Integrate a Flutter module into your Android project

To integrate a Flutter module with an existing Android app manually, without using Flutter's Android Studio plugin, follow these steps:

Let's assume that you have an existing Android app at some/path/MyApp, and that you want your Flutter project as a sibling:

cd some/path/
flutter create -t module --org com.example flutter_module

This creates a some/path/flutter_module/ Flutter module project with some Dart code to get you started and an .android/ hidden subfolder. The .android folder contains an Android project that can both help you run a barebones standalone version of your Flutter module via flutter run and it's also a wrapper that helps bootstrap the Flutter module an embeddable Android library.

Flutter requires your project to declare compatibility with Java 11 or later.

Before attempting to connect your Flutter module project to your host Android app, ensure that your host Android app declares the following source compatibility within your app's build.gradle file, under the android { } block.

android {
    // ...
    compileOptions {
        sourceCompatibility = 11 // The minimum value
        targetCompatibility = 11 // The minimum value
    }
}

Starting with Gradle 7, Android recommends using centralized repository declarations in settings.gradle instead of project or module level declarations in build.gradle files.

Before attempting to connect your Flutter module project to your host Android app, make the following changes.

1. Remove the repositories block in all of your app's build.gradle files.

   groovy

   // Remove the following block, starting on the next line
       repositories {
           google()
           mavenCentral()
       }
   // ...to the previous line

2. Add the dependencyResolutionManagement displayed in this step to the settings.gradle file.

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.PREFER_SETTINGS)
    val storageUrl: String = System.getenv("FLUTTER_STORAGE_BASE_URL") ?: "https://storage.googleapis.com"
    repositories {
        google()
        mavenCentral()
        maven("$storageUrl/download.flutter.io")
    }
}

dependencyResolutionManagement {
    repositoriesMode = RepositoriesMode.PREFER_SETTINGS
    String storageUrl = System.env.FLUTTER_STORAGE_BASE_URL ?: "https://storage.googleapis.com"
    repositories {
        google()
        mavenCentral()
        maven {
            url = uri("$storageUrl/download.flutter.io")
        }
    }
}

This option enables a one-step build for both your Android project and Flutter project. This option is convenient when you work on both parts simultaneously and rapidly iterate, but your team must install the Flutter SDK to build the host app.

Include the Flutter module as a subproject in the host app's settings.gradle. This example assumes flutter_module and MyApp exist in the same directory

If you are using Kotlin, apply the following changes:

// Include the host app project. Assumed existing content.
include(":app")            
// Replace "flutter_module" with whatever package_name you supplied when you ran:
// `$ flutter create -t module [package_name]
val filePath = settingsDir.parentFile.toString() + "/flutter_module/.android/include_flutter.groovy"
apply(from = File(filePath))

If you are using Groovy, apply the following changes:

// Include the host app project.
include(":app")                                   // assumed existing content
setBinding(new Binding([gradle: this]))           // new
def filePath = settingsDir.parentFile.toString() + "/flutter_module/.android/include_flutter.groovy" // new
apply from: filePath                              // new

The binding and script evaluation allows the Flutter module to include itself (as :flutter) and any Flutter plugins used by the module (such as :package_info and :video_player) in the evaluation context of your settings.gradle.

Introduce an implementation dependency on the Flutter module from your app:

dependencies {
    implementation(project(":flutter"))
}