String conversion date, the conversion date string

Date format is converted to a string

　　　　　　　　　// Convert the date to a string
		Date d=new Date();
		SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String s=sdf.format(d);
		System.out.println(s);
		
		// convert a string to date
		Date d1=null;
		try {
			d1=sdf.parse(s);
		} catch (ParseException e) {
			e.printStackTrace ();
		}
		System.out.println(d1);