GMT calculation

November 19, 2009
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http://www.jguru.com/faq/view.jsp?EID=534382 

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Answer

private static final String DATE_FORMAT = "yyyy-MM-dd'T'HH:mm:ss";
/** * @return GMT datetime object as a String
*/
public String getGmtTime(long eventTime) {
TimeZone tz = TimeZone.getTimeZone("GMT:00");
// SimpleDateFormat sdf = new SimpleDateFormat(DATE_FORMAT);
SimpleDateFormat sdf = new SimpleDateFormat();sdf.applyPattern(DATE_FORMAT);
sdf.setTimeZone(tz);
Calendar gmtCalendar = Calendar.getInstance(tz);
gmtCalendar.setTimeInMillis(eventTime);
String stringSDF = sdf.format(gmtCalendar.getTime());
return stringSDF;
} 
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Answer (deprecated)

Create a custom TimeZone and use it for DateFormat.setTimeZone(). This is discussed briefly in the API documentation and shown in the following code.

import java.text.*;
import java.util.*
;public class GMTFmt2
{
public static void main( String[] args )
{
TimeZone tz = TimeZone.getTimeZone("GMT:00");
DateFormat dfGMT = DateFormat.getTimeInstance( DateFormat.LONG );
dfGMT.setTimeZone( tz );
System.out.println( dfGMT.format( new Date() ) );
} // end main
} // End class GMTFmt2
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Answer

You may also want to consider Joda-Time, the alternative to JDK dates – http://joda-time.sourceforge.net Here is how your task would look:

import org.joda.time.*;
import org.joda.time.format.*;
public class GMTFmt3
{
public static void main(String[] args)
{
// Get current time using UTC (same as GMT)
DateTime dt = new DateTime(DateTimeZone.UTC);
// output in long format
System.out.println( DateTimeFormat.longDateTime().print(dt) );
}
}