com.facebook.react.ReactNativeHost Java Examples

/**
 * Demonstrates how to add a custom option to the dev menu.
 * https://stackoverflow.com/a/44882371/3968276
 * This only works from the debug build with dev options enabled.
 */
@Override
@CallSuper
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    MainApplication application = (MainApplication) getApplication();
    ReactNativeHost reactNativeHost = application.getReactNativeHost();
    ReactInstanceManager reactInstanceManager = reactNativeHost.getReactInstanceManager();
    DevSupportManager devSupportManager = reactInstanceManager.getDevSupportManager();
    devSupportManager.addCustomDevOption("Custom dev option", new DevOptionHandler() {
        @Override
        public void onOptionSelected() {
            if (NotificationManagerCompat.from(MainActivity.this).areNotificationsEnabled()) {
                Toast.makeText(MainActivity.this, CUSTOM_DEV_OPTION_MESSAGE, Toast.LENGTH_LONG).show();
            } else {
                AlertDialog dialog = new AlertDialog.Builder(MainActivity.this).create();
                dialog.setTitle("Dev option");
                dialog.setMessage(CUSTOM_DEV_OPTION_MESSAGE);
                dialog.show();
            }
        }
    });
}
 

@ReactMethod
void callJavaScript() {
    Activity activity = getCurrentActivity();
    if (activity != null) {
        MainApplication application = (MainApplication) activity.getApplication();
        ReactNativeHost reactNativeHost = application.getReactNativeHost();
        ReactInstanceManager reactInstanceManager = reactNativeHost.getReactInstanceManager();
        ReactContext reactContext = reactInstanceManager.getCurrentReactContext();

        if (reactContext != null) {
            CatalystInstance catalystInstance = reactContext.getCatalystInstance();
            WritableNativeArray params = new WritableNativeArray();
            params.pushString("Hello, JavaScript!");

            // AFAIK, this approach to communicate from Java to JavaScript is officially undocumented.
            // Use at own risk; prefer events.
            // Note: Here we call 'alert', which shows UI. If this is done from an activity that
            // doesn't forward lifecycle events to React Native, it wouldn't work.
            catalystInstance.callFunction("JavaScriptVisibleToJava", "alert", params);
        }
    }
}
 

public RNThreadModule(final ReactApplicationContext reactContext, ReactNativeHost reactNativehost, ReactPackage additionalThreadPackages[]) {
  super(reactContext);
  this.reactApplicationContext = reactContext;
  threads = new HashMap<>();
  this.reactNativeHost = reactNativehost;
  this.additionalThreadPackages = additionalThreadPackages;
  reactContext.addLifecycleEventListener(this);
}
 

@Nullable
public static CatalystInstance getCatalystInstance(ReactNativeHost host) {
    ReactInstanceManager manager = host.getReactInstanceManager();
    if (manager == null) {
        Log.e(TAG,"manager is null!!");
        return null;
    }

    ReactContext context = manager.getCurrentReactContext();
    if (context == null) {
        Log.e(TAG,"context is null!!");
        return null;
    }
    return context.getCatalystInstance();
}
 

/** Check whether on not the React Native application is in foreground. */
public static boolean isReactNativeAppInForeground(@NonNull ReactNativeHost reactNativeHost) {
  if (!reactNativeHost.hasInstance()) {
    // If the app was force-stopped the instace will be destroyed. The instance can't be created from a background thread.
    return false;
  }
  ReactContext reactContext = reactNativeHost.getReactInstanceManager().getCurrentReactContext();
  return reactContext != null && reactContext.getLifecycleState() == LifecycleState.RESUMED;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
    return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}
 

@Override
public ReactNativeHost getReactNativeHost() {
  return mReactNativeHost;
}