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Bazel is a popular build tool that is used for developing software projects. It is an open-source build tool that is used by Google to build their own projects. Bazel supports many programming languages, including Java, C++, and Python, and can be used to build software for various platforms, including Android. In this blog, we will discuss how to set up a project with Bazel for building Android applications.
Why Bazel is a Better Build System for Android Development than Gradle:
Bazel and Gradle are both build systems that are widely used for building Android applications. While both tools have their own strengths and weaknesses, there are several reasons why Bazel is considered better than Gradle for Android development.
- Faster build times: One of the primary advantages of using Bazel for Android development is that it provides faster build times compared to Gradle. Bazel uses a distributed caching system that can cache the output of previous builds, reducing the need to rebuild the entire project. This can lead to significant time savings, especially for larger projects.
- Better scalability: Bazel is designed to handle large-scale projects with thousands of source files and dependencies. It can efficiently manage the build process, even for complex projects that involve multiple languages and platforms. In contrast, Gradle can struggle with larger projects, leading to slower build times and increased complexity.
- Improved dependency management: Bazel provides better dependency management than Gradle. Bazel can handle transitive dependencies more efficiently, reducing the need to manually manage dependencies. It can also resolve conflicts between dependencies automatically, ensuring that the correct version of each library is used.
- Reproducible builds: Bazel provides reproducible builds, which means that builds are consistent across different environments and platforms. This can be especially important for large projects that involve multiple teams and build environments. In contrast, Gradle can struggle with reproducibility, which can lead to inconsistencies and errors in the build process.
- Flexibility: Bazel is designed to be highly flexible and extensible, allowing developers to customize the build process to meet their specific needs. It supports multiple programming languages, platforms, and build targets, making it a versatile tool for building complex projects. In contrast, Gradle is primarily designed for building Java projects and can be more difficult to extend for non-Java projects.
Overall, while Gradle is a popular build tool for Android development, Bazel offers several advantages over Gradle in terms of build speed, scalability, dependency management, reproducibility, and flexibility.
Before getting started, make sure you have the following prerequisites:
- A computer running Linux or macOS.
- The latest version of Bazel installed on your machine. You can download it from the official website: https://bazel.build/.
- The latest version of the Android SDK and Android NDK installed on your machine. You can download them from the official website: https://developer.android.com/studio#downloads.
Step 1: Set up a new Android project
First, you need to create a new Android project. You can do this using Android Studio, which is an official IDE for Android development. Open Android Studio and create a new project. Choose the project name, package name, and other settings according to your requirements.
Step 2: Add Bazel support to your Android project
Once you have created a new Android project, you need to add Bazel support to it. To do this, create a new file named “WORKSPACE” in the root directory of your project. This file is used by Bazel to define the project and its dependencies.
Add the following code to the “WORKSPACE” file:
android_sdk_repository( name = "androidsdk", api_level = 28, build_tools_version = "28.0.3", path = "/path/to/android-sdk", ) android_ndk_repository( name = "androidndk", path = "/path/to/android-ndk", api_level = 28, )
Replace “/path/to/android-sdk” and “/path/to/android-ndk” with the actual paths to your Android SDK and Android NDK installations.
Step 3: Create a BUILD file
Next, create a new file named “BUILD” in the root directory of your project. This file is used to define the targets that you want to build with Bazel.
Add the following code to the “BUILD” file:
android_binary( name = "app", srcs = glob(["src/main/java/**/*.java"]), resource_files = glob(["src/main/res/**"]), manifest = "src/main/AndroidManifest.xml", custom_package = "com.example.myapp", multidex = "native", deps = [ "//third_party:androidx", "//third_party:google", "//third_party:okhttp", ], )
This code defines an Android binary target named “app”. The target includes the source files, resources, and manifest file of your Android project. It also specifies the package name of your app and includes the dependencies that you want to build with your project.
Step 4: Add third-party dependencies
If your project uses any third-party libraries or frameworks, you need to add them to your Bazel project. To do this, create a new directory named “third_party” in the root directory of your project.
Next, create a new file named “WORKSPACE” in the “third_party” directory. Add the following code to the “WORKSPACE” file:
maven_jar( name = "androidx", artifact = "androidx.appcompat:appcompat:1.2.0", repository = "https://maven.google.com", ) maven_jar( name = "google", artifact = "com.google.android.material:material:1.2.0", repository = "https://maven.google.com", ) maven_jar( name = "okhttp", artifact = "com.squareup.okhttp3:okhttp:4.9.1", repository = "https://repo1.maven.org/maven2/", )
This code defines the third-party dependencies that your project uses. In this example, we have added three dependencies: androidx.appcompat, com.google.android.material, and com.squareup.okhttp3.
Step 5: Build your Android project with Bazel
Once you have set up your project with Bazel and added the necessary dependencies, you can build your project using the following command:
bazel build //:app
This Command will build the “app” target that you defined in the “BUILD” file. The output APK file will be generated in the “bazel-bin/app.apk” directory.
In this blog, we have discussed how to set up a project with Bazel for building Android applications. Bazel is a powerful build tool that offers many benefits over traditional build tools, including faster build times and better caching. By following the steps outlined in this blog, you can easily set up a new Android project with Bazel and start building high-quality applications.
- Bazel official documentation: https://docs.bazel.build/versions/main/bazel-overview.html
- Bazel for Android Developers: https://bazel.build/versions/6.1.0/start/android-app
- Bazel on GitHub: https://github.com/bazelbuild/bazel
- Bazel blog: https://blog.bazel.build/
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This article was previously published on proandroiddev.com