Develop Reference

Java date parsing not working for ET timezone while working for IST

I am trying to parse the String to date. String having date format as
"dd-MMM-yyyy Z" and String having value "12-DEC-2018 ET". Its giving the error
java.text.ParseException: Unparseable date: "12-DEC-2018 ET".
The same code is working for String having value "12-DEC-2018 IST".
below is the code snippet:
public static void main(String[] args) throws ParseException {
String dateInputIST ="12-DEC-2018 IST";
String dateInputET ="12-DEC-2018 ET";
SimpleDateFormat sdfmt1 = new SimpleDateFormat("dd-MMM-yyyy Z");
SimpleDateFormat sdfmt2= new SimpleDateFormat("dd/MM/yyyy");
Date dDate = sdfmt1.parse( dateInputIST );
String strOutput = sdfmt2.format( dDate );
System.out.println(strOutput);
Date etDate = sdfmt1.parse(dateInputET);
strOutput = sdfmt2.format(etDate);
System.out.println(strOutput);
}
Could someone please help. I needed to parse the time in any timezone.
Thanks,
Navin

Change
String dateInputET ="12-DEC-2018 ET";
to
String dateInputET ="12-DEC-2018 EDT";
'ET' is not a recognized time zone.

Pseudo-zones
ET, EST, and IST are not actually time zones. Those 2-4 letter pseudo-zones are not standardized and are not even unique! For example, IST can mean India Standard Time, Ireland Standard Time, Iceland Standard Time, and more.
Real time zone names take the format of Continent/Region such as Africa/Tunis.
Date & zone, separately
Date with time zone has no real meaning.
Handle the date as a LocalDate object.
String input = "12-DEC-2018"
DayeTimeFormatter f = DateTimeFormatter.ofPattern( "dd-MM-uuuu" , Locale.US ) ;
LocalDate ld = LocalDate.parse( input , f ) ;
Handle your desired time zone separately, as a ZoneId object.
ZoneId zNewYork = ZoneId.of( "America/New_York" ) ;
To combine, determine the first moment of the day.
ZonedDateTime zdtNewYork = ld.atStartOfDay( z ) ;
Generate text representing that moment in standard ISO 8601 format extended to append the name of the time zone in square brackets.
To see that same moment in UTC, extract a Instant.
Instant instant = zdtNewYork.toInstant() ;
Adjust into another zone.
ZonedDateTime zdtKolkata = instant.atZone( ZoneId.of( "Asia/Kolkata" ) ) ;
To focus on the date only, get a LocalDate for the day of that same moment when viewed through the lens of the wall-clock time used in India.
LocalDate ldKolkata = zdtKolkata.toLocalDate() ;
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, Java SE 11, and later - Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Most of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

java.time
DateTimeFormatter dateZoneFormatter = new DateTimeFormatterBuilder()
.parseCaseInsensitive()
.appendPattern("dd-MMM-uuuu v")
.toFormatter(Locale.ENGLISH);
String dateInputIST ="12-DEC-2018 IST";
String dateInputET ="12-DEC-2018 ET";
TemporalAccessor parsed = dateZoneFormatter.parse(dateInputIST);
System.out.println("Date: " + LocalDate.from(parsed) + " Time zone: " + ZoneId.from(parsed));
parsed = dateZoneFormatter.parse(dateInputET);
System.out.println("Date: " + LocalDate.from(parsed) + " Time zone: " + ZoneId.from(parsed));
On my computer the output from this snippet was:
Date: 2018-12-12 Time zone: Atlantic/Reykjavik
Date: 2018-12-12 Time zone: America/New_York
Format pattern letter v is for the generic time-zone name, that is, the name that is the same all year regardless of summer time (DST), for example Eastern Time or short ET.
If you want to control the interpretation of ambiguous time zone abbreviations (of which there are a lot), you may use the two-arg appendGenericZoneText​(TextStyle, Set<ZoneId>) where the second argument contains the preferred zones. Still better if there is a way for you to avoid relying on time zone abbreviations altogether since, as I said, they are very often ambiguous.
I am not sure what sense a date with a time zone makes, though.
As an additional point, always specify locale for your formatters so they will also work if the default locale is changed or one day your program runs in a JVM with a different default locale.
Avoid SimpleDateFormat and Date
I don’t think SimpleDateFormat will be able to parse your string. It’s just the same since that class is already long outdated and is renowned for being troublesome, so you should never want to use it anyway.

Getting unable to parse date exception

I have date and time on string type 20/03/2018, 18:20:44 Is it possible to change it to date format in java? I tried this code:
public static Date getDate(String dateString) {
DateFormat formatter = new SimpleDateFormat("dd/mm/yyyy hh:mm:ss");
formatter.setTimeZone(TimeZone.getTimeZone("PST"));
try {
Date date = formatter.parse(dateString);
return date;
} catch (ParseException e) {
logger.error("error while parsing milliseconds to date" + dateString, e);
}
return null;
}
I get unable to parse exception and returned with null

You've used the wrong string replacements inside your simple date format, it should be dd/MM/yyyy, HH:mm:ss. Note the capitalisation of the HH as well, your time is in 24 hour format so it must be HH over hh
So with the applied changes your code will look like this:
public static Date getDate(String dateString) {
DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy, HH:mm:ss");
formatter.setTimeZone(TimeZone.getTimeZone("PST"));
try {
return formatter.parse(dateString);
} catch (ParseException e) {
logger.error("error while parsing milliseconds to date" + dateString, e);
}
return null;
}
Read more on the various patterns available here, as an aside it is generally recommended to use the ISO 8601 format for dates, so yours would be yyyy-MM-ddTHH:mm:ss

You should use the same format with input string:
DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy, hh:mm:ss");

You did two mistakes :
mm represents minutes. MM represents months.
But You specify mm in the month part of the date format.
the coma character : , provided in the input has also to be present in the date format.
So with a String input in this form : "20/03/2018, 18:20:44", you should use this DateFormat :
DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy, hh:mm:ss");

tl;dr
Your formatting pattern was incorrect, using the wrong case and omitting the comma.
Also, you are using troublesome classes supplanted years ago by java.time classes.
LocalDateTime.parse( // Create a `LocalDateTime` object as the input string lacks any time zone or offset-from-UTC.
"20/03/2018, 18:20:44" ,
DateTimeFormatter.ofPattern( "dd/MM/uuuu, HH:mm:ss" ) // Define a formatting pattern to match the input.
)
.atZone( // Assign a time zone to the `LocalDateTime` to create a `ZonedDateTime` object.
ZoneId.of( "America/Los_Angeles" ) // Specify time zone to be assigned. Always use proper zone names `continent/region`; never use 3-4 character pseudo-zones.
)
2018-03-20T18:20:44-07:00[America/Los_Angeles]
java.time
You are using troublesome old date-time classes that are now legacy, supplanted by the java.time classes.
Parse your string as a LocalDateTime since it lacks an indicator of time zone or offset-from-UTC.
String input = "20/03/2018, 18:20:44" ;
DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd/MM/uuuu, HH:mm:ss" ) ;
LocalDateTime ldt = LocalDateTime.parse( input , f ) ;
ldt.toString(): 2018-03-20T18:20:44
Lacking a time zone or offset-from-UTC means that this does not represent a moment, is not a point on the timeline. Without the context of a zone/offset, this represents only a vague idea about potential moments along a range of 26-27 hours.
Apparently you are certain this input was actually meant to be in certain time zone. Apply a ZoneId to this LocalDateTime to get a ZonedDateTime object.
Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).
ZoneId z = ZoneId.of( "America/Los_Angeles" ) ;
ZonedDateTime zdt = ldt.atZone( z ) ;
Conversion
Best to avoid the troublesome legacy classes. But if you must produce a java.util.Date to inter-operate with old code not yet updated for java.time, you can convert. To convert back and forth, call new methods on the old classes.
A java.util.Date represents a point on the timeline in UTC, with a resolution of milliseconds. So its replacement in java.time is Instant. An Instant is also a point on the timeline in UTC, with a finer resolution of nanoseconds. To get to a Date, we need an Instant, which we can pull from our ZonedDateTime.
Instant instant = zdt.toInstant() ; // Same moment, same point on the timeline, different wall-clock time.
Now we can get the legacy class object, Date, by calling Date.from.
java.util.Date date = Date.from( instant ) ; // Do this only if you *must* work with `Date` class.
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, and later
Built-in.
Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android (<26), the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Format a Date String with Time zone and return Date object

I need to format a string date with given time zone and return the date object back. I am currently in IST time zone.
So IST is 5 hours and 30 minutes ahead of UTC.
public void getDate(){
String dateStr = "11/25/2016T13:30:00.000";
String dateFormat = "MM/dd/yyyy'T'HH:mm:ss.SSS";
Date date = formatedStringToDate(dateStr, dateFormat);
System.out.println(date);
}
public static Date formatedStringToDate(final String date, final String dateFormat) throws ParseException {
final SimpleDateFormat sdf = new SimpleDateFormat(dateFormat);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
Date parsedDate = null;
if (date != null) {
try {
parsedDate = sdf.parse(date);
} catch (ParseException e) {
throw e;
}
}
return parsedDate;
}
I get the below out put.
Fri Nov 25 19:00:00 **IST** 2016
The time seems to be change from 5.30 hours but then if its a IST to UCT time converstion, it should be 5.30 hours before 13:30:00 which is 08:00:00?
Also how could I change the highlighted IST part of out put string to show the currect time zone in this case UTC?

When you call toString on a Date (by printing it) you get the default format (because a Date is an object that stores a number of milliseconds, or nanoseconds in Java 9+, since an epoch). To see the result in UTC you need something like,
final DateFormat sdf = DateFormat.getDateTimeInstance(DateFormat.FULL,
DateFormat.FULL);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
Date date = formatedStringToDate(dateStr, dateFormat);
System.out.println(sdf.format(date)); // <-- format the Date

tl;dr
LocalDateTime.parse( "2017-11-25T13:30:00.000" )
.atZone( ZoneId.of( "Asia/Kolkata" ) )
2017-11-25T13:30+05:30[Asia/Kolkata]
java.time
The modern approach uses the java.time classes that replaced the troublesome old legacy date-time classes.
Parse your input string as a LocalDateTime given the lack of any indicator of zone or offset-from-UTC.
Using standard ISO 8601 format for such strings is preferred. The java.time classes use the standard formats by default when parsing/generating strings.
LocalDateTime ldt = LocalDateTime.parse( "2017-11-25T13:30:00.000" ) ;
ldt.toString(): 2017-11-25T13:30
If you are certain this date-time was intended to represent a moment by the wall-clock time of India, then assign a time zone to produce a ZonedDateTime object.
Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).
ZoneId z = ZoneId.of( "Asia/Kolkata" ) ;
ZonedDateTime zdt = ldt.atZone( z ) ;
zdt.toString(): 2017-11-25T13:30+05:30[Asia/Kolkata]
You can adjust into another zone for comparison.
ZonedDateTime zdtMontreal = zdt.withZoneSameInstant( ZoneId.of( "America/Montreal") );
zdtMontreal.toString(): 2017-11-25T03:00-05:00[America/Montreal]
To parse/generate strings in other formats such as the one in your Question, use the DateTimeFormatter or DateTimeFormatterBuilder classes. Search Stack Overflow for more info, as these have been covered extensively.
DateTimeFormatter f = DateTimeFormatter.ofPattern( "MM/dd/uuuu'T'HH:mm:ss.SSS" , Locale.US ) ;
Use that formatter for parsing.
LocalDateTime ldt = LocalDateTime.parse( "11/25/2016T13:30:00.000" , f ) ;
And for generating.
String output = ldt.format( f ) ; // Generate string.
Consider using ISO 8601 formats instead.
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
With a JDBC driver complying with JDBC 4.2 or later, you may exchange java.time objects directly with your database. No need for strings or java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, and later
Built-in.
Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and Java SE 7
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
Later versions of Android bundle implementations of the java.time classes.
For earlier Android, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above). See How to use ThreeTenABP….
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

Java, How to change GMT time to local time?

Server sends me time like this:
2012-06-08 17:00:00 +0100
I need to change it like HH:MM based on local time. For example this time is what time at Japan, India, US and etc.
How can I do this? Thanks

Option 1: using java.util.Date/Calendar:
First you need to parse the value to a Date, then reformat it in the format and time zone
you're interested in:
SimpleDateFormat inputFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z",
Locale.US);
Date date = inputFormat.parse(inputText);
// Potentially use the default locale. This will use the local time zone already.
SimpleDateFormat outputFormat = new SimpleDateFormat("HH:mm", Locale.US);
String outputText = outputFormat.format(date);
Option 2: using Joda Time
Joda Time is a much better date/time library for Java.
DateTimeFormatter inputFormatter = DateTimeFormat
.forPattern("yyyy-MM-dd HH:mm:ss Z")
.withLocale(Locale.US);
DateTime parsed = inputFormatter.parseDateTime(inputText);
DateTimeFormatter outputFormatter = DateTimeFormat
.forPattern("HH:mm")
.withLocale(Locale.US)
.withZone(DateTimeZone.getDefault());
String outputText = outputFormatter.print(parsed);
Note that you should only convert to/from string representations when you really need to. Otherwise, use the most appropriate type based on your usage - this is where Joda Time really shines.

Use JodaTime. It's far better and safer than Java's Date and Time API. There are a lot of methods that return a LocalTime object (HH:MM).
As an example, new DateTime(your date time).toLocalTime();

java.util.Date is always in UTC. What makes you think it's in local time? I suspect the problem is that you're displaying it via an instance of Calendar which uses the local timezone, or possibly using Date.toString() which also uses the local timezone.
If this isn't the problem, please post some sample code.
I would, however, recommend that you use Joda Time anyway, which offers a much clearer API.

The other Answers are correct but outdated. Use java.time classes instead.
tl;dr
ZonedDateTime zdt_Kolkata = OffsetDateTime.parse( "2012-06-08 17:00:00 +0100" , DateTimeFormatter.ofPattern( "yyyy-MM-dd HH:mm:ss Z" ) ).atZone( ZoneId.of( "Asia/Kolkata" ) );
Using java.time
Define a DateTimeFormatter formatting pattern to match your input String.
String input = "2012-06-08 17:00:00 +0100";
DateTimeFormatter f = DateTimeFormatter.ofPattern( "yyyy-MM-dd HH:mm:ss Z" );
OffsetDateTime
Parse the String as an OffsetDateTime object that represents the +0100 in your input which means “one hour ahead of UTC”.
OffsetDateTime odt = OffsetDateTime.parse( input , f );
ZonedDateTime
Apply a ZoneId to produce a ZonedDateTime for any desired time zone. Specify a proper time zone name. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).
ZoneId zoneId_Kolkata = ZoneId.of( "Asia/Kolkata" ); // India
ZonedDateTime zdt_Kolkata = odt.atZone( zoneId_Kolkata );
…and another…
ZoneId zoneId_Montréal = ZoneId.of( "Asia/Montreal" ); // Québec Canada
ZonedDateTime zdt_Montréal = odt.atZone( zoneId_Montréal );
Instant
For UTC, extract an Instant object. The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds.
Instant instant = zdt_Montréal.toInstant();
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the old troublesome date-time classes such as java.util.Date, .Calendar, & java.text.SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to java.time.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations.
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP.
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time.

Inconsistent date parsing using SimpleDateFormat

I'm really scratching my head on this one. I've been using SimpleDateFormats with no troubles for a while, but now, using a SimpleDateFormat to parse dates is (only sometimes) just plain wrong.
Specifically:
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
Date date = sdf.parse("2009-08-19 12:00:00");
System.out.print(date.toString());
prints the string Wed Aug 19 00:00:00 EDT 2009. What the heck? - it doesn't even parse into the wrong date all the time!
Update: That fixed it beautifully. Wouldn't you know it, that was misused in a few other places as well. Gotta love debugging other people's code :)

I think you want to use the HH format, rather than 'hh' so that you are using hours between 00-23. 'hh' takes the format in 12 hour increments, and so it assumes it is in the AM.
So this
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = sdf.parse("2009-08-19 12:00:00");
System.out.print(date.toString());
Should print out
Wed Aug 19 12:00:00 EDT 2009

The hour should be specified as HH instead of hh. Check out the section on Date and Time patterns in http://java.sun.com/javase/6/docs/api/java/text/SimpleDateFormat.html

You're printing out the toString() representation of the date, rather than the format's representation. You may also want to check the hour representation. H and h mean something different. H is for the 24 hour clock (0-23), h is for the 12 hour clock (1-12), (there is also k and K for 1-24 and 0-11 based times respectively)
You need to do something like:
//in reality obtain the date from elsewhere, e.g. new Date()
Date date = sdf.parse("2009-08-19 12:00:00");
//this format uses 12 hours for time
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
//this format uses 24 hours for time
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
System.out.print(sdf.format(date));
System.out.print(sdf2.format(date));

tl;dr
LocalDateTime ldt = LocalDateTime.parse( "2009-08-19 12:00:00".replace( " " , "T" ) );
java.time
Other Answers are correct but use legacy date-time classes. Those troublesome old classes have been supplanted by the java.time classes.
Your input string is close to standard ISO 8601 format. Tweak by replacing the SPACE in the middle with a T. Then it can be parsed without specifying a formatting pattern. The java.time classes use ISO 8601 by default when parsing/generating Strings.
String input = "2009-08-19 12:00:00".replace( " " , "T" );
The input data has no info about offset-from-UTC or time zone. So we parse as a LocalDateTime.
LocalDateTime ldt = LocalDateTime.parse( input );
If by the context you know the intended offset, apply it. Perhaps it was intended for UTC (an offset of zero), where we can use the constant ZoneOffset.UTC.
OffsetDateTime odt = ldt.atOffset( ZoneOffset.UTC );
Or perhaps you know it was intended for a particular time zone. A time zone is an offset plus a set of rules for handling anomalies such as Daylight Saving Time (DST).
ZonedDateTime zdt = ldt.atZone( ZoneId.of( "America/Montreal" ) );
About java.time
The java.time framework is built into Java 8 and later. These classes supplant the old troublesome date-time classes such as java.util.Date, .Calendar, & java.text.SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to java.time.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations.
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport and further adapted to Android in ThreeTenABP (see How to use…).
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time.