Learning Java Functional Programming: Create robust and maintainable Java applications using the functional style of programming

Richard M Reese

Richard M. Reese

€45.99

3 (1 Ratings)

Paperback Oct 2015 296 pages 1st Edition

Richard M Reese

Richard M. Reese

€45.99

3 (1 Ratings)

Paperback Oct 2015 296 pages 1st Edition

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Learning Java Functional Programming

Chapter 2. Putting the Function in Functional Programming

In the first chapter, the basic concept of functions and how they are supported by lambda expressions in Java 8 were introduced. In this chapter, we will cover lambda expressions in more depth. We will explain how they satisfy the mathematical definition of a function and how we can use them in supporting Java applications.

In this chapter, you will cover several topics, including:

Lambda expression syntax and type inference
High-order, pure, and first-class functions
Referential transparency
Closure and currying
Common functional interfaces

Our discussions cover high-order functions, first-class functions, and pure functions. Also examined are the concepts of referential transparency, closure, and currying. Examples of nonfunctional approaches are followed by their functional equivalent where practical.

While we used lambda expression extensively in our examples, in the last part of this chapter, a little time will be spent examining...

Lambda expressions revisited

In this section, we will explore the syntax of lambda expression in more depth. So far, we used them without formally describing them. We will also examine other forms they can take.

As mentioned earlier, a lambda expression is essentially an anonymous function. They can be passed to another function or method, returned from a function or a method, and assigned to variables.

A lambda expression consists of an optional parameter list, followed by the lambda operator, and then a body. The lambda operator is a dash followed by the greater than symbol. The body of a lambda expression may be one or more statements and may optionally return a value.

Let's examine several variations of a simple lambda expression. A single value is passed to the function. This value is incremented and then returned. Several equivalent variations of this function are illustrated in the following table:

Variation	Comment
`x -> x + 1`	The simplest form of the function
`(x) -&gt...`

Key benefits

• Explore how you can blend object-oriented and functional programming styles in Java
• Use lambda expressions to write flexible and succinct code
• A tutorial that strengthens your fundamentals in functional programming techniques to enhance your applications

Description

Functional programming is an increasingly popular technology that allows you to simplify many tasks that are often cumbersome and awkward using an object-oriented approach. It is important to understand this approach and know how and when to apply it. Functional programming requires a different mindset, but once mastered it can be very rewarding. This book simplifies the learning process as a problem is described followed by its implementation using an object-oriented approach and then a solution is provided using appropriate functional programming techniques. Writing succinct and maintainable code is facilitated by many functional programming techniques including lambda expressions and streams. In this book, you will see numerous examples of how these techniques can be applied starting with an introduction to lambda expressions. Next, you will see how they can replace older approaches and be combined to achieve surprisingly elegant solutions to problems. This is followed by the investigation of related concepts such as the Optional class and monads, which offer an additional approach to handle problems. Design patterns have been instrumental in solving common problems. You will learn how these are enhanced with functional techniques. To transition from an object-oriented approach to a functional one, it is useful to have IDE support. IDE tools to refactor, debug, and test functional programs are demonstrated through the chapters. The end of the book brings together many of these functional programming techniques to create a more comprehensive application. You will find this book a very useful resource to learn and apply functional programming techniques in Java.

Who is this book for?

If you are a Java developer with object-oriented experience and want to use a functional programming approach in your applications, then this book is for you. All you need to get started is familiarity with basic Java object-oriented programming concepts.

What you will learn

• Use lambda expressions to simplyfy code
• Use function composition to achieve code fluency
• Apply streams to simply implementations and achieve parallelism
• Incorporate recursion to support an application's functionality
• Provide more robust implementations using Optionals
• Implement design patterns with less code
• Refactor object-oriented code to create a functional solution
• Use debugging and testing techniques specific to functional programs

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Frequently bought together

€45.99

Mastering Concurrency Programming with Java 8

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Learning Reactive Programming With Java 8

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Waldorf Jan 09, 2016

I've been reading the Safari Online version of this book and it contains a lot of useful information. I would have given the book 4 stars but for the fact that the book has many, many typos, which is not good for a technical book. There are minor mistakes like misspellings and not matching the plurality of subjects and verbs, but there are also more important mistakes, such as errors in the code examples in the book and in the specifications of classes and interfaces. For example, in Chapter 2, where functional interfaces are discussed, the book says that the functional method in the BinaryOperator<T> interface has return type R, when it should have said T. Similarly, the book says that the getAsInt( ) method in the IntSupplier interface has return type R, when it should have said int. This book was not sufficiently proofread before publication.

Amazon Verified review

Learning Java Functional Programming: Create robust and maintainable Java applications using the functional style of programming

What do you get with Print?

Learning Java Functional Programming

Chapter 2. Putting the Function in Functional Programming

Lambda expressions usage

Functional programming concepts in Java

High-order functions

Lambda expressions revisited

Functional interfaces revisited

Creating a functional interface

Summary

Page 1 of 6

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Learning Java Functional Programming: Create robust and maintainable Java applications using the functional style of programming

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