...

include ':VoiceModule', ':app'

project(':VoiceModule').projectDir = new File(rootProject.projectDir, '../node_modules/react-native-android-voice')

...

dependencies {

  ...

  compile project(':VoiceModule')

}

import com.wmjmc.reactspeech.VoicePackage;  // <--- import

public class MainApplication extends Application implements ReactApplication {

...

  @Override

  protected List<ReactPackage> getPackages() {

    return Arrays.<ReactPackage>asList(

      new MainReactPackage(),

      new VoicePackage() // <--- added here

    );

  }

}

import Tts from 'react-native-tts';

Tts.getInitStatus().then(() => {

  Tts.speak('Hello, world!');

});