enable-libraries-android.md

../README.md#Guides

Enable the New Architecture for Libraries: Android

Once you have defined the JavaScript specs for your native modules as part of the prerequisites, set up the configuration of the Codegen, and follow the Android/Gradle setup, you are now ready to migrate your library to the new architecture. Here are the steps you can follow to accomplish this.

1. Extend or Implement the Code-generated Native Interfaces

The JavaScript spec for your native module or component will be used to generate native interface code for each supported platform (i.e., Android and iOS). These native interface files will be generated when a React Native application that depends on your library is built.

While this generated native interface code will not ship as part of your library, you do need to make sure your Java/Kotlin code conforms to the protocols provided by these native interface files.

You can invoke the generateCodegenArtifactsFromSchema Gradle task to generate your library’s native interface code in order to use them as a reference:

./gradlew generateCodegenArtifactsFromSchema

The files that are output can be found inside build/generated/source/codegen and should not be committed, but you’ll need to refer to them to determine what changes you need to make to your native modules in order for them to provide an implementation for each generated interface.

The output of the Codegen for a module called NativeAwesomeManager will look like this:

app/build/generated/source/codegen
├── java
│   └── com
│       └── example
│           └── samplelibrary
│               └── NativeAwesomeManagerSpec.java
├── jni
│   ├── Android.mk
│   ├── CMakeLists.txt
│   ├── react
│   │   └── renderer
│   │       └── components
│   │           └── samplelibrary
│   │               ├── ComponentDescriptors.h
│   │               ├── EventEmitters.cpp
│   │               ├── EventEmitters.h
│   │               ├── Props.cpp
│   │               ├── Props.h
│   │               ├── ShadowNodes.cpp
│   │               └── ShadowNodes.h
│   ├── samplelibrary-generated.cpp
│   └── samplelibrary.h
└── schema.json

Extends the Abstract Class Provided by the Codegen

Update your native module or component to ensure it extends the abstract class that has been code-generated from your JavaScript specs (i.e., the NativeAwesomeManagerSpec.java file from the previous example).

Following the example set forth in the previous section, your library might import NativeAwesomeManagerSpec, implement the relevant native interface and the necessary methods for it:

Java

import androidx.annotation.NonNull;

import com.example.samplelibrary.NativeAwesomeManagerSpec;
import com.facebook.react.bridge.Promise;
import com.facebook.react.bridge.ReactApplicationContext;

public class NativeAwesomeManager extends NativeAwesomeManagerSpec {

    public static final String NAME = "NativeAwesomeManager";

    public NativeAwesomeManager(ReactApplicationContext reactContext) {
        super(reactContext);
    }

    @Override
    public void getString(String id, Promise promise) {
        // Implement this method
    }

    @NonNull
    @Override
    public String getName() {
        return NAME;
    }
}

Kotlin

import com.example.samplelibrary.NativeAwesomeManagerSpec
import com.facebook.react.bridge.Promise
import com.facebook.react.bridge.ReactApplicationContext

class NativeAwesomeManager(reactContext: ReactApplicationContext) :
    NativeAwesomeManagerSpec(reactContext) {
    override fun getString(id: String, promise: Promise) {
        // Implement this method
    }

    override fun getName() = NAME

    companion object {
        val NAME = "NativeAwesomeManager"
    }
}

Please note that the generated abstract class that you’re now extending (MyAwesomeSpec in this example) is itself extending ReactContextBaseJavaModule. Therefore you should not lose access to any of the method/fields you were previously using (e.g., the ReactApplicationContext and so on). Moreover, the generated class will now also implement the TurboModule interface for you.

---

Important

This documentation is still experimental and details are subject to changes as we iterate. Feel free to share your feedback on this discussion.

Moreover, it contains several manual steps. Please note that this won't be representative of the final developer experience once the New Architecture is stable. We're working on tools, templates and libraries to help you get started fast on the New Architecture, without having to go through the whole setup.