The book will also help you set up unit and integration testing with different libraries and will show how Gradle and Android Studio can make running tests easier. Finally, you will be shown a number of tips and tricks on the advanced customization of your application's build process.
By the end of this book, you will be able to customize the entire build process, and create your own tasks and plugins for your Gradle builds. When Google introduced Gradle and Android Studio, they had some goals in mind. They wanted to make it easier to reuse code, create build variants, and configure and customize the build process. Running Gradle from the command line or on a continuous integration server will always yield the same results as running a build from Android Studio.
We will refer to Android Studio occasionally throughout the book, because it often provides a simpler way of setting up projects, dealing with changes, and so on. Android Studio was announced and released as an early access preview by Google in May , alongside support for Gradle.
Compared to Eclipse, Android Studio has an improved user interface designer, a better memory monitor, a nice editor for string translation, warnings for possible Android-specific issues and a lot more features aimed at Android developers.
This special view groups Gradle scripts, drawables, and other resources in a convenient way. As soon as the stable version 1.
This means that Google will not provide new features for Eclipse anymore, and all IDE-related tool development is now focused on Android Studio. If you are still using Eclipse, it is time to change if you do not want to be left behind. This screenshot shows what Android Studio looks like for a simple Android app project:. There are four different update channels for Android Studio:. The Stable channel, which is the default, features thoroughly tested releases that should be bug-free.
By default, Android Studio checks every time it starts if there any updates available and notifies you. When you launch Android Studio for the first time, it starts a wizard to set up your environment and to make sure you have the latest Android SDK and the necessary Google repositories. In order for an Android project to be built using Gradle, you need to set up a build script.
This will always be called build. You will notice, as we go through the basics, that Gradle favors convention over configuration and generally provides default values for settings and properties. This makes it a lot easier to get started with a lot less configuration than that found in systems such as Ant or Maven, which have been the de facto build systems for Android projects for a long time.
You do not need to absolutely comply with these conventions though, as it is usually possible to override them if needed. The team behind Gradle believes that using a declarative, DSL-style approach based on a dynamic language has significant advantages over using the more procedural, free-floating style of Ant, or any XML-based approach used by many other build systems.
That does not mean you need to know Groovy to get started with your build scripts. It is easy to read, and if you already know Java, the learning curve is not that steep. If you want to start creating your own tasks and plugins which we will talk about in later chapters , it is useful to have a deeper understanding of Groovy.
The two most important concepts in Gradle are projects and tasks. Every build is made up of at least one project, and every project contains one or more tasks. Every build. Tasks are then simply defined inside the build script. When initializing the build process, Gradle assembles Project and Task objects based on the build file.
A Task object consists of a list of Action objects, in the order they need to be executed. An Action object is a block of code that is executed, similar to a method in Java.
Executing a Gradle build is, in its simplest form, just executing actions on tasks, which are dependent on other tasks. To simplify the build process, the build tools create a dynamic model of the workflow as a Directed Acyclic Graph DAG. This means all the tasks are processed one after the other and loops are not possible.
Once a task has been executed, it will not be called again. Tasks without dependencies will always be run before the others. The dependency graph is generated during the configuration phase of a build. A Gradle build has three phases:. Initialization : This is where the Project instance is created.
If there are multiple modules, each with their own build. Configuration : In this phase, the build scripts are executed, creating and configuring all the tasks for every project object.
Execution : This is the phase where Gradle determines which tasks should be executed. Which tasks should be executed depends on the arguments passed for starting the build and what the current directory is. In order to have Gradle build a project, there always needs to be a build. A build file for Android has a few required elements:. This is where the actual build is configured. In the repositories block, the JCenter repository is configured as a source of dependencies for the build script.
JCenter is a preconfigured Maven repository and requires no extra setup; Gradle has you covered. There are several repositories available straight from Gradle and it is easy to add your own, either local or remote.
The build script block also defines a dependency on Android build tools as a classpath Maven artifact. This is where the Android plugin comes from. The Android plugin provides everything needed to build and test applications. Every Android project needs to apply the Android plugin using this line:. Plugins are used to extend the capabilities of a Gradle build script. Applying a plugin to a project makes it possible for the build script to define properties and use tasks that are defined in the plugin.
If you are building a library, you need to apply 'com. You cannot use both in the same module because that would result in a build error. A module can be either an Android application or an Android library, not both. When using the Android plugin, Android-specific conventions can be configured and tasks only applicable to Android will be generated.
The Android block in the following snippet is defined by the plugin and can be configured per project:. This is where the Android-specific part of the build is configured. The only required properties are the compilation target and the build tools. The compilation target, specified by compileSdkVersion , is the SDK version that should be used to compile the app.
It is good practice to use the latest Android API version as the compilation target. There are plenty of customizable properties in the build. We will discuss the most important properties in Chapter 2 , Basic Build Customization , and more possibilities throughout the rest of the book.
Compared to the old Eclipse projects, the folder structure for Android projects has changed considerably. As mentioned earlier, Gradle favors convention over configuration and this also applies to the folder structure. Gradle projects usually have an extra level at the root. This makes it easier to add extra modules at a later point.
All source code for the app goes into the app folder. The folder is also the name of the module by default and does not need to be named app. If you use Android Studio to create a project with both a mobile app and an Android Wear smartwatch app, for example, the modules are called application and wearable by default. Gradle makes use of a concept called source set. The official Gradle documentation explains that a source set is a group of source files, which are compiled and executed together.
For an Android project, main is the source set that contains all the source code and resources for the default version of the app. When you start writing tests for your Android app, you will put the source code for the tests inside a separate source set called androidTest , which only contains tests.
These are external libraries. Creating a new project in Android Studio starts with a wizard that helps set everything up. The first screen is for setting up the application name and the company domain. The application name is the name that will be used as the name of the app when it is installed and is used as the toolbar title by default. Gradle is an open source build automation system that introduces a Groovy-based domain-specific language DSL to configure projects.
Using Gradle makes it easy for Android developers to manage dependencies and set up the entire build process. This book begins by taking you through the basics of Gradle and how it works with Android Studio.
Furthermore, you will learn how to add local and remote dependencies to your project. You will work with build variants, such as debug and release, paid and free, and even combinations of these things.
The book will also help you set up unit and integration testing with different libraries and will show how Gradle and Android Studio can make running tests easier. Finally, you will be shown a number of tips and tricks on the advanced customization of your application's build process.
Learn Android Studio covers Android Studio and its rich tools ecosystem, including Git and Gradle: this book covers how Android Studio works seamlessly with Git, for source control, and Gradle, a build and test tool. With this book, you'll learn the latest and most productive tools in the Android tools ecosystem, and the best practices for Android app development.
Case studies included in this book. Creating a Gradle -based application template manually Gradle is a more versatile Java building tool compared to Ant, It's not the only build. It tells gradle , the Android build system, how to build the various subdirectories in your project. Scripts: Setting. If you've not done so already, launch the Android Studio development environment with the quick launch icon you created in Chapter 2. Fully updated for Android Studio 3. Building the Android project with Gradle We created the application with one simple activity and now we will try to build the application with Gradle.
Android Studio has automatically generated two build files for the project; Unleash the power of the Android OS and build the kinds of brilliant, innovative apps users love to use If you already know your way around the Android OS and can build a simple Android app in under an hour, this book is for you.
In this new edition of Android App Development For Dummies, you'll find easy-to-follow access to the latest programming techniques that take advantage of the new features of the Android operating system. Apache Ant can be downloaded from Figure Some projects may have more than one module and it may be useful to define some Skip to content. Furthermore, you will learn how to add local and remote dependencies to your project. You will work with build variants, such as debug and release, paid and free, and even combinations of these things.
The book will also help you set up unit and integration testing with different libraries and will show how Gradle and Android Studio can make running tests easier. Finally, you will be shown a number of tips and tricks on the advanced customization of your application's build process.
By the end of this book, you will be able to customize the entire build process, and create your own tasks and plugins for your Gradle builds.
Gradle is based on Groovy, yet very little knowledge of the JVM language is required for you to get started. Packed with best practices and advanced tips and techniques on Android tools, development cycle, continuos integration, release management, testing, and performance, this book offers professional guidance to experienced developers who want to push the boundaries of the Android platform with the developer tools. You'll discover how to use the tools and techniques to unleash your true potential as a developer.
Discover the basics of working in Android Studio and Gradle, as well as the application architecture of the latest Android platform Understand Native Development Kit and its integration with Android Studio Complete your development lifecycle with automated tests, dependency management, continuos integration and release management Writing your own Gradle plugins to customize build cycle Writing your own plugins for Android Studio to help your development tasks.
Expert Android Studio is a tool for expert and experienced developers who want to learn how to make use of the tools while creating Android applications for use on mobile devices.
The book gives an overview of the new features and capabilities, you're getting to know the work surface, launch new Android projects, import of projects, covert old Eclipse project, learn about the Gradle build system, Signing apps, Creating and running Test projects, Action Bar Sherlock integration, Ads integration , Creation of local Maven repositories Google cloud Endpoints. I'm sure there are some typos somewhere and I will make an effort to improve the text with every update.
But most important for me was, to make an easy understandable, straight forward introduction into Android Studio. Since Android Studio is still in development, the book will also evolve with the progress of the program and will be updated frequently.
Built on Ant and Maven concepts, Gradle uses a Groovy-based domain-specific language rather than XML for declaring the project configuration. This video helps Groovy and Java programmers quickly master this Android build tool.
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