synchronized (this.getClass())
synchronized (Connection.class)
  public String getHeaderField(String field)  {    try      {	if (!connected)	  connect();	if (field.equals("content-type"))          return guessContentTypeFromName(getJarEntry().getName());	else if (field.equals("content-length"))          return Long.toString(getJarEntry().getSize());	else if (field.equals("last-modified"))	  {	    // Both creating and manipulating dateFormat need synchronization.	    synchronized (this.getClass())	      {		if (dateFormat == null)		  dateFormat = new SimpleDateFormat		    ("EEE, dd MMM yyyy hh:mm:ss 'GMT'",		     new Locale ("En", "Us", "Unix"));        	return dateFormat.format(new Date(getJarEntry().getTime()));	      }	  }      }    catch (IOException e)      {        // Fall through.      }    return null;  }