How to access Activity from a React Native Android module?

Question

I'm attempting to bridge over the Android functionality of keeping the screen on to React Native. I figured I could do this with a simple module, however I don't know how to get access to the current Android Activity from said module.

I need the Activity reference so I can call .getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); on it

I tried to get the activity via casting like so ((Activity)getReactApplicationContext().getBaseContext()), but this throws a "cannot be cast to Android.app.Activity" error

Answer 1

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(); 

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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