Unknowingly, you have introduced two major problems in your code:
- Not using the proper timezone name: The two/three/four letter timezone names (e.g. ET, EST, CEST etc.) are error-prone. The proper way of naming a timezone is Region/City e.g. Europe/London. In most cases, the Region is the name of the continent to which the City belongs.
- Not using
Locale with SimpleDateFormat: A parsing/formatting type e.g. the legacy, SimpleDateFormat or the modern, DateTimeFormatter are Locale-sensitive and therefore you should always use a Locale to avoid surprises. You can check this answer to learn more about it.
Also, note that a java.util.Date object is not a real Date-Time object like the modern Date-Time types; rather, it represents the number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT (or UTC). Since it does not hold any format and timezone information, it applies the format, EEE MMM dd HH:mm:ss z yyyy and the JVM's timezone to return the value of Date#toString derived from this milliseconds value. If you need to print the Date-Time in a different format and timezone, you will need to use a SimpleDateFormat with the desired format and the applicable timezone e.g.
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;
import java.util.TimeZone;
public class Main {
public static void main(String[] args) {
Date date = new Date();
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yy hh:mm a zzz", Locale.ENGLISH);
sdf.setTimeZone(TimeZone.getTimeZone("America/New_York"));
System.out.println(sdf.format(date));
sdf.setTimeZone(TimeZone.getTimeZone("Etc/UTC"));
System.out.println(sdf.format(date));
}
}
A sample output:
05/06/21 08:29 AM EDT
05/06/21 12:29 PM UTC
ONLINE DEMO
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The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone.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*.
A demo using java.time, the modern API:
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 zdtUTC = now.atZone(ZoneId.of("Etc/UTC"));
System.out.println(zdtUTC);
ZonedDateTime zdtNewYork = now.atZone(ZoneId.of("America/New_York"));
System.out.println(zdtNewYork);
}
}
A sample output:
2021-06-05T12:19:58.092338Z
2021-06-05T12:19:58.092338Z[Etc/UTC]
2021-06-05T08:19:58.092338-04:00[America/New_York]
ONLINE DEMO
Need output string in a different format?
You can use DateTimeFormatter for the output string in a different format e.g.
import java.time.Instant;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
Instant now = Instant.now();
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd/MM/uu hh:mm a zzz", Locale.ENGLISH);
ZonedDateTime zdtUTC = now.atZone(ZoneId.of("Etc/UTC"));
System.out.println(dtf.format(zdtUTC));
ZonedDateTime zdtNewYork = now.atZone(ZoneId.of("America/New_York"));
System.out.println(dtf.format(zdtNewYork));
}
}
A sample output:
05/06/21 12:34 PM UTC
05/06/21 08:34 AM EDT
ONLINE DEMO
Here, you can use yy instead of uu but I prefer u to y.
Learn more about java.time, the modern Date-Time API* from Trail: Date Time.
* 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.
