Fixing UnsupportedTemporalTypeException: Unsupported Field: InstantSeconds

1. Overview

When working with dates, we often leverage the Date-Time API. However, manipulating or accessing temporal data may lead to errors and exceptions when done improperly. One such specific exception is UnsupportedTemporalTypeException: “Unsupported Field: InstantSeconds” which typically denotes that the field InstantSeconds isn’t supported by the specified temporal object.

So, in this short tutorial, we’ll learn how to avoid this exception when working with the Date-Time API.

2. Practical Example

Before diving into the solution, let’s use a practical example to understand the root cause of the exception.

According to the documentation, UnsupportedTemporalTypeException signals that a ChronoField or ChronoUnit isn’t supported. In other words, the exception occurs when an unsupported field is used with a temporal object that doesn’t support that specific field.

Typically, the stack trace “Unsupported Field: InstantSeconds” says it all. It indicates that there’s something wrong with the field InstantSeconds which represents the concept of the sequential count of seconds from the epoch.

In short, not all temporal objects provided by the Date-Time API support this field. For example, attempting to apply operations involving InstantSeconds to LocalDateTime, LocalDate, and LocalTime results in UnsupportedTemporalTypeException.

Now, let’s see how to reproduce the exception in practice. To do so, we’ll try to convert a LocalDateTime to Instant:

@Test
void givenLocalDateTime_whenConvertingToInstant_thenThrowException() {
    assertThatThrownBy(() -> {
        LocalDateTime localDateTime = LocalDateTime.now();
        long seconds = localDateTime.getLong(ChronoField.INSTANT_SECONDS);
        Instant instant = Instant.ofEpochSecond(seconds);
    }).isInstanceOf(UnsupportedTemporalTypeException.class)
        .hasMessage("Unsupported field: InstantSeconds");
}

As we can see, the test failed because we attempted to access ChronoField.INSTANT_SECONDS using an instance of LocalDateTime.

In short, LocalDateTime doesn’t support INSTANT_SECONDS which denotes a single specific instant because the same LocalDateTime object could represent multiple different instants depending on the time zone. For instance, “2024-06-22T11:20:33” in New York differs from “2024-06-22T11:20:33” in Tokyo.

3. Solution

As we noted earlier, the main reason why LocalDateTime doesn’t support ChronoField.INSTANT_SECONDS is that it lacks sufficient information about the time zone to determine the exact instantaneous point on the global timeline.

So, the easiest solution would be to set the time zone before converting the LocalDateTime to Instant. For that purpose, we can use the ZonedDateTime class:

@Test
void givenLocalDateTime_whenConvertingUsingTimeZone_thenDoNotThrowException() {
    LocalDateTime localDateTime = LocalDateTime.now();
    ZonedDateTime zonedDateTime = localDateTime.atZone(ZoneId.systemDefault());
    assertThatCode(() -> {
        Instant instant = zonedDateTime.toInstant();
    }).doesNotThrowAnyException();
}

Here, we used the atZone() method to return a ZonedDateTime object formed from the given LocalDateTime at the specified time zone. Then, we called toInstant() to calculate the instant represented by the date-time based on the provided time zone.

4. Conclusion

In this short article, we learned the root cause behind UnsupportedTemporalTypeException. Furthermore, we saw how to reproduce and fix it in practice.

As always, the full source code of the examples is available over on GitHub.