All Android developers are familiar with Gradle. It is a build tool commonly used in application development, one of which is Android.
You can read at https://www.gradle.org/ for more details. Gradle scripts are usually written in the Groovy programming language. Then can Gradle scripts be written with Kotlin? You can. Please read this blog: Kotlin Meets Gradle.
Of course, writing scripts in the programming language we like would be more fun. Besides being easier, we can also better understand what we write.
That’s how I felt when I first tried Kotlin DSL. Especially with some of the “magic” offered by Android Studio, such as auto complete, error detection, and others.
What is Kotlin DSL?
Before that, let’s take a look at what is meant by Kotlin DSL. Kotlin is a programming language rich in interesting features that can make code more concise and expressive.
One of them is support for writing a domain-specific language or DSL. According to Wikipedia, DSL is a computer language specific to a particular application domain. It differs from a general-purpose language which can be applied in all application domains.
One example of implementing DSL that is commonly known by developers is query commands in SQL. Suppose you pay attention to statements in SQL. In that case, they are almost like sentences in English: expressive and easy to read. Example:
The grammar is the most visible difference between the above and the usual code. Code on a DSL is easier for humans to read and understand, even for people who don’t know to program.
In Kotlin, we can find examples of implementing DSL in several libraries, one of which is Anko. Anko is a library in Kotlin that makes developing Android apps faster and easier. If you are interested in Anko, you can learn about it in the Kotlin Android Developer Expert class.
Learn Gradle Kotlin DSL
After knowing a little about Kotlin DSL, it’s time for us to enter the main topic of this tutorial, which is implementing Kotlin DSL on Gradle scripts in an Android project.
Some of the tools/equipment that we have to prepare first are:
- The latest version of Android Studio
- The latest version of Kotlin
- The latest version of Gradle
Gradle Pusposes and Function
Gradle is a powerful and versatile build automation tool that is widely used in the Java ecosystem and beyond. It is designed to make it easy to build various types of projects, such as Java libraries, Android applications, and more.
Gradle achieves this by providing a set of built-in conventions and functionality through plugins.
One of the key features of Gradle is its use of a domain-specific language (DSL) for configuring build tasks.
This DSL allows developers to define and customize various aspects of the build process, such as compiling code, creating a release build, or generating a test report.
Gradle also has a rich ecosystem of plugins that can be easily added to a project to provide additional functionality.
In addition to the built-in plugins and conventions, Gradle also allows developers to create and publish their own custom plugins.
These custom plugins can encapsulate a developer’s own conventions and build functionality, allowing them to be easily reused across multiple projects.
This allows developers to write custom tasks and logic once and share it across multiple projects, making the development and maintenance process more efficient.
Furthermore, Gradle also allows developers to leverage other build tools like Maven and Ivy, to import dependencies and projects.
How Does Gradle Work?
Android Studio, the official Integrated Development Environment (IDE) for Android development, supports Gradle as its build automation system.
This means that developers can use Gradle to manage the build process for their Android apps within the Android Studio environment.
The Android build system, which is based on Gradle, handles tasks such as compiling the app’s resources and source code, packaging them into an APK, and signing the APK with a digital signature.
The build system allows developers to define custom build configurations, which provide flexibility and control over the build process.
For example, developers can create different build variants for different types of builds, such as debug or release builds, and configure properties and options for each variant.
Additionally, the build system also supports build flavors, which allows developers to create different versions of an app with different features, resources and configurations.
The Android build system also integrates with the Android development ecosystem, such as Android Jetpack, AndroidX libraries and Google Play Services, making it easy for developers to include and manage dependencies in their projects.
By using Gradle as its build automation system, Android Studio provides developers with a powerful and flexible tool for managing the build process for their Android apps.
This allows developers to focus on writing code and creating great apps, while the build system handles the tedious tasks of compiling and packaging the app for distribution.
What is Gradle File in Android
Gradle files, also known as build files, are essential scripts that are used to automate various tasks in an Android project. These files are written in a domain-specific language called Groovy, which is similar to Java.
The Gradle build system uses these files to understand the structure of the project, its dependencies, and the tasks that need to be executed to build the project.
The main Gradle file for an Android project is the build.gradle file, which is located in the root directory of the project.
This file contains the configurations for the project, such as the target SDK version, the version of the Android build tools, and the dependencies for the project.
There are also other Gradle files located in the app module, such as the build.gradle file located in the app directory, which contains the configuration for the app module.
The Gradle build system uses these files to generate APKs from the source files in the project. The APK is the package file format used by Android to distribute and install apps on Android devices.
The build system compiles the source files, packages them into an APK, and signs the APK with a digital signature.
In addition to building the APK, Gradle can also perform other tasks such as running unit tests, generating code coverage reports, and creating a bundle for distribution on the Google Play Store.
Gradle also supports multiple build types, build flavors, and other advanced features that help developers to manage the build process and automate common tasks.