Google Drive API v3返回文件夹总数

Question

我想获取一个文件夹中所有文件的数量。

public List getList(String id, Integer page, Integer limit) throws GeneralSecurityException, IOException {

    final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();

    Drive service = new Drive.Builder(HTTP_TRANSPORT, driveQuickstart.JSON_FACTORY, driveQuickstart.getCredentials(HTTP_TRANSPORT))
            .setApplicationName(driveQuickstart.APPLICATION_NAME)
            .build();

    String q = "trashed = false and '" + id + "' in parents ";

    FileList result = service.files().list()
            .setQ(q)
            .setFields("*")
            .setOrderBy("mimeType")
            .setPageSize(limit)
            .execute();

    List<File> files = result.getFiles();
    if (files == null || files.isEmpty()) {
        System.out.println("No files found.");
    } else {
        System.out.println("Files:");
        for (File file : files) {
            System.out.printf("%s %s (%s) (%s)\n", file.getName(), file.getFullFileExtension(), file.getId(), file.getWebViewLink());
        }
        System.out.println(result.getFiles());
    }

    return files;
}

如果setPageSize，如何返回文件数