I need to parse a date string with timezone to Date object. The input date string pattern is:
"MM/dd/yyyy hh:mm a z" (eg: 04/30/2018 06:00 PM IST).
I have used below given code. But it returns incorrect date as output.
new SimpleDateFormat("MM/dd/yyyy hh:mm a z").parse("04/30/2018 06:00 PM IST")
Current Output: "Mon Apr 30 09:00:00 PDT 2018".
Expected Output: "Mon Apr 30 05:30:00 PDT 2018.
That's because timezone's abbreviations such as IST are ambiguous. IST is used in India, Israel and Ireland, and SimpleDateFormat assumes some of them as default, in obscure and undocumented ways (AFAIK). Actually, according to javadoc: "support of abbreviations is for JDK 1.1.x compatibility only and full names should be used".
One way to make it work is to arbitrarily choose a timezone and set it in the formatter:
SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy hh:mm a z");
sdf.setTimeZone(TimeZone.getTimeZone("Asia/Kolkata"));
Date date = sdf.parse("04/30/2018 06:00 PM IST");
Always use names in the format Continent/Region, such as Asia/Kolkata. Those names are IANA's timezones names, and they are not ambiguous, so this make things work.
java.time API
If you're using Java 8 or higher, switch to the java.time API, which is much better. For Java 7 or lower, there's the Threeten Backport with the same classes and functionality.
In this API, you must set a list of all preferred timezones to be used in case of ambiguous names like IST:
// prefered zones
Set<ZoneId> preferredZones = new HashSet<>();
preferredZones.add(ZoneId.of("Asia/Kolkata"));
DateTimeFormatter fmt = new DateTimeFormatterBuilder()
// date and time
.appendPattern("MM/dd/yyyy hh:mm a ")
// zone (use set of prefered zones)
.appendZoneText(TextStyle.SHORT, preferredZones)
// use English, because different locales can affect timezones names
.toFormatter(Locale.ENGLISH);
ZonedDateTime zdt = ZonedDateTime.parse("04/30/2018 06:00 PM IST", fmt);
If you still need to use java.util.Date, it's easy to convert:
// Java 8
Date d = Date.from(zdt.toInstant());
// Java 7 (Threenten Backport)
Date d = DateTimeUtils.toDate(zdt.toInstant());
The resultant Date object will not hold any timezone information. See the similar query in this stackoverflow thread
You might be getting the correct date but in your JVM's current timezone.
In case if you are using Java 8, then there's a provision of Date object with timezone. Look at ZonedDateTime, but for this you need a different kind of formatter while parsing (DateTimeFormatter)
Related
I want to convert the date in string to date object being the string "10h 57m 20s October 13 2020". How can be done? may replace firstly the h, m and s to get the format "10:57:20 October 13 2020"? As well, I tried the last format "10:57:20 October 13 2020" to get the date with DateTimeFormat and DateTimeFormatterBuilder() but is does not work with the month or it works but the hour coverts to 00:00:00.
Thanks
java.time
I recommend that you use java.time, the modern Java date and time API, for your date and time work. Like Joop Eggen already wrote, put the letters that are part of your format in single quotes in the format pattern string:
private static final DateTimeFormatter FORMATTER
= DateTimeFormatter.ofPattern("H'h' m'm' s's' MMMM d y", Locale.ENGLISH);
This will allow you to parse like this:
String dateInString = "10h 57m 20s October 13 2020";
LocalDateTime dateTime = LocalDateTime.parse(dateInString, FORMATTER);
System.out.println(dateTime);
Output:
2020-10-13T10:57:20
You shouldn’t take any interest in the old-fashioned Date class. However, sometimes we need to pass a Date to a legacy API not yet upgraded to java.time. The conversion requires that we know the time zone assumed for the parsed date and time. For example:
ZoneId zone = ZoneId.of("America/Tegucigalpa");
Instant i = dateTime.atZone(zone).toInstant();
Date oldfashionedDate = Date.from(i);
System.out.println(oldfashionedDate);
Example output:
Tue Oct 13 10:57:20 CST 2020
Tutorial link
Oracle tutorial: Date Time explaining how to use java.time.
You can place fixed letters in apostrophes.
"HH'h' mm'm' ss's' MMMM dd yyyy"
Furthermore hh is the 12 hour format to be combined wiht a AM/PM.
HH is the 24 hour format.
Also the locale must be correct, maybe explicitly set. Here English.
I am trying to convert an Instant to a String with the format like "10 Jul 2021, 10:00 PM".
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd LLL yyyy, hh:mm a");
String formattedDate = formatter.withZone(ZoneId.from(ZoneOffset.UTC)).format(instant);
It works as expected on my machine, but it comes out as "10 7 2021, 10:00 PM" in other environments.
Use MMM for month abbreviation and specify desired locale
Instant instant = Instant.ofEpochSecond(1_625_954_400);
DateTimeFormatter formatter
= DateTimeFormatter.ofPattern("dd MMM uuuu, hh:mm a", Locale.US);
String formattedDate = formatter.withZone(ZoneOffset.UTC).format(instant);
System.out.println(formattedDate);
Output:
10 Jul 2021, 10:00 PM
This should be stable across computers except that it may theoretically vary with different Java versions. I don’t expect it to.
What went wrong in your code?
By all likelihood the inconsistent results that you have observed are due to different locales. When not instructed otherwise, the one-arg DateTimeFormatter.ofPattern() gives you a formatter that is using the default locale of the JVM (usually taking from an operating system setting). This will give you very varied results on computers and JVMs with different language and region settings. To confuse things further locale data vary with Java version and locale provider setting (the java.locale.providers system property). On my Java 8 very many locales gave 7 as month from LLL and only German have Jul. On my Java 11 only the Vai language of Liberia gives 7 while many give Jul.
Format pattern letter L is for the stand-alone form of month name or abbreviation and should generally not be used when the month is part of a date as it is in your case. In most locales L and M give the same results, but there are locales where there’s a difference and on purpose.
Try this code: this will work 100%
DateFormat df = new SimpleDateFormat("dd-MMMM-yyyy HH:mm a");
Date date = new Date(System.currentTimeMillis());
String infi = df.format(date);
And the output be like
18-May-2021 11:31 PM
I have a timestamp 2018-01-01 18:20:23.11 which is in UTC. I need to print this in a different format but retain the UTC timezone. However if I use SimpleDateFormat ("dd MMM YYYY yyyy kk:mm z"), it takes my current timezone and gives me 01 Jan 2018 18:20 EST. I want this to print 01 Jan 2018 18:20 UTC. Doing a Timezone.getTimeZone("UTC") converts this time to UTC (does a +4 to hours)which is not the desired result.
DateTimeFormatter originalFormatter
= DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss.SS");
DateTimeFormatter newFormatter
= DateTimeFormatter.ofPattern("dd MMM uuuu HH:mm z", Locale.ENGLISH);
String originalTimestamp = "2018-01-01 18:20:23.11";
String differentFormat = LocalDateTime.parse(originalTimestamp, originalFormatter)
.atZone(ZoneId.of("Etc/UTC"))
.format(newFormatter);
System.out.println(differentFormat);
This prints
01 Jan 2018 18:20 UTC
ZoneId.of("Etc/UTC") or ZoneOffset.UTC?
A possibly nerdy edit: I had first written .atZone(ZoneOffset.UTC) in the conversion. I usually use ZoneOffset.UTC to denote UTC and consider this the nice and idiomatic way of specifying it. However in the case of your code, this resulted in the zone being given as Z in the output where you had asked for UTC. Using ZoneId.of("Etc/UTC") instead gives you what you want. I can find no other way of making sure that the zone is formatted as UTC (save hardcoding UTC in the format pattern string, but that would be an ugly hack).
BTW ZoneId.of("Etc/UTC").normalized() returns ZoneOffset.UTC (at least on my Java 10, but I expect it to be the case always).
SimpleDateFormat vs. java.time
SimpleDateFormat is not only long outdated, it is also notoriously troublesome. I recommend you avoid it. It is correct, as you have observed, that it uses your JVM’s default time zone. There is a way to persuade it to do differently, but I would not bother.
java.time is the modern Java date and time API. It came out in 2014 as a replacement for the old and poorly designed date and time classes. IMHO it is so much nicer to work with.
Link: Oracle tutorial: Date Time explaining how to use java.time
I read many posts at SO and tested most of them. None of them is working for me. Here is my code:
DateTimeZone fromTimeZone = DateTimeZone.forID("America/New_York");
DateTimeZone toTimeZone = DateTimeZone.forID("US/Central");
Date now = new Date();
DateTime dateTime = new DateTime(now, fromTimeZone);
DateTime newDateTime = dateTime.withZone(toTimeZone);
System.out.println(dateTime.toDate() + "--" + newDateTime.toDate());
Here is what I got in print:
Tue Aug 22 13:08:13 EDT 2017--Tue Aug 22 13:08:13 EDT 2017
I am hoping to display "Tue Aug 22 12:08:13 CDT 2017" for the second time zone.
A java.util.Date doesn't have timezone information. Joda's DateTime has, but it's wrapped into a Chronology to translate this instant to "human readable" date/time fields.
But in the end, both objects just represent points (instants) in the time-line.
Just check the values of dateTime.getMillis(), newDateTime.getMillis(), dateTime.toDate().getTime() and newDateTime.toDate().getTime(). They will all be exactly the same, and this value represents the number of milliseconds since epoch (1970-01-01T00:00Z).
The timezone passed to the DateTime object just affects the output of toString() (when this milliseconds value is "translated" to a local date and time), but it doesn't change the milliseconds value itself. So if you do:
DateTime dateTime = new DateTime(now, fromTimeZone);
System.out.println(dateTime);
It will print the date and time that's equivalent to the milliseconds value, but converted to the fromTimeZone (America/New_York):
2017-08-22T13:33:08.345-04:00
The withZone method just sets to a different timezone, but keeps the same milliseconds value:
DateTime newDateTime = dateTime.withZone(toTimeZone);
System.out.println(newDateTime);
The code above keeps the instant (the milliseconds value), but prints the equivalent date and time in the toTimeZone (US/Central):
2017-08-22T12:33:08.345-05:00
The .toDate() method returns a java.util.Date, which just contains the same milliseconds value, and no timezone information. Then, System.out.println implicity calls Date::toString() method, and this converts the milliseconds value to the JVM's default timezone. In this case both will be:
Tue Aug 22 13:33:08 EDT 2017
Because both dates represent the same instant (the same number of milliseconds since epoch).
If you want to get a String that contains the date in a specific format, you can use a org.joda.time.format.DateTimeFormatter:
DateTimeFormatter fmt = DateTimeFormat.forPattern("EEE MMM dd HH:mm:ss z yyyy").withLocale(Locale.ENGLISH);
System.out.println(fmt.print(new DateTime(DateTimeZone.forID("US/Central"))));
There's no need to convert dates objects, because actually no conversion is really happening: all methods above don't change the milliseconds value.
Also note that I used a java.util.Locale to make sure the month and day of week are in English. If you don't specify a locale, the JVM default will be used, and it's not guaranteed to always be English (and it can also be changed, even at runtime, so it's better to always specify it).
Then I get the current date and set the timezone to be used when printing it. Note that you can get a DateTime directly, there's no need to create a java.util.Date.
The output will be:
Tue Aug 22 12:33:08 CDT 2017
To get exactly the same output you want (with both dates), you can do:
DateTimeFormatter fmt = DateTimeFormat.forPattern("EEE MMM dd HH:mm:ss z yyyy").withLocale(Locale.ENGLISH);
DateTime nowNy = new DateTime(DateTimeZone.forID("America/New_York"));
DateTime nowCentral = nowNy.withZone(DateTimeZone.forID("US/Central"));
System.out.println(fmt.print(nowNy) + "--" + fmt.print(nowCentral));
The output will be:
Tue Aug 22 13:33:08 EDT 2017--Tue Aug 22 12:33:08 CDT 2017
Java new Date/Time API
Joda-Time is in maintainance mode and being replaced by the new APIs, so I don't recommend start a new project with it. Even in joda's website it says: "Note that Joda-Time is considered to be a largely “finished” project. No major enhancements are planned. If using Java SE 8, please migrate to java.time (JSR-310)." (if you don't want to or can't migrate from Joda to another API, you can desconsider this section).
If you're using Java 8, consider using the new java.time API. It's easier, less bugged and less error-prone than the old APIs.
If you're using Java <= 7, you can use the ThreeTen Backport, a great backport for Java 8's new date/time classes. And for Android, there's the ThreeTenABP (more on how to use it here).
The code below works for both.
The only difference is the package names (in Java 8 is java.time and in ThreeTen Backport (or Android's ThreeTenABP) is org.threeten.bp), but the classes and methods names are the same.
The relevant classes are DateTimeFormatter (to format the date to a String in a specific format), ZonedDateTime (which represents a date and time in a specific timezone) and a ZoneId (which represents a timezone):
// formatter - use English locale for month and day of week
DateTimeFormatter fmt = DateTimeFormatter.ofPattern("EEE MMM dd HH:mm:ss z yyyy", Locale.ENGLISH);
// current date/time in New York timezone
ZonedDateTime nowNy = ZonedDateTime.now(ZoneId.of("America/New_York"));
// convert to another timezone (US/Central)
ZonedDateTime nowCentral = nowNy.withZoneSameInstant(ZoneId.of("US/Central"));
// format dates
System.out.println(fmt.format(nowNy) + "--" + fmt.format(nowCentral));
The output is the same as above.
I've been trying to convert the time since epoch until today and display it in Eastern Standard Time. Here is what outputs on the remote machine (it's remotely hosted):
Date now = new Date(System.currentTimeMillis());
System.out.println(now.toString());
// Thu Apr 24 14:36:11 MST 2014
No idea what MST is, but I want to get the current milliseconds since epoch in EST, and display the result in EST.
No matter what I do, I can't get daylights savings to work (it's currently Daylights Savings Time in the EST Time Zone); I either end up in PST, GMT or UTC, and when I do get "EST" it's either some random value or 1 hour behind or 3 hours behind.
I would like the output to be formatted using this DateFormat:
DateFormat EXPIRE_FORMAT = new SimpleDateFormat("MMM dd, yyyy h:mm a z");
Just set the time zone you want the time to be displayed in using DateFormat#setTimeZone(TimeZone)
Date now = new Date(System.currentTimeMillis());
DateFormat EXPIRE_FORMAT = new SimpleDateFormat("MMM dd, yyyy h:mm a z");
EXPIRE_FORMAT.setTimeZone(TimeZone.getTimeZone("America/Montreal")); // or whatever relevant TimeZone id
System.out.println(EXPIRE_FORMAT.format(now));
AFAIK, there is no EST currently. It's all EDT in Spring.
The above prints
Apr 24, 2014 5:53 PM EDT
The comments and the answer by Sotirios Delimanolis are correct.
Avoid 3 or 4 Letter Time Zone Codes
You should avoid the 3 or 4 letter codes for time zones as they are neither standardized nor unique. Instead use proper time zone names, usually a continent+city.
Avoid j.u.Date
The java.util.Date and .Calendar & SimpleDateFormat classes bundled with Java are notoriously troublesome. Use a decent date-time library with an updated time zone database. For Java, that means either Joda-Time or the new java.time package in Java 8 (inspired by Joda-Time).
Avoid Milliseconds-Since-Epoch
I suggest you avoid working with milliseconds since epoch. Gets confusing fast as the number is meaningless when read by a human. Let the date-time library manage the milliseconds for you.
Specify Time Zone
Generally best to specify the desired/intended time zone. If you omit the time zone, all the major date-time libraries (java.util.Date, Joda-Time, java.time) apply the JVM's default time zone.
Joda-Time Example
Example code in Joda-Time 2.3.
DateTimeZone timeZoneToronto = DateTimeZone.forID( "America/Toronto" );
DateTime dateTimeToronto = new DateTime( timeZoneToronto ); // Current moment.
DateTime dateTimeUTC = dateTimeToronto.withZone( DateTimeZone.UTC );
DateTime dateTimeParis = dateTimeToronto.withZone( DateTimeZone.forID( "Europe/Paris" ) );
If you really want the milliseconds since epoch, call the getMillis method. In example code above, all three DateTime objects have the same number of milliseconds-since-epoch.
long millis = dateTimeToronto.getMillis();
If you need a java.util.Date for use with other classes…
java.util.Date date = dateTimeToronto.toDate();
While Joda-Time uses the ISO 8601 standard formats as its defaults, you may specify other formats for generating strings.
DateTimeFormatter formatter = DateTimeFormat.forPattern( "MMM dd, yyyy h:mm a z" );
String output = formatter.print( dateTimeToronto );