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Gradle Essentials
Gradle Essentials

Gradle Essentials: Master the fundamentals of Gradle using real-world projects with this quick and easy-to-read guide

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Profile Icon Dabir Profile Icon Maheshwari
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€18.99 per month
Full star icon Full star icon Full star icon Half star icon Empty star icon 3.9 (10 Ratings)
Paperback Dec 2015 176 pages 1st Edition
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Arrow left icon
Profile Icon Dabir Profile Icon Maheshwari
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Full star icon Full star icon Full star icon Half star icon Empty star icon 3.9 (10 Ratings)
Paperback Dec 2015 176 pages 1st Edition
eBook
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Gradle Essentials

Chapter 2. Building Java Projects

In the previous chapter, we saw a very basic build script, which just printed the customary Hello World on the console. Now that we are comfortable with the Gradle command line interface, it's a perfect time for us to jump-start our journey with a simple Java project.

In this chapter, we will see how to build and test simple Java projects with Gradle, how external dependencies are added to the classpath, and how building distributable binaries work.

We will try to keep the Java code as minimal as possible so that we can focus more on the build of the project. Along the way, we will learn some best practices that a Gradle-based project should follow. It's okay if we are not able to comprehend all the build script syntax in this chapter because we are going to see that in detail in Chapter 4, Demystifying Build Scripts.

Building a simple Java project

To demonstrate the Java project's build with Gradle, let's create a very simple Java application that will greet a user. Just a tad bit more than a hello world in terms of application logic.

Firstly, create a directory called hello-java. This is our project directory. For the following steps, feel free to choose an IDE/text editor of your choice for editing the files.

Creating a build file

In the root of the project directory, let's create the build.gradle file and add the following code line to it:

apply plugin: 'java'

Yes, that's all that goes into the build file for now, a single line. We will soon see what it means.

Adding source files

By default, like Maven, the Java source files are read from the src/main/java directory of the project. We can configure this, of course, but let's save that for later. Let's create this directory structure in our project.

Now, we need to create a Java class that would generate the greeting...

Unit testing

Unit testing is an indispensable aspect of software development. Testing gives us confidence that our code works fine and provides us a safety net when refactoring. Fortunately, Gradle's Java plugin makes it simple and easy to unit test your code.

We will write a simple test for the same example app we created above. We will create our first unit test now using JUnit (v4.12) library.

Note

More information about JUnit can be found at http://junit.org.

Adding a unit test source

Again, like Maven, Java test sources are kept in the src/test/java directory relative to the project root. We will create this directory and, as a good practice, the test package structure will reflect the same hierarchy as the source packages.

...
src
└── test
    └── java        // test source root
        └── com
            └── packtpub
                └── ge
                    └─...

Bundling an application distributable

In the first example, we ran our application by using the java command directly from the command line. Usually, such command-line applications are shipped with scripts to run the application so that the end user need not always write the whole command by hand. Also, while developing, we repeatedly need to run the app. It would be nicer if we could write a task in our build file such that an app can be run in one Gradle invocation.

The good news is that there already exists such a plugin called application, shipped with Gradle, which can do both for us. For this example, we will copy over the hello-test project as hello-app. Let's make simple modifications to our build.gradle as follows:

apply plugin: 'java'
apply plugin: 'application'

mainClassName = "com.packtpub.ge.hello.Main"
run.args = ["Reader"]

repositories {
    mavenCentral()
}

dependencies {
    testCompile 'junit:junit:4.11'
}

The second...

Generating IDE project files

IDEs are an integral part of a Java developer's tool chain and workflow. However, manually setting up an IDE to correctly identify the project structure and dependencies for any moderately sized project is not an easy task.

Checking-in IDE-specific files or directories such as .classpath, .project, .ipr, .iws, .nbproject, .idea, .settings, .iml, is not a good idea. We know that some still do it because it's hard to generate the IDE file manually every time someone checks the project out of the version control system. However, checking in such files creates problems as they eventually go out of sync from the main build file. Also, this forces the whole team to use the same IDE and manually update the IDE files whenever there is a change in the build.

How nice would it be if we could just check-in only those files that are necessary for a project to be built independent of IDE and let our build system generate a file specific to our favorite IDE? Our wish...

Summary

We started off this chapter by building a very simple Java project. We saw how the intelligent conventions of the java plugin helped us keep the build file concise. Then, we added unit tests to this project and included the JUnit library from the Maven central repository. We made the tests fail and checked the reports to see the explanation. Then, we saw how the application's distribution can be created using the application plugin. Finally, we saw the idea and eclipse plugins that help us generate the IDE-specific files for our project.

Overall, we realized how powerful the plugin system in Gradle is. Gradle, out-of-the-box, ships with many interesting plugins, but we are not forced to use any of them. We will build a web application in the next chapter and also learn how configurations and dependency management works..

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Key benefits

  • Write beautiful build scripts for various types of projects effortlessly
  • Become more productive by harnessing the power and elegance of the Gradle DSL
  • Learn how to use Gradle quickly and effectively with this step-by-step guide

Description

Gradle is an advanced and modern build automation tool. It inherits the best elements of the past generation of build tools, but it also differs and innovates to bring terseness, elegance, simplicity, and the flexibility to build. Right from installing Gradle and writing your first build file to creating a fully-fledged multi-module project build, this book will guide you through its topics in a step-by-step fashion. You will get your hands dirty with a simple Java project built with Gradle and go on to build web applications that are run with Jetty or Tomcat. We take a unique approach towards explaining the DSL using the Gradle API, which makes the DSL more accessible and intuitive. All in all, this book is a concise guide to help you decipher the Gradle build files, covering the essential topics that are most useful in real-world projects. With every chapter, you will learn a new topic and be able to readily implement your build files.

Who is this book for?

This book is for Java and other JVM-based language developers who want to use Gradle or are already using Gradle on their projects. No prior knowledge of Gradle is required, but some familiarity with build-related terminologies and an understanding of the Java language would help.

What you will learn

  • Master the Gradle DSL by identifying the building blocks
  • Learn just enough Groovy for Gradle
  • Set up tests and reports for your projects to make them CI ready
  • Create library, stand-alone, and web projects
  • Craft multi-module projects quickly and efficiently
  • Migrate existing projects to a modern Gradle build
  • Extract common build logic into plugins
  • Write builds for languages like Java, Groovy, and Scala

Product Details

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Publication date, Length, Edition, Language, ISBN-13
Publication date : Dec 23, 2015
Length: 176 pages
Edition : 1st
Language : English
ISBN-13 : 9781783982363
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Product Details

Publication date : Dec 23, 2015
Length: 176 pages
Edition : 1st
Language : English
ISBN-13 : 9781783982363
Tools :

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Table of Contents

10 Chapters
1. Running Your First Gradle Task Chevron down icon Chevron up icon
2. Building Java Projects Chevron down icon Chevron up icon
3. Building a Web Application Chevron down icon Chevron up icon
4. Demystifying Build Scripts Chevron down icon Chevron up icon
5. Multiprojects Build Chevron down icon Chevron up icon
6. The Real-world Project with Gradle Chevron down icon Chevron up icon
7. Testing and Reporting with Gradle Chevron down icon Chevron up icon
8. Organizing Build Logic and Plugins Chevron down icon Chevron up icon
9. Polyglot Projects Chevron down icon Chevron up icon
Index Chevron down icon Chevron up icon

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Js Jun 03, 2018
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Je le recommande:- Intro à Groovy, language de scripting utilisé par Gradle- La philosophie de Gradle, son organisation, etc.- Et comment l'utiliser dans un contexte CI, etc.Ce n'est pas non plus un bouquin exhaustif (que 150 pages), mais juste suffisant pour rentrer dans Gradle.Bref, ravi.
Amazon Verified review Amazon
CCH Apr 04, 2017
Full star icon Full star icon Full star icon Full star icon Full star icon 5
Having first encountered mysterious and incomprehensible (to me) build.gradle files in online collaborations, I finally decided to see what all the fuss was about and bought this book to learn Gradle from scratch. I'm glad I did! In less than 2 hours, I was writing and customizing my own Gradle build scripts. This book is easy to read and full of examples.I highly recommend this book to anyone interested in learning Gradle, especially those who scoff at one-line build.gradle files for their apparent opacity and lack of implementation details (as I once did). This book does not assume that you know Maven (I certainly don't) or any other particular build tool.To get the most out of this book, however, you will need a little bit of Java programming knowledge. If you have ever made a Java program that runs from a .jar file or used a class library stored in a .jar file, then you won't have any trouble.My only other critique of this book would be that I wish it had told me to go look at the official Gradle documentation for the Java plugin right after explaining it, to further demystify the nuts-and-bolts of Gradle.
Amazon Verified review Amazon
Chris F Jul 23, 2018
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The book is true to its title - Gradle "Essentials." I've followed the first three chapters so far and the material enhanced the little knowledge I had about Gradle. If you don't know Gradle and need help scratching the surface, this book is easy to follow. It helped that I knew Maven already, but this book gives you the fundamentals.
Amazon Verified review Amazon
Andre Burgaud Jan 31, 2016
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
Disclosure: I am a technical reviewer for this book.Gradle Essentials is the book I would have liked to read when I started using Gradle. It gives the reader the necessary guidance to get started without prior knowledge of Gradle. There is no complex topics requiring understanding the internals of Gradle. The authors provide practical information that can immediately be applied in the typical stages of software development lifecycle: development, testing, continuous integration and also deployment.In addition to tackling key features of Gradle, the book also contains a couple of great tips that are time savers in Java projects. Among many other features described in the book, I found the two following tips very valuable:Gradle Daemon in Chapter 1: Java is known to be slow to start. When compiling, or running tests, it can be frustrating to have to wait for the build tool to warm up before getting some results. The Gradle daemon addresses this problem.Running a Web Application in Chapter 3: If your project is a classic Java web site that typically results in a war file, you probably have to include documentation to explain how to deploy the war file after having installed a web site container, like Tomcat for example. In chapter 3 the author provides a solution that can reduce all the documentation to:$ git clone your-project$ cd your-project$ gradle runChapter 7 covers testing and surprisingly uses TestNG. I realized that TestNG was still relevant and found it more refreshing then if it had been JUnit. Nevertheless, I was hoping to read about Spock, thinking it would be more inline with the underlying Groovy language common to both Gradle and Spock.I would recommend this book to anyone who is new to Gradle, or someone already using Gradle but who did not have a chance yet to explore further what is really possible with this build tool.
Amazon Verified review Amazon
Jatin Vaidya Jan 01, 2018
Full star icon Full star icon Full star icon Full star icon Empty star icon 4
Succinct like the title suggests. Good read overall and especially for demystifying some of the cryptic syntax used by gradle/groovy.
Amazon Verified review Amazon
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