ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archives contents. Here Mudassar Ahmed Khan has explained how to upload and save files to server folder or directory on disk and then retrieve and display the files as list in ASP.Net GridView control. Im new to Java EE, and I want to display in a webpage a list of PDF thumbnails.A quote from the Javadoc of File.listFiles(). returns null if this abstract pathname does not denote a directory, or if an I/O error occurs. Express.