How to access Activity from a React Native Android module?

I guess getCurrentActivity() method of ReactContextBaseJavaModule might be used like the following code which has been copied from React-Native original code;

import android.app.Activity;
import com.facebook.react.bridge.ReactContextBaseJavaModule;

public class AwesomeModule extends ReactContextBaseJavaModule {

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

  @Override
  public String getName() {
    return "AwesomeAndroid";
  }

  private static final String ERROR_NO_ACTIVITY = "E_NO_ACTIVITY";
  private static final String ERROR_NO_ACTIVITY_MESSAGE = "Tried to do the something while not attached to an Activity";

  @ReactMethod
  public void doSomething(successCallback, errorCallback) {

    final Activity activity = getCurrentActivity();

    if (activity == null) {
      errorCallback(ERROR_NO_ACTIVITY, ERROR_NO_ACTIVITY_MESSAGE);
      return;
    }

  }

}

Editted:

The issue is that getReactApplicationContext() returns the context of the Application and not the Activity. You cannot typecast an Application context to an Activity.

This is a simple workaround

Since usually, there is only one activity (Main Activity) in react-native, We can write a static function in MainActivity to return the activity

private static Activity mCurrentActivity = null;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mCurrentActivity = this;
    ...
}
...
public static Activity getActivity(){
    Activity activity = new Activity();
    activity = mCurrentActivity;
    return activity;
}

then call MainActivity.getActivity() from the bridge modules

CustomReactPackage.java:

public class CustomReactPackage implements ReactPackage {

    private Activity mActivity = null;

    public CustomReactPackage(Activity activity) {
        mActivity = activity;
    }

    @Override
    public List<NativeModule> createNativeModules(ReactApplicationContext reactContext) {
        List<NativeModule> modules = new ArrayList<>();
        // Add native modules here
        return modules;
    }

    public List<Class<? extends JavaScriptModule>> createJSModules() {
        return Collections.emptyList();
    }

    public List<ViewManager> createViewManagers(ReactApplicationContext reactContext) {
        List<ViewManager> modules = new ArrayList<>();
        // Add native UI components here
        modules.add(new LSPlayerManager(mActivity));
        return modules;
    }
}

LSPlayerManager is my native UI component. I define a constructor so that I can pass in the activity:

public LSPlayerManager(Activity activity) {
    mActivity = activity;
}

And finally in MainActivity.java where the ReactInstanceManager is defined, we can pass the activity to our custom React package:

mReactInstanceManager = ReactInstanceManager.builder()
        .setApplication(getApplication())
        .setBundleAssetName("index.android.bundle")
        .setJSMainModuleName("src/index.android")
        .addPackage(new MainReactPackage())
        .addPackage(new CustomReactPackage(this)) // <--- LIKE THIS!
        .setUseDeveloperSupport(BuildConfig.DEBUG)
        .setInitialLifecycleState(LifecycleState.RESUMED)
        .build();

---

UPDATE FOR REACT NATIVE 0.29.0

This is no longer how you access activity in a native module. See https://github.com/facebook/react-native/releases/tag/v0.29.0 for migration instructions