@Nullable
    public static String getDisplaynameForMap(final Uri uri) {
        String f = uri.getLastPathSegment();
        if (f != null) {
            f = f.substring(f.lastIndexOf('/') + 1) + INFOFILE_SUFFIX;
            final DownloadedFileData temp = readData(PersistableFolder.OFFLINE_MAPS.getFolder(), f);
            if (temp != null && StringUtils.isNotBlank(temp.displayName)) {
                return temp.displayName;
            }
        }
        return null;
    }
returns a list of downloaded offline files from requested source which are still available in the local filesystem
main/src/main/java/cgeo/geocaching/downloader/CompanionFileUtils.java