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how to convert LocalDate to a specific date time format [closed]

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how to convert ISO_LOCAL_DATE to date time format : yyyy-MM-dd'T'HH:mm:ss.SSSZ in java
Ex: given date: 2016-01-25 to 2016-01-25T00:00:00.000+0100

I am assuming that have got a string, for example 2016-01-25, and that you want a string containing the start of the day in the JVM’s default time zone (it wasn’t clear from the question). I first define a formatter for the format that you want (it’s ISO 8601):
private static DateTimeFormatter formatter
= DateTimeFormatter.ofPattern("uuuu-MM-dd'T'HH:mm:ss.SSSxx");
Now your conversion goes:
String isoLocalDateString = "2016-01-25";
LocalDate date = LocalDate.parse(isoLocalDateString);
ZonedDateTime dateTime = date.atStartOfDay(ZoneId.systemDefault());
String dateTimeString = dateTime.format(formatter);
System.out.println(dateTimeString);
When running in my time zone, Europe/Copenhagen, output from this example code is what you asked for:
2016-01-25T00:00:00.000+0100
In rare cases where summer time (DST) begins at the first moment of the day, the time of day will not be 00:00:00.000.
For parsing with ISO_LOCAL_DATE we don’t need to specify the formatter since this formatter is the default for LocalDate.parse().
All of this said, you should not normally want to convert a date from one string format to another string format. Inside your program keep dates as LocalDate objects. When you get string input, parse into a LocalDate. Only when you need to give string output, for example in data exchange with another system, format into a string in the required format.
Link: Wikipedia article: ISO 8601

There are various methods on LocalDate for this, including:
LocalDate::toDateTimeAtCurrentTime()
LocalDate::toDateTimeAtStartOfDay()
LocalDate::toDateTime( LocalTime )
LocalDate::toDateTime( LocalTime , DateTimeZone )

It is as simple as LocalDateTime localDateTime = yourLocalDate.atStartOfDay()
Update
Adding timestamp is as simple as:
ZoneId zoneId = ZoneId.of("America/New_York");
ZonedDateTime = zdt = localDateTime.atZone(zoneId);
Can be put together as
ZonedDateTime zdt = yourLocalDate.atStartOfDay().atZone(ZoneId.of("America/New_York"));

Translating from a String to a Timestamp and back [closed]

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I work with the date in my API on Java. I want to get today's date and time, write it to a class and then to a csv file (I use a csv file as a data store). Then, to implement the function of getting a report on records for today, to get it and to compare it with today's date (exactly the date, without time). What is the best way to do this? Right now I'm storing this in Timestamp, but it doesn't seem to be correct and should I use String? Then I need two parsers? To translate from a string to a date and time and from that to just a DATE? Which library is better to use for this?
I wrote a translation from a string to a timestamp, is this correct?
default Timestamp StringToTimestamp(String date) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-YYYY");
Date parsedDate = null;
try {
parsedDate = dateFormat.parse(date);
} catch (ParseException e) {
e.printStackTrace();
log.error("Error in date parsing");
}
return new Timestamp(parsedDate.getTime());
}
UPD
I changed my code for the java.time library, but it seems I did something wrong
default LocalDate StringToTimestamp(String date) {
DateTimeFormatter dtf = DateTimeFormatter.ofPattern('yyyy-mm-dd');
LocalDate date = LocalDate.parse(date, dtf);
return date;
}
UPD I edited the code according to the answer #OleV.V. It works really cool

java.time
I recommend that you use java.time, the modern Java date and time API, for your date and time work. I suggest writing the current date and time with offset from UTC to the CSV file.
OffsetDateTime dateTime = OffsetDateTime.now(ZoneId.systemDefault());
String stringForCsvFile = dateTime.toString();
System.out.println(stringForCsvFile);
Output when running in my time zone just now:
2020-12-26T11:02:07.368973+01:00
The string is in ISO 8601 format, which should be the best to avoid surprises for anyone reading it. The classes of java.time generally print ISO 8601 format from their toString methods.
Often you will value consistency higher than knowing which UTC offset was used when writing the file. If so, write the time in UTC to the file:
Instant now = Instant.now();
String stringForCsvFile = now.toString();
2020-12-26T10:02:07.373439Z
No matter which way you used above, after reading the timestamp from the file, convert like this:
ZoneId zone = ZoneId.systemDefault();
String stringFromCsvFile = "2020-12-26T11:02:07.368973+01:00";
ZonedDateTime dateTime = OffsetDateTime.parse(stringFromCsvFile)
.atZoneSameInstant(zone);
LocalDate dateFromCsv = dateTime.toLocalDate();
LocalDate today = LocalDate.now(zone);
System.out.println("Same day? " + dateFromCsv.isEqual(today));
Same day? true
I have made sure that both dates I compare are in the time zone of the JVM where the program is running. Please consider whether there’s a specific time zone you want, and if so, set zone to something like ZoneId.of("Asia/Baku"). It matters: it is never the same date in all time zones.
If you want to know whether the date is earlier or later, use the isBefore or isAfter method of LocalDate.
Was your code correct?
IMHO the worst problem with your code is using the old and poorly designed date-time classes: SimpleDateFormat, Date and Timestamp. SimpleDateFormat is a notorious troublemaker of a class. Date had severe design flaws in Java 1.0, therefore most constructors and methods were deprecated already in Java 1.1. Timestamp was never meant for other purposes than transferring high-precision timestamps to and from SQL databases (which we also don’t use it for anymore). And it’s a true hack on top of the already poorly designed Date class. I furthermore see nothing that you will want to use the high precision of Timestamp for, so using it here seems pointless.
There is a bug in your code: You are using upper case YYYY in your format pattern. This is for week year and only useful with a week number. I tried giving 24-06-2021 to your method. It returned 2021-01-04 00:00:00.0. It’s 5 months 20 days off because of the mentioned error. Apparently SimpleDateFormat defaulted to the start of week 1 in the week year and ignored the month and day of month.
As an aside, had you tried parsing with the same format pattern string with java.time, it would at least have told you that this was wrong.
Links
Oracle tutorial: Date Time explaining how to use java.time.
Wikipedia article: ISO 8601
Related question: java parsing string to date

Java LocalDateTime pattern [closed]

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I used DateTimeFormatter.ofPattern('yyyy-MM-dd'T'HH:mm:ssZ')
and I get error like this
java.time.format.DateTimeParseException: Text '2020-04-13T12:05:54+0600' could not be parsed at index 19
String which i wanna parse is '2020-04-13T12:05:54+0600'
so how can i solve this? What pattern i need to use?

Your code is using LocalDate which only parses a date - not a date and time so you are getting an error when the parse finds the space after the date.
So you should be using LocalDateTime but LocalDateTime.parse(String) expects an ISO format date which is not the format you are using.
So you need to use a DateTimeFormatter to specify the format of your input string. Something like:
DateTimeFormatter format = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSX");
LocalDateTime result = LocalDateTime.parse(convertDate, format);
Answer copied from greg449’s answer here

You can pass pattern of Like this way.
DateTimeFormatter.ofPattern("yyyy MM dd");
Please follow the documentation to pass proper pattern.
https://docs.oracle.com/javase/8/docs/api/java/time/format/DateTimeFormatter.html

2017-01-01 00:08:57.231 format equals yyyy-MM-dd.HH:mm:ss? [closed]

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I'm a bit baffled what format these timestamps are in. I was told the format to use is yyyy-MM-dd.HH:mm:ss but all of the timestamps appear like this 2017-01-01 00:08:57.231, 2017-01-01 07:43:36.348, or 2017-01-01 13:25:55.683. I'm not understanding why there are four sections to the time ?:Hour:Minute:Second in the actual data I have when the format I'm supposed to be using only has three time sections. Are these datetime timestamps not actually in the format of yyyy-MM-dd.HH:mm:ss?

No, your suspicion is correct, your example date-time strings are not in the format yyyy-MM-dd.HH:mm:ss. The dot between dd and HH must be a simple mistake, it should be a space since there is a space between date and time in the timestamp strings. Furthermore all of your example strings include milliseconds: in 00:08:57.231 you’ve got 57 seconds and 231 milliseconds, or if you like, 57.231 seconds, so the last section may also be referred to as fraction of second.
DateTimeFormatter formatter
= DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss.SSS");
String timestampString = "2017-01-01 00:08:57.231";
LocalDateTime dateTime = LocalDateTime.parse(timestampString, formatter);
System.out.println(dateTime);
Output:
2017-01-01T00:08:57.231
For the nerdily curious: It is possible to parse the string, or more precisely most of it, with the format you had been given, only correcting the dot into a space:
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String timestampString = "2017-01-01 00:08:57.231";
LocalDateTime dateTime = LocalDateTime.from(
formatter.parse(timestampString, new ParsePosition(0)));
In this case the result comes without the milliseconds:
2017-01-01T00:08:57
I see no reason why you should want this, though.
Avoid SimpleDateFormat
In a comment you gave a snippet that uses the SimpleDateFormat class. This class is not only long outdated, it is also notoriously troublesome. I see no reason why you should want to use it. Instead I am using java.time, the modern Java date and time API. In my experience it is so much nicer to work with.
Links
Oracle tutorial: Date Time explaining how to use java.time. You may especially want to study the section Parsing and Formatting.

These time stamps are in yyyy-MM-dd HH:mm:ss:ms format, last three digits are milliseconds.

How to convert Object as timestamp to formatted date [closed]

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How to convert Object as timestamp to formatted date?
I have printed out timestamp(
1395500668
) that is in Object.
I want to format this and print it out like
yyyy-MM-dd H:m:s

Assuming you have a string that represents epoch time in seconds (as you have not told us what your Object actually is), first convert it to a long:
long epoch = Long.parseLong("1395500668");
You'll then need to convert it to milliseconds:
epoch *= 1000;
Then you can convert it to a java.util.Date using the Date constructor that takes millisecond epoch time:
Date date = new Date(epoch);
And finally you can format that Date as a string using standard formatting techniques.

First convert the timestamp value into Date and then format the date into your desired format using SimpleDateFormat
java.util.Date date = new java.util.Date(new Long(1395500668) * 1000);
String dateStr = new java.text.SimpleDateFormat("yyyy-MM-dd H:m:s").format(date);
System.out.println(dateStr);
It outputs:
2014-03-22 8:4:28

Convert it first into a Date first by casting the Object into a Timestamp and then using the getTime() method as shown in How to convert TimeStamp to Date in Java?
Then use a SimpleDateFormat to format the date as needed as shown in Change date format in a Java string