code: public static File getFullBackupFile(File restoreDir)
     {
        Pattern p = Pattern.compile(".+\\.0");
  
        for (File f : PrivilegedFileHelper.listFiles(restoreDir, new FileFilter()
        {
           public boolean accept(File pathname)
           {
              Pattern p = Pattern.compile(".+\\.[0-9]+");
              Matcher m = p.matcher(pathname.getName());
              return m.matches();
           }
        }))
        {
           Matcher m = p.matcher(f.getName());
           if (m.matches())
           {
              return f;
           }
        }
  
        return null;
     }
docs: Returns file with full backup. In case of RDBMS backup
  it may be a directory.
  
  @param restoreDir
  @return