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Unable to convert UTC to IST, it is still returning me UTC only

I am trying to convert UTC Date to IST. But to my surprise, after converting everything, it is still returning me UTC only. How is it possible?
INPUT:
StartDateTimeUtc='2017-09-15T14:00:00',
EndDateTimeUtc='2017-09-15T15:00:00'
Code:
public static final String DATE_FORMATE_CURRENT = "yyyy-MM-dd'T'HH:mm:ss";
Date meetingStartDate = new SimpleDateFormat(Constants.DATE_FORMATE_CURRENT, Locale.ENGLISH).parse(model.StartDateTimeUtc);
Date meetingEndDate = new SimpleDateFormat(Constants.DATE_FORMATE_CURRENT, Locale.ENGLISH).parse(model.EndDateTimeUtc);
//Convert Date to String
DateFormat df = new SimpleDateFormat(Constants.DATE_FORMATE_CURRENT);
String meetinStartDateString = df.format(meetingStartDate);
String meetingEndDateString = df.format(meetingEndDate);
//Convert String Date to IST
SimpleDateFormat dftwo = new SimpleDateFormat(Constants.DATE_FORMATE_CURRENT);
dftwo.setTimeZone(TimeZone.getTimeZone("Asia/Kolkata"));
Date date = null;
Date datetwo = null;
try {
date = dftwo.parse(meetinStartDateString);
datetwo = dftwo.parse(meetingEndDateString);
} catch (ParseException e) {
e.printStackTrace();
}
dftwo.setTimeZone(TimeZone.getDefault());
String formattedStartDate = dftwo.format(date);
String formattedEndDate = dftwo.format(datetwo);
//Convert String Date back to Date format so that we can pass into Calendar code
Date meetingStartDateFinal = new SimpleDateFormat(Constants.DATE_FORMATE_CURRENT, Locale.ENGLISH).parse(formattedStartDate);
Date meetingEndDateFinal = new SimpleDateFormat(Constants.DATE_FORMATE_CURRENT, Locale.ENGLISH).parse(formattedEndDate);
OUTPUT again in UTC:
Start Date : Fri Sep 15 14:00:00 GMT+05:30 2017
End Date : Fri Sep 15 15:00:00 GMT+05:30 2017

A java.util.Date doesn't have any timezone information. It just contains one value: the number of milliseconds since unix epoch (1970-01-01T00:00Z, or January 1st 1907, at midnight in UTC).
This number of milliseconds is the same, everywhere in the world. What's is different is the corresponding date and time in each timezone. Example: right now, this millis value is 1505481835424, which corresponds, in UTC, to 2017-09-15T13:23:55.424Z. This same value corresponds to 10:23 AM in São Paulo, 18:53 in Kolkata, 14:23 in London and so on. The local date/time is different in each timezone, but the millis value is the same for everyone.
That's why you don't convert a Date itself: the millis value is the same, and there's no need to change it. What you can change is the representation of this date in different timezones.
SimpleDateFormat, by default, uses the JVM default timezone to parse dates. But if you know that the inputs are in a specific zone, you must set in the formatter. So, to parse your inputs, you must do:
String startDateTimeUtc = "2017-09-15T14:00:00";
String endDateTimeUtc = "2017-09-15T15:00:00";
SimpleDateFormat sdf = new SimpleDateFormat( "yyyy-MM-dd'T'HH:mm:ss");
// input is in UTC
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
// parse dates
Date meetingStartDate = sdf.parse(startDateTimeUtc);
Date meetingEndDate = sdf.parse(endDateTimeUtc);
The 2 Date objects above will correspond to 14:00 and 15:00 UTC (which is the same as 19:30 and 20:30 in Kolkata timezone).
But if you just print the Date objects directly (using System.out.println, logging, or even checking their values in a debugger), it'll implicity call the toString() method, which uses the JVM default timezone behind the scenes, resulting in the output you're seeing (Fri Sep 15 14:00:00 GMT+05:30 2017).
If you want to print in a specific format, and in a specific timezone, you'll need another formatter:
// another formatter for output
SimpleDateFormat outputFormat= new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
// output will be in Asia/Kolkata timezone
outputFormat.setTimeZone(TimeZone.getTimeZone("Asia/Kolkata"));
System.out.println(outputFormat.format(meetingStartDate));
System.out.println(outputFormat.format(meetingEndDate));
The output will be:
2017-09-15T19:30:00
2017-09-15T20:30:00
Which corresponds to the same UTC dates in Kolkata timezone.
Just remember: you don't convert the Date's between timezones (because their millis values are "absolute" - they are the same for everyone in the world). You just change the String representation of those dates (the corresponding date/time in a specific timezone).
Java new Date/Time API
The old classes (Date, Calendar and SimpleDateFormat) have lots of problems and design issues, and they're being replaced by the new APIs.
In Android you can use the ThreeTen Backport, a great backport for Java 8's new date/time classes. To make it work, you'll also need the ThreeTenABP (more on how to use it here).
This new API has lots of different date/time types for each situation. In this case, the inputs have date and time, but no timezone information, so first I parse them to a org.threeten.bp.LocalDateTime, using a org.threeten.bp.format.DateTimeFormatter:
// parse the inputs
DateTimeFormatter fmt = DateTimeFormatter.ISO_LOCAL_DATE_TIME;
LocalDateTime startDt = LocalDateTime.parse(startDateTimeUtc, fmt);
LocalDateTime endDt = LocalDateTime.parse(endDateTimeUtc, fmt);
Then I use a org.threeten.bp.ZoneOffset to convert them to UTC, and later a org.threeten.bp.ZoneId to convert this to another timezone. The result will be a org.threeten.bp.ZonedDateTime:
// input is in UTC
ZoneOffset utc = ZoneOffset.UTC;
// convert to Asia/Kolkata
ZoneId zone = ZoneId.of("Asia/Kolkata");
ZonedDateTime start = startDt.atOffset(utc).atZoneSameInstant(zone);
ZonedDateTime end = endDt.atOffset(utc).atZoneSameInstant(zone);
Then I use the same DateTimeFormatter to format the output:
System.out.println(fmt.format(start));
System.out.println(fmt.format(end));
The output is:
2017-09-15T19:30:00
2017-09-15T20:30:00
Note that I don't need to set the timezone in the formatter, because the timezone information is in the objects (they are responsible to do the conversion).

Get XMLGregorianCalendar date in EST time Zone

I am using TimeZone.setDefault(TimeZone.getTimeZone("EST")); to get the time zone EST and it is working fine to me. But sometimes I am getting time zone EDT when no one called this method in my project because of the default JVM time zone.
public getTimeInEST(XMLGregorianCalendar date) {
TimeZone.setDefault(TimeZone.getTimeZone("EST"));
DateFormat formatter = new SimpleDateFormat("dd MMM yyyy HH:mm:ss z");
formatter.setTimeZone(TimeZone.getTimeZone("EST"));
String newTime = formatter.format(date.toGregorianCalendar().getTime());
Date newDate = null;
try {
newDate = formatter.parse(newTime);
System.out.println("ESTDate : " + newDate)
} catch(ParseException e) {
System.out.println(e.getMessage);
}
}
Is there any other way where I get XMLGregorianCalendar date in EST time zone without using TimeZone.setDefault(TimeZone.getTimeZone("EST"))?

I suspect you should just pass the time zone to toGregorianCalendar. I'd also strongly recommend using full time zone IDs rather than abbreviations - after all, I suspect you really want Eastern time (EST and EDT) rather than just EST.
Also, there's no need to format a string value and then parse it - you can just use Calendar.getTime():
// Possibly...
public Date toDate(XMLGregorianCalendar date) {
TimeZone zone = TimeZone.getTimeZone("America/New_York");
Calendar calendar = date.toGregorianCalendar(zone, Locale.US, null);
return calendar.getTime();
}
Note that a Date value doesn't have a time zone - it's just an instant in time. The return value of Date.toString() is misleading in that it always uses the system default time zone, but there's no such thing as "a Date in the Eastern time zone".
I've included the "possible" in the comment as it's not really clear what you're trying to achieve here. This code is only useful if the XMLGregorianCalendar specifies the date/time but no time zone, and you want to assume it actually represents a value in the Eastern time zone, and convert that to an instant in time. Is that what you want?

Java: Compare dates on same timezone

Given:
SimpleDateFormat sd = new SimpleDateFormat ("yy-MM-dd hh:mm:ss.SSS");
sd.setTimeZone(TimeZone.getTimeZone("GMT"));
Date d = sd.parse("a date similar to now on local computer");
if I compare d.getTime() with new Date().getTime(), the values are different with more than one hour. Why?

Check your timezones. You are comparing a time that isn't in GMT.

You're explicitly setting your SimpleDateFormat to parse in GMT, which means that when you parse the current clock time, you're getting the moment of time when that time occurred, in the GMT time zone. If you're not in the GMT time zone, that won't be "now".

Date objects don't know anything about timezones - there is no explicit timezone information in a Date object. A Date object represents an "absolute" moment in time (it's a timestamp). This means you should not think of a Date object as "a date in a certain timezone" - it has no timezone.
Suppose that from some source you get a String that contains a date and time, without an explicit timezone mentioned in it, for example: 2014-12-16 17:30:48.382. Suppose that you know that this date and time is in the GMT timezone.
You could then parse it to a Date object with an appropriate SimpleDateFormat object:
DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
// Set the timezone of the SimpleDateFormat to GMT, because you know the string
// should be interpreted as GMT
fmt.setTimeZone(TimeZone.getTimeZone("GMT"));
// Parse the String into a Date object
Date dateTime = fmt.parse("2014-12-16 17:30:48.382");
// Date object which is set to "now"
Date now = new Date();
// Compare it to "now"
if (dateTime.before(now)) {
System.out.println("The specified date is in the past");
} else if (dateTime.after(now)) {
System.out.println("The specified date is in the future");
} else {
System.out.println("The specified date is now");
}
If you want to print the date in a certain timezone, then do so by formatting it with a SimpleDateFormat set to the appropriate timezone.
DateFormat outfmt = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS z");
outfmt.setTimeZone(TimeZone.getTimeZone("EDT"));
// Will print dateTime in the EDT timezone
System.out.println(outfmt.format(dateTime));

Date getTime() from Calendar in specific timezone

I have this code below:
Date now = CalendarUtils.getCalendar(getDefaultTimeZone())
.getTime();
The CalendarUtils class has the below methods
public static Calendar getCalendar(final TimeZone tz) {
return getCalendar(CalendarUtils.getDate(), tz);
}
public static Calendar getCalendar(final Date time, final TimeZone tz) {
final GregorianCalendar calendar = new GregorianCalendar();
calendar.setTimeZone(tz);
calendar.setTime(time);
return calendar;
}
public static Date getDate() {
return CalendarUtils.getDate(System.currentTimeMillis());
}
Where the getDefaultTimeZone() returns a timezone object in a specific timezone. Let's say Europe/Madrid.
However my application is running on a server in Rome.
The problem is that the code above is used to get the local time of Madrid. So at 12:30 am in Rome on Aug. 8th it is still 11:30 pm Aug. 7th in Madrid.
When I use
Date startOfDay = DateUtils.truncate(now, Calendar.DATE);
I would expect Aug. 7th 00:00:00 instead I get Aug 8th 00:00:00
I have read how Date returns the Millis from the Epoch but I would expect that it would return the millis from the Epoch of the date I ask from the Calendar.
When I use the query below at 12:30 am Aug 8th Rome time utilizing the two dates (now and startOfDay) I get results for the 8th of Aug instead the 7th (which is the local time in Madrid).
public BigInteger getSumForDates(Date fromDate, Date toDate) {
Session session = sessionFactory.openSession();
BigInteger sum;
try{
sum = (BigInteger)session
.createSQLQuery(
"SELECT SUM(column) FROM table
WHERE (column2 at time zone vas_tz()) >=:fromDate
AND (column2 at time zone vas_tz()) < :toDate")
.setTimestamp("fromDate", fromDate)
.setTimestamp("toDate", toDate).uniqueResult();
}catch (final HibernateException e){
LOGGER.error(e.getMessage());
throw new ProjectRuntimeException();
}finally{
session.close();
}
EDIT
The DateUtils is the one from package org.apache.commons.lang.time;
public static Date truncate(Date date, int field) {
if (date == null) {
throw new IllegalArgumentException("The date must not be null");
}
Calendar gval = Calendar.getInstance();
gval.setTime(date);
modify(gval, field, MODIFY_TRUNCATE);
return gval.getTime();
}
When I say to return the millis for the date I have asked the Calendar for, I meant that if the calendar has supplied Aug 7th 11:30 pm (since I provided a timezone) then I would expect the millis from the Epoch until Aug 7th 11:30 adjusted for that timezone. Is this an incorrect expectation?

I have read how Date returns the Millis from the Epoch but I would expect that it would return the millis from the Epoch of the date I ask from the Calendar.
Then your expectation is incorrect - or you're not expressing your expectation clearly. There's only one Unix epoch: it's midnight UTC. A Date has no concept of a time zone - it's just the number of milliseconds since the Unix epoch.
It's not clear what your DateUtils class is, but anything which claims to truncate a Date to a day without specifying a time zone is somewhat dubious.
I would strongly advise you to use Joda Time or the Java 8 java.time classes - they're much simpler to work with than java.util.*. If you must use java.util.Date and java.util.Calendar, you'll need to work out which time zone you're interested, and specify that appropriately - using Calendar, not Date - when performing operations such as "truncate to day".

SimpleDateFormat returns wrong date value during parse

I m facing a problem:I want to get current time of GMT TimeZone in long.
I m using the following code as given below:
TimeZone timeZoneGmt = TimeZone.getTimeZone("GMT");
long gmtCurrentTime = getCurrentTimeInSpecificTimeZone(timeZoneGmt);
public static long getCurrentTimeInSpecificTimeZone(TimeZone timeZone) {
Calendar cal = Calendar.getInstance();
cal.setTimeZone(timeZone);
long finalValue = 0;
SimpleDateFormat sdf = new SimpleDateFormat(
"MMM dd yyyy hh:mm:ss:SSSaaa");
sdf.setTimeZone(timeZone);
Date finalDate = null;
String date = sdf.format(cal.getTime());
try {
finalDate = sdf.parse(date);
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finalValue = finalDate.getTime();
return finalValue;
}
As given in, above method
while formatting
String date = sdf.format(cal.getTime());
I m getting correct current time in GMT but as i do parsing by following code:
finalDate=sdf.parse(date);
Date got changed from current GMT time to 15:35:16 IST 2013 that is current time of my system.
I tried with Calendar as well in another way:
TimeZone timeZoneGmt=TimeZone.get("GMT");
Calendar calGmt = Calendar.getInstance();
calGmt.setTimeZone(timeZoneGmt);
long finalGmtValue = 0;
finalGmtValue = calGmt.getTimeInMillis();
System.out.println("Date......" + calGmt.getTime());
but still getting date as current time of my System Thu Jan 23 15:58:16 IST 2014 Not getting GMT current time.

You've misunderstood how Date works. A Date doesn't have a time zone - if you use Date.toString() you'll always see the default time zone. The long value in a Date is purely the number of milliseconds since the Unix epoch: it doesn't have any concept of time zone or calendar system.
If you want to represent a date and time in a particular time zone and calendar, use Calendar instead - but for getting "the current date and time as a long" you can just use System.currentTimeMillis(), which again does not have anything to do with the system time zone.
Additionally, even if you did want to do manipulation like this, you shouldn't be using string conversions. You're not conceptually performing any string conversions, so why introduce them?
If your aim is to display (as a string) the current date and time in a particular time zone, you should just use something like:
Date date = new Date(); // This will use the current time
SimpleDateFormat format = new SimpleDateFormat(...); // Pattern and locale
format.setTimeZone(zone); // The zone you want to display in
String formattedText = format.format(date);
When working with date and time APIs - particularly bad ones like the Java Calendar/Date API - it's very important that you understand exactly what each value in your system represents.