Book Image

Java 9 Programming By Example

By : Peter Verhas
Book Image

Java 9 Programming By Example

By: Peter Verhas

Overview of this book

This book gets you started with essential software development easily and quickly, guiding you through Java’s different facets. By adopting this approach, you can bridge the gap between learning and doing immediately. You will learn the new features of Java 9 quickly and experience a simple and powerful approach to software development. You will be able to use the Java runtime tools, understand the Java environment, and create Java programs. We then cover more simple examples to build your foundation before diving to some complex data structure problems that will solidify your Java 9 skills. With a special focus on modularity and HTTP 2.0, this book will guide you to get employed as a top notch Java developer. By the end of the book, you will have a firm foundation to continue your journey towards becoming a professional Java developer.
Table of Contents (17 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback


Java drastically changed with the introduction of Java 8, and this change has been elevated to a whole new level with the new version, Java 9. Java has a well-established past, being more than 20 years old, but at the same time, it is new, functional, reactive, and sexy. This is a language that developers love, and at the same time, it is the number one choice of developer language for many enterprise projects.

It is probably more lucrative to learn Java now than ever before, starting with Java 9. We encourage you to start your professional developer career by learning Java 9, and we have done our best in this book to help you along this road. We assembled the topics of the book so that it is easy to start, and you can feel the things working and moving very soon. At the same time, we have tried to reach very far, signaling the road ahead for a professional developer.

The sands of time kept moving, and I discovered functional programming.

I could very well see why writing side-effect-free code worked! I was hooked and started playing with Scala, Clojure, and Erlang. Immutability was the norm here.

However, I wondered how traditional algorithms would look in a functional setting and started learning about it.

A data structure is never mutated in place. Instead, a new version of the data structure is created. The strategy of copy and write with maximized sharing was an intriguing one! All that careful synchronization is simply not needed!

The languages come equipped with garbage collection. So, if a version is not needed anymore, runtime would take care of reclaiming the memory.

All in good time, though! Reading this book will help you see that we need not sacrifice algorithmic performance while avoiding in-place mutation!

What this book covers 

Chapter 1, Getting Started with Java 9, gives you a jump start in Java, helping you install it on your computer and run your first interactive programs using the new Jshell.

Chapter 2, The First Real Java Program - Sorting Names, teaches you how to create a development project. This time, we will create program files and compile the code.

Chapter 3, Optimizing the Sort - Making Code Professional, develops the code further so that the code is reusable and not only a toy.

Chapter 4, Mastermind - Creating a Game, is when some fun starts. We develop a game application that is interesting and not as trivial as it first seems, but we will do it.

Chapter 5, Extending the Game - Run Parallel, Run Faster, shows you how to utilize the multi-processor capabilities of modern architecture. This is a very important chapter that details technologies, that only a few developers truly understand.

Chapter 6, Making Our Game Professional - Do it as a Webapp, transforms the user interface from command-line to web browser-based, delivering better user experience.

Chapter 7, Building a Commercial Web Application Using REST, takes you through the development of an application that has the characteristics of many commercial applications. We will use the standard REST protocol which has gained ground in enterprise computing.

Chapter 8, Extending Our E-Commerce Application, helps you develop the application further utilizing modern language features such as scripting and lambda expressions.

Chapter 9, Building an Accounting Application Using Reactive Programming, teaches you how to approach some problems using reactive programming.

Chapter 10, Finalizing Java Knowledge to a Professional Level, gives a bird's-eye view of developer topics that play an important role in the life of a Java developer, and which will guide you further in working as a professional developer.

What you need for this book 

To immerse into the content of this book and to soak up most of the skills and knowledge, we assume that you already have some experience with programming. We do not assume too much but hope that you already know what a variable is, that computers have memory, disk, network interfaces, and what they generally are. In addition to these basic skills, there are some technical requirements to try out the code and the examples of the book. You need a computer—something that is available today and can run Windows, Linux, or OSX. You need an operating system and, probably, that is all you need to pay for. All other tools and services that you will need are available as open source and free of charge. Some of them are also available as commercial products with an extended feature set, but for the scope of this book, starting to learn Java 9 programming, those features are not needed. Java, a development environment, build tools, and all other software components we use are open source.

Who this book is for 

This book is for anyone who wants to learn the Java programming language. You are expected to have some prior programming experience with another language, such as JavaScript or Python, but no knowledge of earlier versions of Java is assumed.


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, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "The following function f has a side effect, though."

A block of code is set as follows:


public interface Sort { 
 void sort(SortableCollection collection); 

If there is a line (or lines) of code that needs to be highlighted, it is set as follows:

title=Book Java 9 by Example
description=a new book to learn Java 9 

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: "Clicking the Next button moves you to the next screen."


Warnings or important notes appear in a box like this.


Tips and tricks appear like this.

Reader feedback

Feedback from our readers is always welcome. Let us know what you think about this book—what you liked or disliked. Reader feedback is important for us as it helps us develop titles that you will really get the most out of.

To send us general feedback, simply e-mail [email protected], and mention the book's title in the subject of your message.

If there is a topic that you have expertise in and you are interested in either writing or contributing to a book, see our author guide at

Customer support

Now that you are the proud owner of a Packt book, we have a number of things to help you to get the most from your purchase.

Downloading the example code

You can download the example code files for this book from your account at If you purchased this book elsewhere, you can visit and register to have the files e-mailed directly to you.

You can download the code files by following these steps:

  1. Log in or register to our website using your e-mail address and password.
  2. Hover the mouse pointer on the SUPPORT tab at the top.
  3. Click on Code Downloads & Errata.
  4. Enter the name of the book in the Search box.
  5. Select the book for which you're looking to download the code files.
  6. Choose from the drop-down menu where you purchased this book from.
  7. Click on Code Download.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

  • WinRAR / 7-Zip for Windows
  • Zipeg / iZip / UnRarX for Mac
  • 7-Zip / PeaZip for Linux

The code bundle for the book is also hosted on GitHub at We also have other code bundles from our rich catalog of books and videos available at Check them out!


Although we have taken every care to ensure the accuracy of our content, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in the text or the code—we would be grateful if you could report this to us. By doing so, you can save other readers from frustration and help us improve subsequent versions of this book. If you find any errata, please report them by visiting, selecting your book, clicking on the Errata Submission Form link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata will be uploaded to our website or added to any list of existing errata under the Errata section of that title.

To view the previously submitted errata, go to and enter the name of the book in the search field. The required information will appear under the Errata section.


Piracy of copyrighted material on the Internet is an ongoing problem across all media. At Packt, we take the protection of our copyright and licenses very seriously. If you come across any illegal copies of our works in any form on the Internet, please provide us with the location address or website name immediately so that we can pursue a remedy.

Please contact us at [email protected] with a link to the suspected pirated material.

We appreciate your help in protecting our authors and our ability to bring you valuable content.


If you have a problem with any aspect of this book, you can contact us at [email protected], and we will do our best to address the problem.