Fix DateTimeParseException: “Unable to obtain LocalDateTime from TemporalAccessor”

1. Overview

Handling date and time in Java using the java.time package is efficient, but sometimes we may encounter the DateTimeParseException error with the message “Unable to obtain LocalDateTime from TemporalAccessor“. This issue typically arises due to an incompatibility between the expected date-time format and the actual input.

This article explains why this exception occurs, explores its common causes, and provides effective strategies to prevent and fix it.

2. Understanding the Exception

The “Unable to obtain LocalDateTime from TemporalAccessor” exception occurs when Java’s date-time parser fails to extract a valid LocalDateTime object from a TemporalAccessor, such as LocalDate, ZonedDateTime, or OffsetDateTime. The root cause is often an improperly formatted or incomplete input string.

LocalDateTime requires both a date and a time component. If an input string lacks required components or doesn’t match the expected format, the parsing process fails, resulting in this exception. We often assume that Java can automatically infer missing time values, but this isn’t the case.

Let’s consider the following example, where a date string is incorrectly parsed as LocalDateTime:

public static void main(String[] args) {
    String dateTimeStr = "20250327";
    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd");
    LocalDateTime localDateTime = LocalDateTime.parse(dateTimeStr, formatter);
}

When executed, this code throws the following exception:

java.time.format.DateTimeParseException: Text '20250327' could not be parsed: Unable to obtain LocalDateTime from TemporalAccessor: {},ISO resolved to 2025-03-27 of type java.time.format.Parsed

The error occurs because LocalDateTime requires both date and time, but the input only contains a date.

3. Common Causes and Solutions

Before diving into specific causes, it’s important to recognize that date-time parsing issues often stem from assumptions about how input data is structured. The java.time API is strict about enforcing format rules, meaning that any deviation, such as a missing time component, an incorrect format, or an unexpected time zone, can trigger an exception.

Below, we explore the most common causes of this error and look at solutions to handle them effectively.

3.1. Missing Time Component in Input String

When an input string contains only a date, such as “2024-03-25“, but is parsed as a LocalDateTime, the parsing fails because LocalDateTime requires both a date and a time component. This results in a DateTimeParseException.

To resolve this, we can parse the date as a LocalDate instead of LocalDateTime:

LocalDate date = LocalDate.parse("2024-03-25", DateTimeFormatter.ISO_LOCAL_DATE);

Alternatively, if we require LocalDateTime, we can append a default time value to the input string, such as “T00:00:00“:

String dateTimeStr = "2024-03-25T00:00:00";
LocalDateTime dateTime = LocalDateTime.parse(dateTimeStr, DateTimeFormatter.ISO_LOCAL_DATE_TIME);

3.2. Parsing DayOfWeek as LocalDateTime

The DayOfWeek enum represents a day of the week (e.g., MONDAY, FRIDAY), but it doesn’t include any date or time information. Attempting to use a DayOfWeek value directly as a LocalDateTime results in an exception since LocalDateTime requires both a date and a time.

If we need a complete LocalDateTime for a specific weekday, we can determine the next occurrence of that day and combine it with a chosen time:

DayOfWeek targetDay = DayOfWeek.FRIDAY;
LocalDate today = LocalDate.now();
LocalDate nextTargetDate = today.with(TemporalAdjusters.next(targetDay));

LocalTime time = LocalTime.of(14, 30);
LocalDateTime dateTime = LocalDateTime.of(nextTargetDate, time);

This approach ensures that we correctly associate the DayOfWeek value with an actual date before combining it with a time to form a valid LocalDateTime.

3.3. Parsing LocalTime as LocalDateTime

When an input string contains only a time, such as “14:30:00“, and is parsed as a LocalDateTime, it fails because LocalDateTime requires both a date and a time component. LocalTime provides only the time portion, so parsing it as LocalDateTime results in an exception.

To fix this, we combine LocalTime with a LocalDate to form a complete LocalDateTime:

LocalDate date = LocalDate.of(2024, 3, 25);
LocalTime time = LocalTime.parse("14:30:00");
LocalDateTime dateTime = LocalDateTime.of(date, time);

3.4. Parsing YearMonth as LocalDateTime

The YearMonth class represents only the year and month, without any specific day or time information. As a result, attempting to parse a YearMonth as a LocalDateTime fails since LocalDateTime requires both a complete date and a time.

To address this, we can use the YearMonth class for operations requiring only the year and month. Alternatively, if we need a complete LocalDateTime, we can combine YearMonth with a specific day and time:

YearMonth yearMonth = YearMonth.parse("2024-03", DateTimeFormatter.ofPattern("yyyy-MM"));
LocalDate date = yearMonth.atDay(1);
LocalTime time = LocalTime.of(14, 30);
LocalDateTime dateTime = LocalDateTime.of(date, time);

3.5. Parsing MonthDay as LocalDateTime

The MonthDay class represents only a month and day (e.g., “03-25“) and doesn’t include a year or time component. Parsing MonthDay as a LocalDateTime fails because LocalDateTime requires both a complete date and a time.

To fix this, we can use MonthDay if only the month and day are required. Alternatively, if we need a LocalDateTime, we combine MonthDay with a specific year and time:

MonthDay monthDay = MonthDay.parse("03-25", DateTimeFormatter.ofPattern("MM-dd"));
LocalDate date = LocalDate.of(2024, monthDay.getMonth(), monthDay.getDayOfMonth());
LocalTime time = LocalTime.of(14, 30);
LocalDateTime dateTime = LocalDateTime.of(date, time);

4. Conclusion

The DateTimeParseException error “Unable to obtain LocalDateTime from TemporalAccessor” typically occurs due to missing or incorrectly formatted date-time information, or improper handling of time zones.

To avoid this error, we should ensure that the input format matches the expected pattern and use the appropriate Java date-time class (LocalDate, LocalDateTime, ZonedDateTime, or OffsetDateTime).

By following these best practices, date-time values can be parsed and managed efficiently without errors.