How to convert java.util.Date to java.time.LocalDate and preserve date/time

Question

I'm trying to convert a java.util.Date to java.time.LocalDate:

[java.util.Date instance].toInstant().atZone(ZoneId.systemDefault()).toLocalDate();

However, there is a case when [java.util.Date instance] has day time of for example: 22:25 and I choose ZoneId like this for example: ZoneId.of("Asia/Singapore").

The outcoming LocalDate will have different day (because that zone adds +6 hrs) as for example Europe/Minsk:

printing java.util.Date: Thu Mar 04 22:25:00 CET 2021
printing converted java.util.Date to java.time.LocalDate with Europe/Minsk: 2021-03-04
printing converted java.util.Date to java.time.LocalDate with Asia/Singapore: 2021-03-05

and I want to preserve same date in the resulting LocalDate's as in that Date instance. Some approaches how to solve this? I guess there could be several ways.

carlosvin · Accepted Answer · 2021-03-05T10:53:22.207

4

You can just convert it to instant, set a time zone to UTC, because java.util.Date is using UTC.

public static LocalDate convert (Date date) {
    return date.toInstant()
      .atZone(ZoneId.of("UTC"))
      .toLocalDate();
}

edited Mar 05 '21 at 10:53

answered Mar 05 '21 at 10:46

carlosvin

979
9
22

Arvind Kumar Avinash · Answer 2 · 2021-03-05T10:44:41.637

Instant always gives you date-time in UTC and if you want to maintain the same date, you need to use the zone offset of UTC.

Demo:

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.util.Date;
import java.util.Locale;

public class Main {
    public static void main(String[] args) throws ParseException {
        String strDateTime = "10/02/2021 22:25";
        SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm", Locale.ENGLISH);
        Date date = sdf.parse(strDateTime);
        Instant instant = date.toInstant();
        ZonedDateTime zdt = instant.atZone(ZoneOffset.UTC);
        LocalDate localDate = zdt.toLocalDate();
        System.out.println(localDate);
    }
}

Output:

2021-10-02

Learn more about the modern date-time API from Trail: Date Time.

^{The java.util date-time API and their formatting API, SimpleDateFormat are outdated and error-prone. It is recommended to stop using them completely and switch to the modern date-time API. For any reason, if you have to stick to Java 6 or Java 7, you can use ThreeTen-Backport which backports most of the java.time functionality to Java 6 & 7. If you are working for an Android project and your Android API level is still not compliant with Java-8, check Java 8+ APIs available through desugaring and How to use ThreeTenABP in Android Project.}

You were faster. Right, the `ZoneId.systemDefault()` is location specific so `ZoneOffset.UTC` is a good choice to understand the `LocalDate` same no matter where are we located. — Nikolas Charalambidis, Mar 05 '21 at 10:43

score 1 · Answer 3 · answered Mar 05 '21 at 10:36

1

You could simply copy the values of Date to LocalDate without transforming the data:

LocalDate.of(date.getYear(), date.getMonth()+1, date.getDate());

answered Mar 05 '21 at 10:36

Benjamin M

23,599
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121
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The `getXxx` methods of date have been deprecated for 24 years. For a good reason: they work unreliably across time zones. Don’t do it this way. – Ole V.V. Mar 07 '21 at 11:08

score 0 · Answer 4 · answered Mar 07 '21 at 11:12

0

I am sorry, you are asking the impossible. Despite its name the outdated Date class does not represent a date. It represents a point in time. At that point in time there could easily be two different dates in Singapore and Minsk. There is no such thing as to preserve same date since you didn’t have a date from the outset.

answered Mar 07 '21 at 11:12

Ole V.V.

81,772
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If you think my question is asked wrong, please propose an edit. – Wortig Mar 07 '21 at 12:36
1

I think the question is fine as it stands. It’s a common mistake to think that you can get an unambiguous date from a `Date`. So your question and my answer can help clear up for future readers that it isn’t so. – Ole V.V. Mar 07 '21 at 13:27

How to convert java.util.Date to java.time.LocalDate and preserve date/time

4 Answers4