convert String "yyyy-MM-dd" to LocalDateTime

Question

Is there any way to convert a date String to LocalDateTime where the format "yyyy-MM-dd" ?

If I try this:

DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDateTime ldt = LocalDateTime.parse(string, DATEFORMATTER);

I got this exception:

java.time.format.DateTimeParseException: Text '2017-03-13' could not be parsed: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2017-03-13 of type java.time.format.Parsed
    at java.time.format.DateTimeFormatter.createError(DateTimeFormatter.java:1920)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1855)
    at java.time.LocalDateTime.parse(LocalDateTime.java:492)
    at hu.npsh.workforce.utils.Util.stringToLocalDateTime(Util.java:284)
    at hu.npsh.workforce.utils.util.StringLocalDateTimeConversionTest.stringToLocalDateTimeTest(StringLocalDateTimeConversionTest.java:35)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: java.time.DateTimeException: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2017-03-13 of type java.time.format.Parsed
    at java.time.LocalDateTime.from(LocalDateTime.java:461)
    at java.time.format.Parsed.query(Parsed.java:226)
    at java.time.format.DateTimeFormatter.parse(DateTimeFormatter.java:1851)
    ... 26 more
Caused by: java.time.DateTimeException: Unable to obtain LocalTime from TemporalAccessor: {},ISO resolved to 2017-03-13 of type java.time.format.Parsed
    at java.time.LocalTime.from(LocalTime.java:409)
    at java.time.LocalDateTime.from(LocalDateTime.java:457)
    ... 28 more

I know that the main problem, that the pattern does not contain the hour and the minute.. But what if I want a create a method what gets a String and a DateTimeFormatter and I want to return with LocalDateTime

Is there a correct, nice solution?

EDIT:

My goal, making a method what get a String and a DateTimeFormatter And returns with a LocalDateTime . The Pattern can be anything (what is valid).

Answer 1

Use LocalDate to create a localDate and then you can add the timepart if you need it:

    DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    LocalDate ld = LocalDate.parse("2017-03-13", DATEFORMATTER);
    LocalDateTime ldt = LocalDateTime.of(ld, LocalDateTime.now().toLocalTime());
    System.out.println(ldt);

or LocalDateTime

ldt = LocalDateTime.of(ld, LocalDateTime.MIN.toLocalTime());

if you just need an empty timepart

EDIT:

Look at this solution with this you can build your dynamic parser:

    DateTimeFormatter DATEFORMATTER1 = DateTimeFormatter.ofPattern("yyyy-MM-dd");

    DateTimeFormatter DATEFORMATTER = new DateTimeFormatterBuilder().append(DATEFORMATTER1)
    .parseDefaulting(ChronoField.HOUR_OF_DAY, 0)
    .parseDefaulting(ChronoField.MINUTE_OF_HOUR, 0)
    .parseDefaulting(ChronoField.SECOND_OF_MINUTE, 0)
    .toFormatter();

    //DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyy-MM-dd");
    LocalDateTime ldt = LocalDateTime.parse("2017-03-13", DATEFORMATTER);

Answer 2

You can not convert "2017-03-13" to a LocalDateTime since there is no time information in the string, only date. You can convert it to a LocalDate

DateTimeFormatter dateformatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate ld = LocalDate.parse("2017-03-13", dateformatter);

after this we can covert it to LocalDateTime

LocalDateTime ldt = ld.atStartOfDay();

Answer 3

For start of the day you can use:

LocalDate.parse("2017-10-18", DateTimeFormatter.ofPattern("yyyy-MM-dd"))
.atStartOfDay().atOffset(ZoneOffset.UTC).format(DateTimeFormatter.ISO_DATE_TIME)

For end of the day you can use:

LocalDate.parse("2017-10-18", DateTimeFormatter.ofPattern("yyyy-MM-dd"))                        
.atStartOfDay().plusHours(23).plusMinutes(59).plusSeconds(59).atOffset(ZoneOffset.UTC).format(DateTimeFormatter.ISO_DATE_TIME)

For localDateTime you can use:

LocalDate.parse("2017-10-18", DateTimeFormatter.ofPattern("yyyy-MM-dd")).atTime(LocalTime.now())
.atOffset(ZoneOffset.UTC).format(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'"))

Result:

2017-10-18T00:00:00Z
2017-10-18T23:59:59Z
2017-10-18T14:45:35Z

Answer 4

一个班轮怎么样？

LocalDateTime.parse("2017-03-13" + " 00:00", DateTimeFormatter.ofPattern("yyyy-MM-dd hh:mm"));

Answer 5

If you have a date in a string with the format "yyyyMMdd" and want to convert into localDate then follow these steps:

public static void processDate() {
    DateTimeFormatter DATEFORMATTER = DateTimeFormatter.ofPattern("yyyyMMdd");
    LocalDate ld = LocalDate.parse("20200511", DATEFORMATTER);
    System.out.println(ld.toString());
}

The output is in "yyyy-MM-dd" format:

2020-05-11

Answer 6

public static LocalDateTime formatLocalDateTime(String text, DateTimeFormatter pattern) {
    if (StringUtils.isEmpty(text)) {
        throw new RuntimeException("can not format String :" + text);
    }
    Optional.ofNullable(pattern).orElseThrow(() -> new RuntimeException("pattern can not be null"));
    TemporalAccessor temporalAccessor= pattern.parse(text);
    try {
        Field date=temporalAccessor.getClass().getDeclaredField("date");
        date.setAccessible(true);
        if(!Optional.ofNullable(date.get(temporalAccessor)).isPresent()){
            date.set(temporalAccessor, LocalDate.of(1970,1,1));
        }
        Field time=temporalAccessor.getClass().getDeclaredField("time");
        time.setAccessible(true);
        if(!Optional.ofNullable(time.get(temporalAccessor)).isPresent()){
            time.set(temporalAccessor, LocalTime.MIN);
        }
        return LocalDateTime.from(temporalAccessor);
    } catch (ReflectiveOperationException e) {
        throw new RuntimeException("format error :"+e.getMessage());
    }
}

Answer 7

Use Joda-Time-XX.jar it has DateTimeFormatter to convert date to date time format. Either you can provide date time in (yyyy-MM-dd HH:mm:ss format) or date alone. In both the cases you will get date and time.

DateTimeFormatter dateTimeFormatter = DateTimeFormat.forPattern("yyyy-MM-dd");
DateTime dateTime =  dateTimeFormatter.parseDateTime(date);