Communication between activity/service and widget provider?

Question

My app has one widget it has 4 buttons when the user clicks buttons on widget I have to send some code to the connected Bluetooth. In my Bluetooth service class I am passing Bluetooth Mac address to connect with external Bluetooth devices. How can I communicate between service and widget or widget to activity in android. If I use getService my Bluetooth would disconnect. Is there any way to call service methods or activity methods in appWidgetProvider class

Answer 1

The best thing you can do in appWidgetProvider is to send messages to your service/activity via intents. You can use the LocalBroadcastManager in support library v4 to broadcast messages internally to your app only. Example:

@Override
public void onCreate(Bundle savedInstanceState) {

  ...

  // Register to receive messages.
  // We are registering an observer (mMessageReceiver) to receive Intents
  // with actions named "custom-event-name".
  LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
      new IntentFilter("custom-event-name"));
}

// Our handler for received Intents. This will be called whenever an Intent
// with an action named "custom-event-name" is broadcasted.
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
  @Override
  public void onReceive(Context context, Intent intent) {
    // Get extra data included in the Intent
    String message = intent.getStringExtra("message");
    Log.d("receiver", "Got message: " + message);
  }
};

@Override
protected void onDestroy() {
  // Unregister since the activity is about to be closed.
  LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
  super.onDestroy();
}

And in your widget provider:

private void sendMessage() {
  Log.d("sender", "Broadcasting message");
  Intent intent = new Intent("custom-event-name");
  // You can also include some extra data.
  intent.putExtra("message", "This is my message!");
  LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}