// references internal ContentObserver class
SettingsObserver observer = new SettingsObserver(new Handler());
// start watching for changes
observer.observe();
// where we do our work
updateSettings();

// Anonymous inner class to handle watching Uris
    class SettingsObserver extends ContentObserver {
        SettingsObserver(Handler handler) {
            super(handler);
        }

        void observe() {
            ContentResolver resolver = mContext.getContentResolver();
            // set our watcher for the Uri we are concerned with
            resolver.registerContentObserver(
                    Settings.System.getUriFor(Settings.System.MY_SUPER_SWEET_MOD_0),
                    false, // only notify that Uri of change *prob won't need true here often*
                    this); // this innerclass handles onChange

            // another watcher
            resolver.registerContentObserver(Settings.System.getUriFor(
                    Settings.System.MY_SUPER_SWEET_MOD_1), false, this);
        }

        @Override
        public void onChange(boolean selfChange) {
            // if changes occurred in either of the watched Uris updateSettings()
            // updateSettings() is a normal void method that will be called to handle all changes
            // or you could just do your work here but presumable the same work will need to be done
            // on load of your class as well... but you get the picture
            updateSettings();
        }
    }

    private void updateSettings() {
        // do work
    }