why following code is not generate proper output base on input date

Question

SimpleDateFormat dateFormat = new SimpleDateFormat("YYYY-MM-dd");
date1 = dateFormat.format(new Date(date));
System.out.println(date+" "+date1);

My input is date = 30-Dec-2019 and the expected output is 2019-12-30

The output I'm getting is 2020-12-30

Do not longer use the old simpledateformat and java.util.Date Api. Use the new java.times.* API. And yyyy instead of YYYY. — Jens, May 05 '20 at 17:26
If you want help with your code using the obsolete API, at least post code that compiles. — David Conrad, May 05 '20 at 17:27
The deprecated `Date(String)` constructor doesn't accept input in that format. — David Conrad, May 05 '20 at 17:31
I recommend (1) Don’t use `SimpleDateFormat` and `Date`. Those classes are poorly designed and long outdated, the former in particular notoriously troublesome. Instead use `LocalDate` and `DateTimeFormatter`, both from [java.time, the modern Java date and time API](https://docs.oracle.com/javase/tutorial/datetime/). (2) Even if you insist on using `Date`, stay far away from the deprecated constructors. They have been deprecated for over 23 years because they work unreliably across time zones. — Ole V.V., May 05 '20 at 17:51

score 1 · Answer 1 · answered May 05 '20 at 17:39

Do not use the outdated date/time API. Do it using modern date/time API as follows:

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;

public class Main {

    public static void main(String[] args) throws Exception {
        DateTimeFormatter inputFormat = DateTimeFormatter.ofPattern("dd-MMM-yyyy");
        DateTimeFormatter outputFormat = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        String strDate = "30-Dec-2019";
        LocalDate date = LocalDate.parse(strDate, inputFormat);
        System.out.println(outputFormat.format(date));
    }
}

Output:

2019-12-30

Check this to learn about the drawbacks of the outdated date/time API and the benefits of modern date/time API.

why following code is not generate proper output base on input date

1 Answers1