Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Free Learning
Arrow right icon
Learning Reactive Programming With Java 8
Learning Reactive Programming With Java 8

Learning Reactive Programming With Java 8: Learn how to use RxJava and its reactive Observables to build fast, concurrent, and powerful applications through detailed examples

eBook
€20.98 €29.99
Paperback
€36.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Table of content icon View table of contents Preview book icon Preview Book

Learning Reactive Programming With Java 8

Chapter 2. Using the Functional Constructions of Java 8

Functional programming is not a new idea; actually, it's pretty old. For example, Lisp, which is a functional language, is the second oldest of today's commonly-used programming languages.

Functional programs are built using small pieces of reusable pure functions (lambdas). The program logic is composed of small declarative steps and not complex algorithms. That's because functional programs minimize the use of state, which makes imperative programs complex and hard to refactor/support.

With Java 8, the Java world got the lambda expressions and the ability to pass functions to functions. With them, we can code in a more functional style and get rid of a lot of the boilerplate code. The other new thing we got with Java 8 is the streams—something very similar to RxJava's observables but not asynchronous. Combining these streams and the lambdas, we are able to create more functional-like programs.

We...

Lambdas in Java 8

The most important change in Java 8 is the introduction of lambda expressions. They enable faster, clearer coding and make it possible to use functional programming.

Java was created back in the '90s as an object-oriented programming language, with the idea that everything should be an object. At that time, object-oriented programming was the principal paradigm for software development. But, recently, functional programming has become increasingly popular because it is well-suited for concurrent and event-driven programming. This doesn't mean that we should stop writing code using object-oriented languages. Instead, the best strategy is to mix elements of object-oriented and functional programming. Adding lambdas to Java 8 ties in with this idea—Java is an object-oriented language, but now it has lambdas, we are able to code using the functional style too.

Let's look at this new feature in detail.

Introducing the new syntax and semantics

In order to...

Implementing the reactive sum example with lambdas

So this time, our main piece of code will be quite similar to the previous one:

ConnectableObservable<String> input = CreateObservable.from(System.in);

Observable<Double> a = varStream("a", input);
Observable<Double> b = varStream("b", input);

reactiveSum(a, b); // The difference

input.connect();

The only difference is that we are going to take a more functional approach in calculating our sum and not to keep the same state. We won't be implementing the Observer interface; instead, we are going to pass lambdas to subscribe. This solution is much cleaner.

The CreateObservable.from(InputStream) method is a lot like we used previously. We will skip it and look at the Observable<Double> varStream(String, Observable<String>) method, which creates the Observable instances representing the collectors:

public static Observable<Double> varStream(
  final String name, Observable<String...

Pure functions and higher order functions

You don't have to remember most of the terms introduced in this chapter; the important thing is to understand how they help us write simplistic but powerful programs.

RxJava's approach has many functional ideas incorporated, so it is important for us to learn how to think in more functional ways in order to write better reactive applications.

Pure functions

A pure function is a function whose return value is only determined by its input, without observable side effects. If we call it with the same parameters n times, we are going to get the same result every single time. For example:

Predicate<Integer> even = (number) -> number % 2 == 0;
int i = 50;
while((i--) > 0) {
  System.out.println("Is five even? - " + even.test(5));
}

Each time, the even function returns False because it depends only on its input, which is the same each time and is not even.

This property of pure functions is called idempotence. Idempotent functions...

Summary

In this chapter, we've looked at some of the functional programming principles and terms. We've learned how to write programs composed of small pure function actions, chained together using higher order functions.

As functional programming is getting increasingly popular, developers proficient in it will be in high demand in the very near future. That's because it helps us achieve scalability and parallelism with ease. And what is more, if we add the reactive idea to it, it becomes even more appealing.

That's why we are going to dive into the RxJava framework in the next chapters, learning how to use it for our benefit. We'll begin with the Observable instance creation techniques. This will provide us with the skill to create an Observable instance from everything, thus turning almost everything into a functional reactive program.

Left arrow icon Right arrow icon

Description

If you are a Java developer that knows how to write software and would like to learn how to apply your existing skills to reactive programming, this book is for you.

Who is this book for?

If you are a Java developer that knows how to write software and would like to learn how to apply your existing skills to reactive programming, this book is for you.

What you will learn

  • Discover what reactive programming is and how you can benefit from it
  • Get to grips with the new functional features of Java 8 and some functional theory
  • Create RxJava Observable instances from virtually any data source
  • Transform, filter, and accumulate your data using various RxJava operators
  • Combine multiple data sources in one dataset, using custom logic
  • Write concurrent programs with ease, scheduling actions on various workers
  • Learn about unit testing asynchronous RxJava logic
  • Extend RxJava by writing your own operators and factory methods
Estimated delivery fee Deliver to Estonia

Premium delivery 7 - 10 business days

€25.95
(Includes tracking information)

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Jun 24, 2015
Length: 182 pages
Edition : 1st
Language : English
ISBN-13 : 9781785288722
Vendor :
Oracle
Category :
Languages :

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Estimated delivery fee Deliver to Estonia

Premium delivery 7 - 10 business days

€25.95
(Includes tracking information)

Product Details

Publication date : Jun 24, 2015
Length: 182 pages
Edition : 1st
Language : English
ISBN-13 : 9781785288722
Vendor :
Oracle
Category :
Languages :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 128.97
Learning Java Functional Programming
€45.99
Mastering Concurrency Programming with Java 8
€45.99
Learning Reactive Programming With Java 8
€36.99
Total 128.97 Stars icon
Banner background image

Table of Contents

9 Chapters
1. An Introduction to Reactive Programming Chevron down icon Chevron up icon
2. Using the Functional Constructions of Java 8 Chevron down icon Chevron up icon
3. Creating and Connecting Observables, Observers, and Subjects Chevron down icon Chevron up icon
4. Transforming, Filtering, and Accumulating Your Data Chevron down icon Chevron up icon
5. Combinators, Conditionals, and Error Handling Chevron down icon Chevron up icon
6. Using Concurrency and Parallelism with Schedulers Chevron down icon Chevron up icon
7. Testing Your RxJava Application Chevron down icon Chevron up icon
8. Resource Management and Extending RxJava Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

Customer reviews

Rating distribution
Full star icon Full star icon Full star icon Half star icon Empty star icon 3.6
(5 Ratings)
5 star 40%
4 star 20%
3 star 20%
2 star 0%
1 star 20%
T. Nield Jul 31, 2015
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Pretty thorough book on RxJava, and even includes content on custom Operators and Transformers. the chapter on Schedulers was very well-explained and makes it clear how subscribeOn() and observeOn() behave. Although I had to re-read several parts of it, this book has helped me understand RxJava better than any other resource I have come across.I highly recommend downloading the source code to follow along rather than reading the code on paper.
Amazon Verified review Amazon
Amazon Customer Mar 29, 2016
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Good
Amazon Verified review Amazon
Dimitri K Feb 18, 2016
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
It is a nice book, thoughtfully written and with many details. One problem is that some complicated issues are explained too shortly, with few words and unclear diagrams, from which it is hard to understand the point. As if the author was in a hurry. I hope second edition will be improved.
Amazon Verified review Amazon
Marty Jul 28, 2017
Full star icon Full star icon Full star icon Empty star icon Empty star icon 3
READ THIS BEFORE BUYINGThis book is very well written, but it is very much out of date. RxJava 2 is very different from RxJava1 which is what this book is based on. If you import the latest version of RxJava, the very first code sample in this book doesn't even compile. I'm bummed because I spent over $20 on this ebook and I can't even use it. You're better off looking at online docs or wait for this author to write a new book.
Amazon Verified review Amazon
Bram Aug 02, 2016
Full star icon Empty star icon Empty star icon Empty star icon Empty star icon 1
One can only assume that this book was reviewed by hamsters who were taught English as a second language. No native speaker so much as breathed in the direction of this book while it was being edited, and it shows.
Amazon Verified review Amazon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is the delivery time and cost of print book? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela
What is custom duty/charge? Chevron down icon Chevron up icon

Customs duty are charges levied on goods when they cross international borders. It is a tax that is imposed on imported goods. These duties are charged by special authorities and bodies created by local governments and are meant to protect local industries, economies, and businesses.

Do I have to pay customs charges for the print book order? Chevron down icon Chevron up icon

The orders shipped to the countries that are listed under EU27 will not bear custom charges. They are paid by Packt as part of the order.

List of EU27 countries: www.gov.uk/eu-eea:

A custom duty or localized taxes may be applicable on the shipment and would be charged by the recipient country outside of the EU27 which should be paid by the customer and these duties are not included in the shipping charges been charged on the order.

How do I know my custom duty charges? Chevron down icon Chevron up icon

The amount of duty payable varies greatly depending on the imported goods, the country of origin and several other factors like the total invoice amount or dimensions like weight, and other such criteria applicable in your country.

For example:

  • If you live in Mexico, and the declared value of your ordered items is over $ 50, for you to receive a package, you will have to pay additional import tax of 19% which will be $ 9.50 to the courier service.
  • Whereas if you live in Turkey, and the declared value of your ordered items is over € 22, for you to receive a package, you will have to pay additional import tax of 18% which will be € 3.96 to the courier service.
How can I cancel my order? Chevron down icon Chevron up icon

Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact [email protected] with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at [email protected] using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy? Chevron down icon Chevron up icon

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on [email protected] with the order number and issue details as explained below:

  1. If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on [email protected] within one hour of placing the order and we will replace/refund you the item cost.
  2. Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on [email protected] who will be able to resolve this issue for you.
  3. You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
  4. Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
  5. If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
  6. Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on [email protected] within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged? Chevron down icon Chevron up icon

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use? Chevron down icon Chevron up icon

You can pay with the following card types:

  1. Visa Debit
  2. Visa Credit
  3. MasterCard
  4. PayPal
What is the delivery time and cost of print books? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela