We Keep Coding

Convert String without ZonedId to OffsetDateTime

I would like to convert an String to OffsetDateTime datatype. The string has the following shape:
2017-11-27T19:06:03
I've tried two approaches:
Approach 1
public static OffsetDateTime convertString(String timestamp) {
java.time.format.DateTimeFormatter formatter = new java.time.format.DateTimeFormatterBuilder()
.parseCaseInsensitive()
.append(java.time.format.DateTimeFormatter.ISO_LOCAL_DATE)
.appendLiteral('T')
.appendValue(HOUR_OF_DAY, 2)
.appendLiteral(':')
.appendValue(MINUTE_OF_HOUR, 2)
.optionalStart()
.appendLiteral(':')
.appendValue(SECOND_OF_MINUTE, 2)
.toFormatter();
return OffsetDateTime.parse(timestamp, formatter);
}
Approach 2:
public static OffsetDateTime convertString(String timestamp) {
java.time.format.DateTimeFormatter parser = java.time.format.DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss");
java.time.LocalDateTime dt = java.time.LocalDateTime.parse(timestamp, parser);
ZonedDateTime zdt = ZonedDateTime.of(dt, java.time.ZoneId.of("UTC"));
return OffsetDateTime.from(zdt);
}
First approach does not work since it complains the following:
java.time.format.DateTimeParseException: Text '2017-11-27T19:02:42' could not be parsed: Unable to obtain OffsetDateTime from TemporalAccessor: {},ISO resolved to 2017-11-27T19:02:42 of type java.time.format.Parsed
For my understanding it comes from the fact that the string does not have ZoneId. How can I overwrite, on the formatter, the ZoneId so to ignore it?
The second approach comes from this question and works but it requieres 2 additional conversions, I would like to avoid those additional conversions.
Any help is going to be appreciated.

To get an OffsetDateTime from a string with no offset or time zone, you need to decide an offset or a way to get one. The most obvious way is if you know in which time zone the date-time is to be interpreted. For example:
OffsetDateTime dateTime = LocalDateTime.parse(timestamp)
.atZone(ZoneId.of("Asia/Chongqing"))
.toOffsetDateTime();
System.out.println(dateTime);
Output using the string from your question:
2017-11-27T19:06:03+08:00
Don’t be afraid of the two conversions from LocalDateTime to ZonedDateTime and then to OffsetDateTime. With java.time they are not only easy to do but also clear to read.
If you know the offset, just use that, then you need only one conversion (I am using a nonsensical offset for the example, so you will have to pick your own):
OffsetDateTime dateTime = LocalDateTime.parse(timestamp)
.atOffset(ZoneOffset.ofTotalSeconds(-36953));
System.out.println(dateTime);
Output:
2017-11-27T19:06:03-10:15:53
You may specify your desired offset as for example ZoneOffset.of("+08:00") or ZoneOffset.ofHours(8).
But to answer your question (it’s about time now).
How can I overwrite, on the formatter, the ZoneId so to ignore it?
DateTimeFormatter formatter = new DateTimeFormatterBuilder()
.append(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
.parseDefaulting(ChronoField.OFFSET_SECONDS, -36953)
.toFormatter();
OffsetDateTime dateTime = OffsetDateTime.parse(timestamp, formatter);
System.out.println(dateTime);
Output is the same as the previous one (and again you will need to pick an offset that makes sense in your situation).

Finally, I've solved this issue by the following code:
public static OffsetDateTime convertString(String timestamp) {
java.time.format.DateTimeFormatter formatter = new java.time.format.DateTimeFormatterBuilder()
.parseCaseInsensitive()
.append(java.time.format.DateTimeFormatter.ISO_LOCAL_DATE)
.appendLiteral('T')
.appendValue(HOUR_OF_DAY, 2)
.appendLiteral(':')
.appendValue(MINUTE_OF_HOUR, 2)
.optionalStart()
.appendLiteral(':')
.appendValue(SECOND_OF_MINUTE, 2)
.toFormatter();
return LocalDateTime.parse(timestamp, formatter)
.atOffset(java.time.ZoneOffset.UTC);
}

UnsupportedTemporalTypeException: Unsupported field: InstantSeconds

I have this code which is producing a timestamp and then parsing.
DateTimeFormatter formatter =
DateTimeFormatter
.ofPattern("yyyyMMdd kk:HH:ss.SSSZ")
.withLocale(Locale.getDefault())
.withZone(ZoneId.systemDefault());
Instant now = Instant.now();
String formatted = formatter.format(now);
Instant parsed = formatter.parse(formatted, Instant::from);
When it runs, the last line produces an exception:
java.time.format.DateTimeParseException: Text '20180123 12:12:45.648-0500' could not be parsed: Unable to obtain Instant from TemporalAccessor: {SecondOfMinute=45, NanoOfSecond=648000000, OffsetSeconds=-18000, MilliOfSecond=648, MicroOfSecond=648000, HourOfDay=12},ISO,America/New_York resolved to 2018-01-23 of type java.time.format.Parsed
Caused by: java.time.DateTimeException: Unable to obtain Instant from TemporalAccessor: {SecondOfMinute=45, NanoOfSecond=648000000, OffsetSeconds=-18000, MilliOfSecond=648, MicroOfSecond=648000, HourOfDay=12},ISO,America/New_York resolved to 2018-01-23 of type java.time.format.Parsed
Caused by: java.time.temporal.UnsupportedTemporalTypeException: **Unsupported field: InstantSeconds**
I replace the formatter with DateTimeFormatter.ISO_INSTANT, it works correctly. The actual data produced are nearly identical. What is the disconnect?
ISO_INSTANT: 2018-01-23T16:51:25.516Z
My Format: 20180119 23:59:59.999-0800
I am required to use my format. What is the problem here?

The problem is that your format does not completely represent an Instant because your format does not have a representation for minutes at all. The formatter can correctly go from Instant and output the result in your format because an Instant has all of the data that your format requires, but your format does not have everything that an Instant requires.
Try changing your pattern to yyyyMMdd kk:HH:mm:ss.SSS, and you will see that your code now works. Note the addition of mm.
If you absolutely require a minuteless pattern, you should make your own TemporalQuery to extract the information you require from the TemporalAccessor
In this case, I simply set minutes to 0:
public class MyQuery implements TemporalQuery<Instant> {
#Override
public Instant queryFrom(TemporalAccessor temporal) {
LocalDate ld = LocalDate.from(temporal);
LocalTime lt = LocalTime.of(temporal.get(ChronoField.HOUR_OF_DAY), 0, temporal.get(ChronoField.SECOND_OF_MINUTE), temporal.get(ChronoField.NANO_OF_SECOND));
return ZonedDateTime.of(ld, lt, ZoneId.systemDefault()).toInstant();
}
}
We can then use this TemporalQuery like this:
public class Test {
public static void main(String[] args) {
DateTimeFormatter formatter = DateTimeFormatter
.ofPattern("yyyyMMdd kk:HH:mm:ss.SSS")
.withLocale(Locale.getDefault())
.withZone(ZoneId.systemDefault());
Instant now = Instant.now();
String formatted = formatter.format(now);
System.out.println(formatted);
Instant ld = formatter.parse(formatted, new MyQuery());
}
}

I know that this is an old question but if you're looking for a short answer just add a locale and zone to the DateTimeFormatter, you may also use the default ones: .withLocale(Locale.getDefault()).withZone(ZoneId.systemDefault())
Here is an example of code:
Instant now = Instant.now();
System.out.println(now.toString());
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm:ss").withLocale(Locale.getDefault()).withZone(ZoneId.systemDefault());
System.out.println(formatter.format(now));
This code will use the current instant, output the sample, format it with the date time formatter and output the formatted instant.

Parse datetime without offset in OffsetDateTime java

Can I somehow parse a datetime that's without offset using OffsetDateTime.parse(....)
Java code:
DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS XXX");
OffsetDateTime date = OffsetDateTime.parse("2017-02-03 12:30:3000", FORMATTER);
I'm getting datetime as a String without offset, but need to parse it into OffsetDateTime, I know I need an offset here, but can I some how alter that String to insert default/dummy offset (maybe +00:00) & parse it using OffsetDateTime. The problem is that object has to be OffsetDateTime.

The simplest solution is to parse your string into a LocalDateTime and then convert:
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss");
OffsetDateTime date = LocalDateTime.parse("2017-02-03 12:30:30", formatter)
.atOffset(ZoneOffset.UTC);
This gives an OffsetDateTime of 2017-02-03T12:30:30Z, where Z means UTC or offset zero.
You can parse directly into an OffsetDateTime if you want:
DateTimeFormatter FORMATTER = new DateTimeFormatterBuilder()
.appendPattern("yyyy-MM-dd HH:mm:ss")
.parseDefaulting(ChronoField.OFFSET_SECONDS, 0)
.toFormatter();
OffsetDateTime date = OffsetDateTime.parse("2017-02-03 12:30:30", FORMATTER);
Finally, if you are required to use the formatter given in the question, altering the string to fit is of course an option. For example:
DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS XXX");
String fixedDateTimeString
= "2017-02-03 12:30:3000".replaceFirst("(\\d{2})0*$", "$1.000 +00:00");
OffsetDateTime date = OffsetDateTime.parse(fixedDateTimeString, FORMATTER);
As you can see, in the last example I have also kept the too many zeroes in the string I am using as a starting point, removing them in the same operation that appends the offset. The result is the same, 2017-02-03T12:30:30Z.
Edit: uuuu or yyyy for year in the format pattern string? Since the year is always in the common era (Anno Domini), either works. yyyy is for year of era and would be right of there was an era designator (like AD or BC, format pattern letter G). uuuu is a signed year, where year 0 means 1 BCE, -1 means 2 BCE, etc. There’s more in this question: uuuu versus yyyy in DateTimeFormatter formatting pattern codes in Java?

Actually I achieved it by:
DateTimeFormatter FORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSS");
OffsetDateTime.of(LocalDateTime.parse("2017-02-03 12:30:30", FORMATTER), ZoneOffset.UTC);

convert shortdate to LocalDate

Hi i have a short date format with me in the pattern E dd/MM , Is there any way i can convert it to LocalDate.
String date = "Thu 07/05";
String formatter = "E dd/MM";
final DateTimeFormatter formatter = DateTimeFormatter.ofPattern(pattern);
final LocalDate localDate = LocalDate.parse(date, formatter);`
But it throws an exception java.time.format.DateTimeParseException: Text 'Thu 07/05' could not be parsed: Unable to obtain LocalDate from TemporalAccessor: {MonthOfYear=5, DayOfMonth=7, DayOfWeek=4},ISO of type java.time.format.Parsed
Is there any way we can fix this issue ?

All you have is a month and a day - so you can create a MonthDay (to create a LocalDate you would also need a year):
MonthDay md = MonthDay.parse(date, formatter);
If you want a LocalDate, you can use the MonthDay as a starting point:
int year = Year.now().getValue();
LocalDate localDate = md.atYear(year);
Or alternatively you can use a default year in your formatter:
DateTimeFormatter formatter = new DateTimeFormatterBuilder()
.appendPattern(pattern)
.parseDefaulting(ChronoField.YEAR, year)
.toFormatter(Locale.US);
LocalDate localDate = LocalDate.parse(date, formatter);
The benefit of this method is that it will also check that the day of week (Thursday) is correct.

Why my pattern("yyyyMM") cannot parse with DateTimeFormatter (java 8)

When I using SimpleDateFormat, it can parse.
SimpleDateFormat format = new SimpleDateFormat("yyyyMM");
format.setLenient(false);
Date d = format.parse(date);
But When I use Java 8 DateTimeFormatter,
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMM");
LocalDate localDate = LocalDate.parse(date, formatter);
it throws
java.time.format.DateTimeParseException: Text '201510' could not be parsed: Unable to obtain LocalDate from TemporalAccessor: {Year=2015, MonthOfYear=10},ISO of type java
.time.format.Parsed
String value for date is "201510".

Ask yourself the question: which day should be parsed with the String "201510"? A LocalDate needs a day but since there is no day in the date to parse, an instance of LocalDate can't be constructed.
If you just want to parse a year and a month, you can use the YearMonth object instead:
YearMonth localDate = YearMonth.parse(date, formatter);
However, if you really want to have a LocalDate to be parsed from this String, you can build your own DateTimeFormatter so that it uses the first day of the month as default value:
DateTimeFormatter formatter = new DateTimeFormatterBuilder()
.appendPattern("yyyyMM")
.parseDefaulting(ChronoField.DAY_OF_MONTH, 1)
.toFormatter();
LocalDate localDate = LocalDate.parse(date, formatter);

You can use a YearMonth and specify the day you want (say the first for example):
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMM");
LocalDate localDate = YearMonth.parse(date, formatter).atDay(1);
Or if the day is irrelevant, just use a YearMonth.