Listening to MEDIA volume changes has been working for me perfectly.

But now, I need to detect when a user adjusts the Ring & notification volume via Sound & vibration touch sliders on the smartphone’s screen.

For that, I resorted to ContentObserver and implemented:

import android.content.Context;
import android.database.ContentObserver;
import android.media.AudioManager;
import android.net.Uri;
import android.os.Handler;

public class VolumeObserver extends ContentObserver {
    private final Context context;
    private int lastRingVolume, lastNotificationVolume;

    public VolumeObserver(Handler handler, Context context) {
        super(handler);
        this.context = context;
        AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        lastRingVolume = audioManager.getStreamVolume(AudioManager.STREAM_RING);
        lastRingVolume = audioManager.getStreamVolume(AudioManager.STREAM_NOTIFICATION);
    }

    @Override
    public void onChange(boolean selfChange, Uri uri) {
        super.onChange(selfChange);
        if (uri != null && uri.toString().contains("volume")) {
            AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
            int currentRingVolume = audioManager.getStreamVolume(AudioManager.STREAM_RING);
            int currentNotificationVolume = audioManager.getStreamVolume(AudioManager.STREAM_NOTIFICATION);

            if (currentRingVolume != lastRingVolume || currentNotificationVolume != lastNotificationVolume) {
                Log.v("TAG", "ringVolume: " + lastRingVolume + "-->" + currentRingVolume + ", notificationVolume: " + lastNotificationVolume + "-->"  + currentNotificationVolume);
                lastRingVolume = currentRingVolume;
                lastNotificationVolume = currentNotificationVolume;
            }
            else {
                Log.w("TAG", "ringVolume: " + lastRingVolume + "===" + currentRingVolume + ", notificationVolume: " + lastNotificationVolume + "==="  + currentNotificationVolume);
            }
        }
    }
}

Including the proper register/unregister in the app’s main activity.

The problem with my implementation is those events are only received when I press the volume UP/DOWN buttons (correspond to KEYCODE_VOLUME_UP and `KEYCODE_VOLUME_DOWN). That is, at that point there is no chance for the RING volume to change, because it can only change later, when the Sound & vibration settings screen is displayed:

I tried to resort to a BroadcastReceiver based implementation, but I am getting the same behavior: Events are only received on the hardware key press.

I am therefore out of ideas, other then inefficiently polling AudioManager.getStreamVolume(AudioManager.STREAM_RING) …

Am I missing something? Is polling really the only way to monitor Ring & notification volume slider changes?