You can use TextUtils utility method like this,

if (!TextUtils.isEmpty(content_id) && TextUtils.isDigitsOnly(content_id)) {
    ids[0] = Integer.parseInt(content_id);
} else {
    ids[0] = 0;
}
and while setting content_id you can set like this, content_id = message.getContentId().toString(); instead of content_id.valueOf(message.getContentId().toString()) ;