@NonNull
    public static Set<String> getGeocodes(@NonNull final Collection<Geocache> caches) {
        final Set<String> geocodes = new HashSet<>(caches.size());
        for (final Geocache cache : caches) {
            final String geocode = cache.getGeocode();
            if (StringUtils.isNotBlank(geocode)) {
                geocodes.add(geocode);
            }
        }
        return geocodes;
    }
Get the geocodes of a collection of caches.

@param caches a collection of caches
@return the non-blank geocodes of the caches
main/src/main/java/cgeo/geocaching/models/Geocache.java