Javax Rest API dateformat on result JSON-CodePudding

Initially, the SpringFramework WAR application was deployed in a Server in which date format in JSON Result Oct 27, 2021 11:23:48 AM even in my local the same.

But the same application is deployed into a new server, now the date format in the result is quite different Oct 27, 2021, 3:38:02 PM Extra comma has been added after the year.

the old server is EST timezone, now the new server is UTC timezone. Without changing time zone What should I do at the code level?

What is the issue? how can I have the same date format as in Old Server?

CodePudding user response：

Try with ZonedDateTime.

LocalDateTime localDateTime = LocalDateTime.now();
ZonedDateTime zonedDateTime = ZonedDateTime.of(localDateTime, ZoneId.of("UTC"));
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("MMM dd, yyyy HH:mm:ss");
String formattedString = zonedDateTime.format(formatter);

CodePudding user response：

What is the issue?

A java.util.Date object simply represents an instant on the timeline — a wrapper around the number of milliseconds since the UNIX epoch (January 1, 1970, 00:00:00 GMT). Since it does not hold any Timezone and Locale information, its toString function applies the JVM's Timezone and Locale to return a String in the format, EEE MMM dd HH:mm:ss zzz yyyy, derived from this milliseconds value. To get the String representation of the java.util.Date object in a different format, Timezone and Locale, you need to use SimpleDateFormat with the desired format and the applicable Timezone and Locale e.g.

Date date = new Date();

SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSXXX", Locale.ENGLISH);

sdf.setTimeZone(TimeZone.getTimeZone("America/New_York"));
String strDateNewYork = sdf.format(date);
System.out.println(strDateNewYork);

sdf.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
String strDateUtc = sdf.format(date);
System.out.println(strDateUtc);

So you see different representations of the same instant i.e.

Oct 27, 2021 11:23:48 AM at America/New_York = Oct 27, 2021, 3:38:02 PM at UTC

because your server is applying the server's timezone by default. If you want the values to be always in a fixed Timezone, specify the same explicitly as shown above.

how can I have the same date format as in Old Server?

If you want the values to be always in a fixed Locale, specify the same explicitly as shown above.

Switch to `java.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^*.

You can use java.time.Instant whose toString method uses ISO-8601 representation and therefore the output remains the same irrespective of the timezone setting of the server.

Demo:

import java.time.Instant;

public class Main {
    public static void main(String[] args) {
        Instant now = Instant.now();
        System.out.println(now);
    }
}

If you want to display this instant in different timezones, you can obtain the respective ZonedDateTime by using Instant.atZone.

Demo:

import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;

public class Main {
    public static void main(String[] args) {
        Instant now = Instant.now();
        System.out.println(now);

        ZonedDateTime zdtNewYork = now.atZone(ZoneId.of("America/New_York"));
        System.out.println(zdtNewYork);

        ZonedDateTime zdtIndia = now.atZone(ZoneId.of("Asia/Kolkata"));
        System.out.println(zdtIndia);
    }
}

Learn more about the modern Date-Time API from Trail: Date Time. Check this answer and this answer to learn how to use java.time API with JDBC.

^{* 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. Note that Android 8.0 Oreo already provides support for java.time.}

Switch to java.time:

Switch to `java.time`: