Page through file query (Drive API)

gistfile1.txt

DriveFilesPage page = null;

do
{
  if (page == null)
  {
    page = driveOperations.driveFileQuery().titleIs(folderName).isFolder().parentIs(parentId).getPage();
  }
  else
  {
    page = driveOperations.driveFileQuery().fromPage(page.getNextPageToken()).getPage();
  }
  
  List<DriveFile> childfolders = page.getItems();
  if (!childfolders.isEmpty() && childfolders.size() == 1)
  {
    // Some operation here
  }
  else if (!childfolders.isEmpty() && childfolders.size() == 1)
  {
    // Some operation here
  }
}
while (page.getNextPageToken() != null);