code: public static void touch(File f) throws IOException
  	{
  		if (f.createNewFile())
  		{
  			// The modify time is already set
  		}
  		else
  		{
  			boolean success = f.setLastModified(System.currentTimeMillis());
  
  			if (!success)
  				log.warn("[FileHelper] {touch} Failed to update modify time on " + f);
  		}
  	}
docs: Creates/updates a file with the modify date set to now
  
  @param f