How To Build A Fat/Uber AAR From Multi-Module Kotlin Multiplatform Library Project

Are you tired of dealing with multiple AARs and confusion when it comes to integrating your Kotlin Multiplatform Library Project with Android? Well, you’re in luck! In this article, we’ll dive into the process of building a Fat/Uber AAR from a Multi-Module Kotlin Multiplatform Library Project. By the end of this tutorial, you’ll be able to create a single, self-contained AAR that simplifies the integration process and makes your life as a developer easier.

What is a Fat/Uber AAR?

Before we dive into the process, let’s quickly explain what a Fat/Uber AAR is. A Fat/Uber AAR is a single Android Archive (AAR) file that contains all the dependencies and modules of your Multi-Module Kotlin Multiplatform Library Project. This means that instead of having multiple AARs for each module, you have one AAR that contains everything. This simplifies the integration process and makes it easier to manage your project.

Prerequisites

Before we begin, make sure you have the following:

• A Kotlin Multiplatform Library Project with multiple modules
• Gradle build system (we’ll be using Gradle 6.x in this tutorial)
• Android Studio (optional but recommended)

Step 1: Create a New Gradle Module for the Fat/Uber AAR

In your Kotlin Multiplatform Library Project, create a new Gradle module. This module will be responsible for building the Fat/Uber AAR. Name it something like `fat-aar` or `uber-aar`. Create a new folder for the module and add a `build.gradle` file with the following contents:

apply plugin: 'com.android.library'

android {
  compileSdkVersion 29
  defaultConfig {
    minSdkVersion 21
    targetSdkVersion 29
    versionCode 1
    versionName "1.0"
  }
  buildTypes {
    release {
      minifyEnabled false
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-project.txt'
    }
  }
}

dependencies {
  implementation project(':module1')
  implementation project(':module2')
  implementation project(':module3')
  // Add dependencies for each module in your project
}

In this example, we’re creating a new Android library module that depends on three other modules (`module1`, `module2`, and `module3`) in our project. You’ll need to add dependencies for each module in your project.

Step 2: Configure the Fat/Uber AAR Module

In the `build.gradle` file, add the following configuration:

android {
  // ...
  libraryVariants.all { variant ->
    variant.outputs.each { output ->
      if (output_OutputType == com.android.build.gradle.internal.api.ApkVariantOutputImpl) {
        def outputFile = output.outputFileName
        if (outputFile != null && outputFile.endsWith('.aar')) {
          def fatAarFile = file("fat-aar-${variant.name}.aar")
          project.copy {
            from file(output.outputFileName)
            into file("${project.buildDir}/outputs/aar")
            rename { StringBuilder	StringBuilderBuilder it ->
              it.insert(0, 'fat-aar-')
            }
          }
        }
      }
    }
  }
}

This configuration tells Gradle to create a new AAR file for each variant (e.g., debug, release) and rename it to include the `fat-aar` prefix.

Step 3: Build the Fat/Uber AAR

Run the following command in your terminal or command prompt:

./gradlew :fat-aar:assemble

This will build the Fat/Uber AAR for each variant in your project. You can find the generated AAR files in the `build/outputs/aar` directory.

Step 4: Integrate the Fat/Uber AAR with Your Android Project

Now that you have the Fat/Uber AAR, it’s time to integrate it with your Android project. Add the following dependency to your Android project’s `build.gradle` file:

dependencies {
  implementation files('path/to/fat-aar.aar')
}

Replace `path/to/fat-aar.aar` with the actual path to the Fat/Uber AAR file you generated earlier.

Common Issues and Troubleshooting

Here are some common issues you might encounter and their solutions:

Issue	Solution
Error: “Failed to resolve: fat-aar.aar”	Make sure the path to the Fat/Uber AAR file is correct and that the file exists.
Error: ” duplicate class: …”	This means that there are duplicate classes in your modules. Make sure to use unique package names for each module.
Fat/Uber AAR is not being generated	Check the Gradle build log for errors. Make sure the `fat-aar` module is configured correctly and that the dependencies are correct.

Conclusion

In this article, we’ve covered the process of building a Fat/Uber AAR from a Multi-Module Kotlin Multiplatform Library Project. By following these steps, you can simplify the integration process and make your life as a developer easier. Remember to troubleshoot common issues and configure your project correctly to avoid any problems.

Happy coding!

Here are 5 Questions and Answers about “How To Build A Fat / Uber AAR From Multi Module Kotlin Multiplatform Library Project”:

Frequently Asked Question

Are you tired of struggling to build a fat/uber AAR from your multi-module Kotlin multiplatform library project? Well, you’re not alone! We’ve got the answers to your most burning questions.