just a question what i am doing wrong. I have this code:
public static int berechneSekundenwert(String datum, String zeit) throws ParseException {
Date dt = new Date();
SimpleDateFormat df = new SimpleDateFormat( "dd.MM.yyyy HH:mm:ss" );
dt = df.parse( datum+" "+ zeit);
int gesamtzeit = (int)dt.getTime();
return gesamtzeit;
}
Now my import format is:
09.11.2019 01:30:17
What i want to do is calculate the time passed for these dates, so i
can later sort them by time. But i get negative values?!
Example output (passed time, date, daytime):
-2120215336 30.09.2019 12:03:35
1757321960 25.09.2019 16:06:25
-2111322336 30.09.2019 14:31:48
-1281127040 21.08.2019 12:05:36
-1280681040 21.08.2019 12:13:02
377782960 09.09.2019 16:54:06
1301386664 09.11.2019 01:30:17
710621960 13.09.2019 13:21:25
712564960 13.09.2019 13:53:48
Shouldn't they all be positive, since java states, that the getTime function measures the time since 01.01.1970
Anyone knows what i did wrong?
Computers use something called a timestamp to represent dates. In Java, Date::getTime() returns the milliseconds passed since 1970-01-01T00:00:00.000Z up to the date in question as long (64-bit integer).
In the code presented, this value is narrowed down to an int (32-bit integer). By narrowing the long to an int, the highest 32 bits get cut of. The largest value representable by an int is 2^31 - 1. A quick calculation shows that:
(2^31 - 1) (milliseconds)
/ 1000 (milliseconds per second)
/ 60 (seconds per minute)#
/ 60 (minutes per hour)
/ 24 (hours per day)
= 24.8551348032 (days)
This means that after roughly 25 days, the int will overflow (as it is defined in the Two's compliment). Not to mention that a later point in time could have a lower value than an earlier point in time, thus the negative values.
To fix this issue1, I would suggest to define gesamtzeit as long.
Two remarks on your code:
java.util.Date is regarded as outdated. I would suggest to use java.time.Instant instead.
I would suggest to use English in the source code, only exception being you use domain-specific words that cannot (well) be translated to English.
1 This is only a temporary fix. All representation with a fixed number of bits will eventually overflow. In fact, all representation with any memory constraint at all will overflow eventually. I leave it up to the reader to find out when a 64-bit integer will overflow
tl;dr
See correct Answer by Turing85 about 32-bit versus 64-bit integers.
Use only modern java.time classes, never Date/SimpleDateFormat.
Consider the crucial issue of time zone or offset-from-UTC.
Educate the publisher of your data about the importance of (a) including zone/offset info, and (b) using ISO 8601 standard formats.
Code:
LocalDateTime.parse(
"09.11.2019 01:30:17" ,
DateTimeFormatter.ofPattern( "dd.MM.uuuu HH:mm:ss" )
)
.atOffset(
ZoneOffset.UTC
)
.toInstant()
.toEpochMilli()
See this code run live at IdeOne.com.
1573263017000
Details
The correct Answer by Turing85 addresses your specific question as to why the invalid negative numbers. But you have other problems.
ISO 8601
Now my import format is: 09.11.2019 01:30:17
I suggest you educate the publisher of this data about the ISO 8601 standard defining formats to use when communicating date-time values as text.
Legacy date-time classes
You are use terrible date-time classes that were supplanted years ago by the modern java.time classes defined in JSR 310. Never use Date or SimpleDateFormat.
Moment
Apparently you want to get a count of milliseconds since the epoch reference of first moment of 1970 in UTC. But doing that requires a moment, a specific point on the timeline.
Your input does not meet this requirement. Your input is a date and a time-of-day but lacks the context of an offset-from-UTC or a time zone.
So, take your example of 09.11.2019 01:30:17. We cannot know if this is 1:30 in the afternoon of Tokyo Japan, or 1:30 PM in Paris France, or 1:30 in Toledo Ohio US — which are all very different moments, several hours apart on the timeline.
So we must first parse your input as a LocalDateTime. This class represent a date and time without any concept of offset or zone.
String input = "09.11.2019 01:30:17" ;
DateTimeFormatter f = DateTimeFormatter.ofPattern( "dd.MM.uuuu HH:mm:ss" ) ;
LocalDateTime ldt = LocalDateTime.parse( input , f ) ;
Perhaps you know for certain the offset or zone intended by the publisher of this data. If so:
Suggest to the publisher of this data that they include the zone/offset info within their data.
Apply a ZoneOffset to get an OffsetDateTime, or a ZoneId to get a ZonedDateTime.
Perhaps you know for certain this input was intended for UTC, that is, an offset of zero hours-minutes-seconds.
OffsetDateTime odt = ldt.atOffset( ZoneOffset.UTC ) ;
To get a count of milliseconds since 1970-01-01T00:00Z convert to the basic building-block class Instant.
Instant instant = odt.toInstant() ;
Interrogate for a count of milliseconds since epoch.
long millisSinceEpoch = instant.toEpochMilli() ;
Understand that your original code ignored the crucial issue of time zone & offset-from-UTC. So your code implicitly applies the JVM's current default time zone. This means your results will vary at runtime, and means you likely have incorrect results too.
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.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
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.
why you downcast the return value ofgetTime()?
just make you method return long instead of int
and replace this line
int gesamtzeit = (int)dt.getTime();
with
long gesamtzeit = dt.getTime();
Related
This question already has answers here:
Android parsing String to Date time with SimpleDateFormat
(3 answers)
ParseException; must be caught (Try/Catch) (Java) [duplicate]
(1 answer)
Closed 2 years ago.
I have some dates in firebase and i need to retrieve as Miliseconds and do some operations with it.
the Date are like String in format "dd/MM/yyyy"
I tryed with a code like this, :
String myDate = "2014/10/29 18:10:45";
SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date = sdf.parse(myDate);
long millis = date.getTime();
My code, basically i tryed to get the storeged String from firebase and convert to a Date for compare with the current day and show the diference of days. the error that I have, is only in the word "parse" of my code
refresh.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String mydate = model.getParto();
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date date = sdf.parse(mydate);
}
});
but parse set an error
image of code and the string date in firebase
hope, someone can help
tl;dr
LocalDateTime
.parse(
"2014/10/29 18:10:45".replace( " " , "T" )
)
.atOffset( ZoneOffset.UTC )
.toInstant()
.toEpochMilli()
Need epoch reference
Representing a moment as a count of milliseconds requires a point in time as an epoch reference. You need to state the reference needed in your situation. I will assume the commonly used point of first moment of 1970 in UTC. But there are a couple dozen other points used by various systems. So you need to find out the meaning of your own data.
Need time zone or offset
Determining a moment requires more than a date and a time-of-day. You also need the context of a time zone or offset-from-UTC. Again, you need to specify this but did not. Is your example of ten minutes past six in the evening in Tokyo Japan, Toulouse France, or Toledo Ohio US? I will assume you mean an offset of zero hours-minutes-seconds. But again, you need to find out the meaning of your own data.
Avoid legacy date-time classes
Never use SimpleDateFormat, Date, or the other terrible date-time classes that were supplanted years ago by the modern java.time classes defined in JSR 310.
Date versus moment
Your Question in confused, referring to a date-only value as well as a date with time-of-day represented as milliseconds. These are two different kinds of data.
If representing a date-only, use LocalDate in Java and a type in your database akin to the SQL-standard DATE. I will ignore this date-only, and focus on tracking a moment.
Example code
Parse your input as LocalDateTime, after complying with standard ISO 8601 format by replacing SPACE in middle with a T.
A LocalDateTime does not represent a moment, is not a point on the timeline. You need to discover the zone/offset intended for you input, and apply. Apply the time zone intended for your input, to produce a ZonedDateTime. Or, if UTC (an offset of zero) was intended, apply a ZoneOffset to get an OffsetDateTime object. At this point we have determined a moment.
Extract a Instant object from the OffsetDateTime. Interrogate for a count of milliseconds since the epoch reference of 1970-01-01T00:00Z.
String myDate = "2014/10/29 18:10:45".replace( " " , "T" ) ; // Comply with ISO 8601 standard formatting.
LocalDateTime ldt = LocalDateTime.parse( input ) ;
OffsetDateTime odt = ldt.atOffset( ZoneOffset.UTC ) ; // Assuming your data was intended to represent a moment as seen in UTC, with an offset of zero hours-minutes-seconds.
Instant instant = odt.toInstant() ; // Basic building-block class in java.time, representing a moment as seen in UTC.
long millisecondsSinceEpoch1970 = instant.toEpochMilli() ;
Your title mentions Firebase, but that seems irrelevant to your Question. so I will ignore that topic.
All the content in this Answer has been covered many times already on Stack Overflow. Search to learn more.
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.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
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. Hibernate 5 & JPA 2.2 support java.time.
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 brought 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 (26+) bundle implementations of the java.time classes.
For earlier Android (<26), a process known as API desugaring brings a subset of the java.time functionality not originally built into Android.
If the desugaring does not offer what you need, the ThreeTenABP project adapts ThreeTen-Backport (mentioned above) to Android. See How to use ThreeTenABP….
I have received a string in format "yyyy-MM-dd'T'HH:mm:ssXXX"
e.g. "2020-06-01T11:04:02+02:00"
I want to convert it into "yyyy-MM-dd'T'HH:mm:ss:SSSZ"
e.g "2020-06-01T11:04:02.000+0200"
I don't know the time zone actually. It should take from that last part of string as it is.
I have tried but it is taking my local time and time zone when I convert string to date(i.e IST).
SimpleDateFormat sd1 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssXXX");
//sd1.setTimeZone(TimeZone.getTimeZone("PST"));
Date dt = sd1.parse("2020-06-01T11:04:02+02:00");
SimpleDateFormat sd2 = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss:SSSZ");
System.out.println(sd2.format(dt));
Output:
2020-06-01T14:34:02:000+0530
Only date is right, time and timezone has changed.
I know I am doing it wrong, it will be really helpful if someone can tell me how can I do this.
Thanks for the help.
OffsetDateTime
You said:
I have received a string in format "yyyy-MM-dd'T'HH:mm:ssXXX"
e.g. "2020-06-01T11:04:02+02:00"
No need to define a formatting pattern. Your input complies with the ISO 8601 standard.
These standard formats are used by default in the java.time classes when parsing/generating strings.
Your input should be parsed as a OffsetDateTime.
String input = "2020-06-01T11:04:02+02:00" ;
OffsetDateTime odt = OffsetDateTime.parse( input ) ;
odt.toString(): 2020-06-01T11:04:02+02:00
Offset-from-UTC versus time zone
You said:
I don't know the time zone actually.
That +02:00 on the end is not a time zone. That text represents a mere offset-from-UTC. An offset is just a number of hours-minutes-seconds, positive or negative. A time zone is much more. A time zone is a history of the past, present, and future changes to the offset used by the people of a particular region. A time zone has a name in the format of Continent/Region, such as Europe/Brussels or Africa/Cairo.
You can adjust from a mere offset to a specific time zone. Apply a ZoneId to get a ZonedDateTime.
ZoneId z = ZoneId.of( "Asia/Kolkata" ) ;
ZonedDateTime zdt = odt.atZoneSameInstant( z ) ;
zdt.toString(): 2020-06-01T14:34:02+05:30[Asia/Kolkata]
You said:
It should take from that last part of string as it is.
I am not sure what you meant by that. If you parse your input as an OffsetDateTime, that object knows its offset, accessible as a ZoneOffset.
ZoneOffset offset = odt.getOffset() ;
See the code shown in this Answer run live at IdeOne.com.
offset.toString(): +02:00
Formatting strings
You said:
I want to convert it into "yyyy-MM-dd'T'HH:mm:ss:SSSZ"
e.g "2020-06-01T11:04:02.000+0200"
Not sure what you mean here. Do you mean to force the display of milliseconds even if the value is zero? Firstly, you should know that java.time objects have a resolution of nanoseconds for up to nine decimal digits, much finer that the milliseconds shown in 3 digits of a decimal fraction. Secondly, forcing display of fractional second has been covered on Stack Overflow, such as here. Always search Stack Overflow before posting.
Or do you mean displaying the offset without a COLON character as a delimiter between minutes and seconds?
I advise against this. While dropping the COLON is technically allowed by the ISO 8601 standard, I have seen more than one software library or system fail to handle an offset without that delimiter. Ditto for using an offset of hours without the minutes. I advise always using the hours, the minutes, and the delimiter.
If you insist, use DateTimeFormatter with a formatting pattern. Study the Javadoc, keeping mind that the formatting codes are (a) case-sensitive, and (b) sensitive to repeating the character 0, 1, or more times. Here we use xx to get the hours and minutes of an offset without the COLON character delimiting. (Again, I do not recommend that format.)
Code shown in that same IdeOne.com page.
DateTimeFormatter f = DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSxx" ) ;
String output = odt.format( f ) ;
output: 2020-06-01T11:04:02.000+0200
Date::toString injects time zone
You said:
I have tried but it is taking my local time and time zone when I convert string to date(i.e IST).
The java.util.Date::toString method tells a lie. While well-intentioned, that method unfortunately applies the JVM’s current default time zone to the Date value as it generates the text. The Date class actually represents a moment in UTC. This is one of many reasons to never use Date. That class nowadays is replaced by java.time.Instant.
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.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
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. Hibernate 5 & JPA 2.2 support java.time.
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 first suggestion I would make to you is to switch from using the Date object to LocalDateTime (java 8+)
Using the new API would work in this way
String YOUR_DATE_TIME_PATTERN = "yyyy-MM-dd'T'HH:mm:ssXXX";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern(YOUR_DATE_TIME_PATTERN);
LocalDateTime dateTime = LocalDateTime.parse(input_date, formatter);
//Then you can set your timezone in this way - remember to replace the values with the proper timezone you want.
ZonedDateTime zonedUTC = dateTime.atZone(ZoneId.of("UTC"));
ZonedDateTime zonedIST = zonedUTC.withZoneSameInstant(ZoneId.of("Asia/Kolkata"));
let me know if that works for you
To elaborate the comment and picking up on #Daniel Vilas-Boas answer, you should go for Java8 and I think what you want is something like:
public static void main(String[] args) {
String YOUR_DATE_TIME_PATTERN = "yyyy-MM-dd'T'HH:mm:ssXXX";
String YOUR_NEW_DATE_TIME_PATTERN = "yyyy-MM-dd'T'HH:mm:ss:SSSZ";
DateTimeFormatter formatter = DateTimeFormatter.ofPattern(YOUR_DATE_TIME_PATTERN);
DateTimeFormatter newFormatter = DateTimeFormatter.ofPattern(YOUR_NEW_DATE_TIME_PATTERN);
ZonedDateTime zonedDateTime = ZonedDateTime.parse("2020-06-01T11:04:02+02:00", formatter);
ZoneId from = ZoneId.from(zonedDateTime);
System.out.println(from);
ZonedDateTime zonedIST = zonedDateTime.withZoneSameInstant(ZoneId.of("Asia/Kolkata"));
System.out.println(zonedDateTime.format(newFormatter));
System.out.println(zonedIST.format(newFormatter));
}
The prints should print:
2020-06-01T11:04:02:000+0000
2020-06-01T16:34:02:000+0530
EDIT
Included ZoneId to allow handling different timezones.
I'm a little bit frustrated of java 8 date format/parse functionality. I was trying to find Jackson configuration and DateTimeFormatter to parse "2018-02-13T10:20:12.120+0000" string to any Java 8 date, and didn't find it.
This is java.util.Date example which works fine:
Date date = new SimpleDateFormat("yyyy-MM-dd'T'hh:mm:ss.SSSZZZ")
.parse("2018-02-13T10:20:12.120+0000");
The same format doesn't work with new date time api
ZonedDateTime dateTime = ZonedDateTime.parse("2018-02-13T10:20:12.120+0000",
DateTimeFormatter.ofPattern("yyyy-MM-dd'T'hh:mm:ss.SSSZZZ"));
We should be able to format/parse date in any format suitable for FE UI application. Maybe I misunderstand or mistake something, but I think java.util.Date gives more format flexibility and easier to use.
tl;dr
Until bug is fixed:
OffsetDateTime.parse(
"2018-02-13T10:20:12.120+0000" ,
DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSX" )
)
When bug is fixed:
OffsetDateTime.parse( "2018-02-13T10:20:12.120+0000" )
Details
You are using the wrong classes.
Avoid the troublesome old legacy classes such as Date, Calendar, and SimpleDateFormat. Now supplanted by the java.time classes.
The ZonedDateTime class you used is good, it is part of java.time. But it is intended for a full time zone. Your input string has merely an offset-from-UTC. A full time zone, in contrast, is a collection of offsets in effect for a region at different points in time, past, present, and future. For example, with Daylight Saving Time (DST) in most of North America, the offsets change twice a year growing smaller in the Spring as we shift clocks forward an hour, and restoring to a longer value in the Autumn when we shift clocks back an hour.
OffsetDateTime
For only an offset rather than a time zone, use the OffsetDateTime class.
Your input string complies with the ISO 8601 standard. The java.time classes use the standard formats by default when parsing/generating strings. So no need to specify a formatting pattern.
OffsetDateTime odt = OffsetDateTime.parse( "2018-02-13T10:20:12.120+0000" );
Well, that should have worked. Unfortunately, there is a bug in Java 8 (at least up through Java 8 Update 121) where that class fails to parse an offset omitting the colon between hours and minutes. So the bug bites on +0000 but not +00:00. So until a fix arrives, you have a choice of two workarounds: (a) a hack, manipulating the input string, or (b) define an explicit formatting pattern.
The hack: Manipulate the input string to insert the colon.
String input = "2018-02-13T10:20:12.120+0000".replace( "+0000" , "+00:00" );
OffsetDateTime odt = OffsetDateTime.parse( input );
DateTimeFormatter
The more robust workaround is to define and pass a formatting pattern in a DateTimeFormatter object.
String input = "2018-02-13T10:20:12.120+0000" ;
DateTimeFormatter f = DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSX" );
OffsetDateTime odt = OffsetDateTime.parse( input , f );
odt.toString(): 2018-02-13T10:20:12.120Z
By the way, here is a tip: I have found that with many protocols and libraries, your life is easier if your offsets always have the colon, always have both hours and minutes (even if minutes are zero), and always use a padding zero (-05:00 rather than -5).
DateTimeFormatterBuilder
For a more flexible formatter, created via DateTimeFormatterBuilder, see this excellent Answer on a duplicate Question.
Instant
If you want to work with values that are always in UTC (and you should), extract an Instant object.
Instant instant = odt.toInstant();
ZonedDateTime
If you want to view that moment through the lens of some region’s wall-clock time, apply a time zone.
ZoneId z = ZoneId.of( "America/Montreal" );
ZonedDateTime zdt = odt.atZoneSameInstant( z );
See this code run live at IdeOne.com.
All of this has been covered many times in many Answers for many Questions. Please search Stack Overflow thoroughly before posting. You would have discovered many dozens, if not hundreds, of examples.
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, 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.
Short: Not a bug, just your pattern is wrong.
Please use the type OffsetDateTime which is especially designed for time zone offsets and use a pattern this way:
OffsetDateTime odt =
OffsetDateTime.parse(
"2018-02-13T10:20:12.120+0000" ,
DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSZZZ" )
)
Problems in detail:
a) 12-hour-clock versus 24-hour-clock
"h" indicates the hour of AM/PM on a 12-hour-clock but you obviously need "H" for the 24-hour-clock as required by ISO-8601.
b) The form of zero offset
If you want to parse zero offset like "+0000" instead of "Z" (as described in ISO-paper) you should not use the pattern symbol "X" but "ZZZ". Citing the pattern syntax:
Offset Z: This formats the offset based on the number of pattern
letters. One, two or three letters outputs the hour and minute,
without a colon, such as '+0130'. The output will be '+0000' when the
offset is zero.
c) Your input is NOT ISO-8601-compatible therefore no bug in Java
Your assumption that "2018-02-13T10:20:12.120+0000" shall be valid ISO is wrong because you are mixing basic format (in the offset part) and extended format which is explicitly prohibited in ISO-paper (see sections 4.3.2 (example part) and 4.3.3d). Citing ISO-8601:
[...]the expression shall either be completely in basic format, in which
case the minimum number of separators necessary for the required
expression is used, or completely in extended format[...]
The statement of B. Bourque that java.time has a bug is based on the same wrong expectation about ISO-compatibility. And the documentation of let's say ISO_OFFSET_DATE_TIME describes the support of the extended ISO-format only. See also the related JDK issue. Not all ISO-8601-variants are directly supported hence a pattern-based construction of the parser in the right way is okay.
if offset +0000 try this
DateTimeFormatter f = DateTimeFormatter.ofPattern( "uuuu-MM-dd'T'HH:mm:ss.SSSX" )
LocalDate from =LocalDate.parse("2018-02-13T10:20:12.120+0000",f);
I'm working on a project which takes rrule to generate next occurrences. But I'm not able to understand what i need to put in UNTIL tag of rrule.
String str="RRULE:FREQ=MONTHLY;UNTIL=20190625T000000Z;INTERVAL=2;";
Idk how to convert date into "20190625T000000Z".I'm using rfc 2445 java library. If user enters the date as a string for example :25/06/2019......i need to set this value in UNTIL tag as shown above. If I set the default value in UNTIL then it works but not when i make it user friendly.. I'm taking all the values from user as start date, end date, interval, Byday,Until... But idk what value to set in UNTIL.
If someone can help.. Thanks in advance.
Parsing basic ISO 8601 format
Your input 20190625T000000Z is the “basic” variation of standard ISO 8601 format to represent a moment in UTC. The word “basic” means minimizing the use of delimiters (I do not recommend this, as it makes the string less readable by humans).
Defining a formatting pattern to match input.
String input = "20190625T000000Z";
DateTimeFormatter f = DateTimeFormatter.ofPattern( "uuuuMMdd'T'HHmmssX" );
OffsetDateTime odt = OffsetDateTime.parse( input , f );
Dump to console.
System.out.println("odt.toString(): " + odt);
See this code run live at IdeOne.com.
odt.toString(): 2019-06-25T00:00Z
Translating date to moment
If user enters the date as a string for example :25/06/2019......i need to set this value in UNTIL tag as shown above
First, parse that input string into a LocalDate, representing a date-only value, without time-of-day and without time zone.
DateTimeFormatter fDateOnly = DateTimeFormatter.ofPattern( "dd/MM/uuuu" );
LocalDate ld = LocalDate.parse( "25/06/2019" , fDateOnly );
ld.toString(): 2019-06-25
As for translating that date into a moment (a date with time-of-day in a zone or offset-from-UTC), that is trickier than it sounds intuitively.
A date such as the 25th of June 2019 represents an entire day. And a theoretical date at that. The moments when a day begins and ends varies around the globe by time zone. A new day begins much earlier in Tokyo Japan than in Paris France, and even later in Montréal Québec.
Another issue is that the day does not always begin at 00:00:00. Because of anomalies such as Daylight Saving Time (DST), the first moment of a day on some dates in some zones may be something like 01:00:00. Let the java.time classes determine first moment.
ZoneId z = ZoneId.of( "Africa/Tunis" );
ZonedDateTime zdt = ld.atStartOfDay( z );
zdt.toString(): 2019-06-25T00:00+01:00[Africa/Tunis]
That ZonedDateTime object represents a specific moment. But it uses the wall-clock time adopted by the people of a particular region (a time zone). Your goal is a moment in UTC. Fortunately, we can adjust from the zone to UTC by converting to an OffsetDateTime (a date and time with a context of offset-from-UTC rather than a time zone). We can specify UTC (an offset of zero) by the ZoneOffset.UTC constant.
OffsetDateTime odt = zdt.toOffsetDateTime().withOffsetSameInstant( ZoneOffset.UTC );
odt.toString(): 2019-06-24T23:00Z
Note how 00:00 on the 25th in Tunisia is 11 PM “yesterday” the 24th in UTC. Same moment, same simultaneous point on the timeline, but two different wall-clock times.
Lastly, we need a string in that “basic” ISO 8601 format. Use the same formatter we defined above.
DateTimeFormatter fIso8601DateTimeBasic = DateTimeFormatter.ofPattern( "uuuuMMdd'T'HHmmssX" );
String output = odt.format( fIso8601DateTimeBasic );
output: 20190624T230000Z
See this code run live at IdeOne.com.
Just what is the difference between a time zone and an offset-from-UTC? An offset is merely a number of hours-minutes-seconds. Nothing more, nothing less, just a number (well, three numbers). A time zone is much more. A time zone is a history of past, present, and future changes to the offset used by the people of a particular region. For example, in most of North America, the offset changes twice a year, springing ahead an hour and then falling back an hour (the lunacy of Daylight Saving Time (DST)).
Tip: Date-time handling is surprisingly tricky and slippery. If you are working with calendars and the iCalendar spec for data exchange, I suggest you take a long while to study the concepts and practice with the industry-leading java.time classes.
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.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
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.
I got the following date format that I get from an API (Yes I tried to get them to change the API... dailywtf story):
\/Date(1310481956000+0200)\/
How can I convert this into a Java Date? (java.util.Date)
This comes from a .NET JSON web service.
Without knowing what the date/time string stands for, let me make a guess.
The 1310481956000 looks to be milliseconds after epoch, and the +0200 an offset relative to GMT.
The following code seem to indicate it as well:
final TimeZone tz = TimeZone.getTimeZone("GMT+0200");
final Calendar cal = Calendar.getInstance(tz);
cal.setTimeInMillis(1310481956000L);
final SimpleDateFormat f = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z");
f.setTimeZone(tz);
System.out.println(f.format(cal.getTime()));
Prints 2011-07-12 16:45:56 GMT+02:00
How can I convert this into a Java Date? (java.util.Date)
First, get "them" to clearly and precisely tell you exactly what that date format means. (If they won't or can't you could guess; see below.)
Next write a custom parser to parse the String and extract the information content.
Finally, convert the information content into a form that matches one of the Date constructors and create an instance.
My guess is that the 1310481956000 part is the number of milliseconds since the UNIX epoch (1970/01/01T00:00) and that the 0200 represents a timezone offset of 2 hours (MET?). However, you shouldn't rely on a guess. Get "them" to give you the specification, or at least a number of examples and the actual times/timezones that they correspond to.
You'll have to get the format from the API provider but it seems like a epoch + an offset for time zones. To convert it you could try.
final String fromAPI = "1310481956000+0200"
final String epochTime = fromAPI.substring(0, fromAPI.indexOf("+"));
final String timeZoneOffSet = fromAPI.substring(fromAPI.indexOf("+"), fromAPI.size());
Date date = new Date(Long.parseLong(epochTime));
Notice i'm not doing anything with the time zone (if that's what it is). You'll have to deal with that but this should get you on the right path.
tl;dr
Instant.ofEpochMilli(
java.lang.Long.parseLong( "1310481956000" )
).atOffset( ZoneOffset.of( "+0200" ) )
Using java.time
The accepted Answer is correct but outdated. The modern way to handle this is through the java.time classes.
The input is ambiguous. Is it a count from the Unix epoch reference date-time of first moment of 1970 in UTC 1970-01-01T00:00:00:Z and then adjusted by two hours ahead of UTC? If so, this example code seen here works.
First parse that input number as a Instant. The Instant class represents a moment on the timeline in UTC with a resolution of nanoseconds (up to nine (9) digits of a decimal fraction).
Extract the first portion of your string and parse as a long.
long millisSinceEpoch = java.lang.Long.parseLong( "1310481956000" );
Instant instant = Instant.ofEpochMilli( millisSinceEpoch );
instant.toString(): 2011-07-12T14:45:56Z
Extract the last portion of your string and parse as a ZoneOffset.
ZoneOffset offset = ZoneOffset.of( "+0200" );
Apply the offset to the Instant to get an OffsetDateTime.
OffsetDateTime odt = instant.atOffset( offset );
odt.toString(): 2011-07-12T16:45:56+02:00
Note that an offset-from-UTC is not a time zone. A zone is an offset plus a set of rules for handling anomalies such as Daylight Saving Time (DST).
Avoid java.util.Date whenever possible. But if you must use one, you can convert to/from java.time. Look to new conversion methods added to the old classes.
java.util.Date d = java.util.Date.from( odt.toInstant() );
d.toString(): Tue Jul 12 14:45:56 GMT 2011
See live code at IdeOne.com covering this entire example.
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.
Where to obtain the java.time classes?
Java SE 8 and 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 SE 7
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
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.