.02 and Eclipse IDE for Java developers, Mars Release Version 4.5.0.

Who this book is for

This book is for developers who are already proficient in Java and want to learn how to use the functional programming features of Java 8. Familiarity with basic Java object-oriented programming concepts is all that is needed. You will learn how to apply lambda expressions and other functional programming techniques to create a more elegant and maintainable code.

Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text are shown are follows: "As you may remember, the forEach method accepts a lambda expression which matches the Consumer interface's accept method."

A block of code is shown as follows:

list.forEach(new Consumer<String>() {
    @Override
    public void accept(String t) {
        System.out.println(t);
    }
 });

The output of code sequences is formatted as shown here:

Starting FPS Game
Generating FPS Image
Rendering FPS Image
Updating FPS Game

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "There is the text form as entered by the user such as: drop Axe."

Note

Warnings or important notes appear in a box like this.

Tip

Tips and tricks appear like this.

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