A java.util.Date object simply 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 timezone information, its toString function applies the JVM's timezone 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 and timezone, you need to use SimpleDateFormat with the desired format and the applicable timezone.
Apart from this, there are a couple of problems with your code:
- Use
H instead of h for the 24-Hour format. The letter, h is used for the 12-Hour format (i.e. with AM/PM marker).
- Even though
MMM works for parsing the long name of the month (e.g. January) with SimpleDateFormat, it is meant for the 3-letter month name (e.g. Jan). If you try doing it with the modern Date-Time API, you will be greeted with the DateTimeParseException. You should use MMMM for the long name of the month.
Demo incorporating these points:
import java.text.ParseException;
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) throws ParseException {
String strDateTime = "31 October 2011 11:19:56 GMT";
SimpleDateFormat sdf = new SimpleDateFormat("dd MMMM yyyy HH:mm:ss z", Locale.ENGLISH);
sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
Date date = sdf.parse(strDateTime);
String strDate = sdf.format(date);
System.out.println(strDate);
// Some other format
sdf = new SimpleDateFormat("MMMM dd HH:mm:ss z yyyy", Locale.ENGLISH);
sdf.setTimeZone(TimeZone.getTimeZone("GMT"));
strDate = sdf.format(date);
System.out.println(strDate);
// The last format with some other timezone
sdf.setTimeZone(TimeZone.getTimeZone("America/New_York"));
strDate = sdf.format(date);
System.out.println(strDate);
}
}
Output:
31 October 2011 11:19:56 GMT
October 31 11:19:56 GMT 2011
October 31 07:19:56 EDT 2011
ONLINE DEMO
Switch to java.time API.
The java.util Date-Time API and their formatting API, SimpleDateFormat are outdated and error-prone.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*.
Solution using java.time, the modern Date-Time API:
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Locale;
public class Main {
public static void main(String[] args) {
String strDateTime = "31 October 2011 11:19:56 GMT";
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd MMMM uuuu HH:mm:ss z", Locale.ENGLISH);
ZonedDateTime zdt = ZonedDateTime.parse(strDateTime, dtf);
System.out.println(zdt);
// Some other format
DateTimeFormatter dtfAnother = DateTimeFormatter.ofPattern("MMMM dd HH:mm:ss z uuuu", Locale.ENGLISH);
String strDate = dtfAnother.format(zdt);
System.out.println(strDate);
}
}
Output:
2011-10-31T11:19:56Z[GMT]
October 31 11:19:56 GMT 2011
ONLINE DEMO
The Z in the output is the timezone designator for zero-timezone offset. It stands for Zulu and specifies the Etc/UTC timezone (which has the timezone offset of +00:00 hours).
Learn more about 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.
