Monitor Android system settings values

Question

I want to watch a system setting and get notified when its value changes. The Cursor class has a setNotificationUri method which sounded nice, but it doesn't work and coding it also feels strange... Thats what I did:

    // Create a content resolver and add a listener
    ContentResolver resolver = getContentResolver();
    resolver.addStatusChangeListener(ContentResolver.SYNC_OBSERVER_TYPE_SETTINGS | ContentResolver.SYNC_OBSERVER_TYPE_PENDING | ContentResolver.SYNC_OBSERVER_TYPE_ACTIVE, new MyObserver());

    // I somehow need to get an instance of Cursor to use setNotificationUri in the next step...
    Cursor cursor2 = resolver.query(Settings.System.CONTENT_URI, null, null, null, null);

    // For testing purposes monitor all system settings
    cursor2.setNotificationUri(resolver, Settings.System.CONTENT_URI);

The listener:

public class MyObserver implements SyncStatusObserver {

public void onStatusChanged(int which) {
    Log.d("TEST", "status changed, which = " + which);

}
}

Well, obviously the listener gets never called, I can't find an entry with the specified TEST tag in logcat ): (For testing I manually changed the brightness setting from manual to automatic in the android settings menu). Any hint what I am doing wrong? Any other, better way to monitor Android system settings?

Thanks for any hint!

Answer 1

Here's some example code:

ContentResolver contentResolver = getContentResolver();
Uri setting = Settings.System.getUriFor(Settings.System.ACCELEROMETER_ROTATION);

// Make a listener
ContentObserver observer = new ContentObserver(new Handler()) {
    @Override
    public void onChange(boolean selfChange) {
        super.onChange(selfChange);
    }

    @Override
    public boolean deliverSelfNotifications() {
        return true;
    }
};

// Start listening
contentResolver.registerContentObserver(setting, false, observer);

// Stop listening
contentResolver.unregisterContentObserver(observer);

Check out the documentation for any of these methods for more details.

Answer 2

here is how it can be done, works great: How to implement a ContentObserver for call logs. note than some settings are first written / reallly changed when the user presses the back key in the system preference screen where he changed something!