Best way to compare dates in Android

Your code could be reduced to

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date strDate = sdf.parse(valid_until);
if (new Date().after(strDate)) {
    catalog_outdated = 1;
}

or

SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date strDate = sdf.parse(valid_until);
if (System.currentTimeMillis() > strDate.getTime()) {
    catalog_outdated = 1;
}