Format date in yyyy-MM-dd hh:mm:ss format from whatever format

Question

I am having various date String and want to format in particular format using java

String arr[] = {"Jul 02,2020 ","15-10-2015 10:20:56",&q         


        

Answer 1

I recommend you switch from the outdated and error-prone java.util date-time API to the rich set of modern date-time API. Using DateTimeFormatterBuilder, you can build a format including all expected date-time formats and hour, minute, second defaulting to 0.

Demo

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.time.format.DateTimeFormatterBuilder;
import java.time.temporal.ChronoField;

public class Main {
    public static void main(final String[] args) {
        String arr[] = { "Jul 02,2020 ", "15-10-2015 10:20:56", "2015/10/26 12:10:39", "27-04-2016 10:22:56",
                "April 7, 2020" };
        DateTimeFormatter formatter = new DateTimeFormatterBuilder()
                                        .appendPattern("[MMM d,yyyy]")
                                        .appendPattern("[dd-MM-yyyy HH:mm:ss]")
                                        .appendPattern("[yyyy/MM/dd HH:mm:ss]")
                                        .appendPattern("[dd-MM-yyyy HH:mm:ss]")
                                        .appendPattern("[MMMM d, yyyy]")
                                        .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
                                        .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
                                        .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
                                        .toFormatter();

        for (String s : arr) {
            LocalDateTime ldt = LocalDateTime.parse(s.trim(), formatter);
            System.out.println("LocalDate#toString: " + ldt + ", " + "Formatted: "
                    + ldt.format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")));
        }
    }
}

Output:

LocalDate#toString: 2020-07-02T00:00, Formatted: 2020-07-02 00:00:00
LocalDate#toString: 2015-10-15T10:20:56, Formatted: 2015-10-15 10:20:56
LocalDate#toString: 2015-10-26T12:10:39, Formatted: 2015-10-26 12:10:39
LocalDate#toString: 2016-04-27T10:22:56, Formatted: 2016-04-27 10:22:56
LocalDate#toString: 2020-04-07T00:00, Formatted: 2020-04-07 00:00:00