Formatting date and time (Java)

A problem encountered at work, by the way, record it.

Suppose the value of the obtained time and date is a String type, for example: String time_now = "2018-4-28 17:04:05";

When we need to take the previous date or the later time separately, we need to process:

private String getTime(String end) {
		String time = null;
		if(end == null) {
			return "";
		}else {
		SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
		try {
			Date d1 = df.parse(end);
			time = df.format(d1);
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace ();
		}
		return time;
		}
	}

The standard output of getting the current time from Date is:

Date ss= new Date();

Sat Apr 28 17:17:22 CST 2018 Such data

After such formatting, you will get the standard String type of time:

        SimpleDateFormat format0 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
        String time = format0.format(ss.getTime());
        System.out.println("Format 0: " + time);  
        SimpleDateFormat format1 = new SimpleDateFormat("yyyy year MM month dd day HH hours mm minutes ss seconds");  
        time = format1.format(ss.getTime());  
        System.out.println("Format 1: " + time);  

The output result is: formatted result 0: 2018-04-28 17:19:55
            Formatted result 1: April 28, 2018 17:19:55