private void favoriteAdd(final ProgressButtonDisposableHandler handler) {
            final IFavoriteCapability connector = (IFavoriteCapability) ConnectorFactory.getConnector(cache);
            if (connector.addToFavorites(cache)) {
                handler.sendTextMessage(MESSAGE_SUCCEEDED, R.string.cachedetails_progress_favorite);
            } else {
                handler.sendTextMessage(MESSAGE_FAILED, R.string.err_favorite_failed);
            }
        }
Add this cache to the favorite list of the user
main/src/main/java/cgeo/geocaching/CacheDetailActivity.java