java.time.Instant - get(INSTANT

JDK Tutorials - Herong's Tutorial Examples

∟java.time.Instant - get(INSTANT_SECONDS) Error

This section provides a tutorial example on how to use getLong() to retrieve INSTANT_SECONDS value. Using get() will result an exception.

While testing the get() method, I noticed an unexpected error with the INSTANT_SECONDS field. Here is the test program InstantSecondsError.java:

/* InstantSecondsError.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.time.Instant;
class InstantSecondsError {
   public static void main(String[] a) {
      java.io.PrintStream out = System.out;

      // Instant now = Instant.now();
      Instant now = Instant.parse("2014-04-01T05:48:41.750Z");
      out.println("toString() = " + now.toString());
      out.println("getEpochSecond() = " + now.getEpochSecond());
      out.println("getNano() = " + now.getNano());

      out.println("isSupported(DAY_OF_WEEK) = " + now.isSupported(
         java.time.temporal.ChronoField.DAY_OF_WEEK));
      // Unsupported field: DayOfWeek
      //      out.println("get(DAY_OF_WEEK) = " + now.get(
      //         java.time.temporal.ChronoField.DAY_OF_WEEK));

      out.println("isSupported(NANO_OF_SECOND) = " + now.isSupported(
         java.time.temporal.ChronoField.NANO_OF_SECOND));
      out.println("get(NANO_OF_SECOND) = " + now.get(
         java.time.temporal.ChronoField.NANO_OF_SECOND));

      out.println("isSupported(INSTANT_SECONDS) = " + now.isSupported(
         java.time.temporal.ChronoField.INSTANT_SECONDS));
      // Need to use getLong() to retrieve INSTANT_SECONDS value
      out.println("getLong(INSTANT_SECONDS) = " + now.getLong(
         java.time.temporal.ChronoField.INSTANT_SECONDS));
      // The get() call will throw an exception
      out.println("get(INSTANT_SECONDS) = " + now.get(
         java.time.temporal.ChronoField.INSTANT_SECONDS));
   }
}

When running InstantSecondsError.java with JDK 9 or higher, I got the following output:

herong> java InstantSecondsError.java

toString() = 2014-04-01T05:48:41.750Z
getEpochSecond() = 1396331321
getNano() = 750000000
isSupported(DAY_OF_WEEK) = false
isSupported(NANO_OF_SECOND) = true
get(NANO_OF_SECOND) = 750000000
isSupported(INSTANT_SECONDS) = true
getLong(INSTANT_SECONDS) = 1396331321
Exception in thread "main"
   java.time.temporal.UnsupportedTemporalTypeException:
Unsupported field: InstantSeconds
    at java.base/java.time.Instant.get(Instant.java:567)
    at InstantSecondsError.main(InstantSecondsError.java:29)

Note that the INSTANT_SECONDS value is a "long" value, you need to use getLong() method to retrieve its value. If you use the get() method, you will get an exception. Thanks to G, who pointed out this in a comment on the Web version of this book.

When running InstantSecondsError.java with JDK 1.8, I got an different exception:

herong> \progra~1\java\jdk1.8.0\bin\java InstantSecondsError
toString() = 2014-04-01T05:48:41.750Z
getEpochSecond() = 1396331321
getNano() = 750000000
isSupported(DAY_OF_WEEK) = false
isSupported(NANO_OF_SECOND) = true
get(NANO_OF_SECOND) = 750000000
isSupported(INSTANT_SECONDS) = true
getLong(INSTANT_SECONDS) = 1396331321
Exception in thread "main" java.time.DateTimeException:
 Invalid value for InstantSeconds
 (valid values -9223372036854775808 - 9223372036854775807): 1396331321
at java.time.temporal.ValueRange.checkValidIntValue(ValueRange.java...
at java.time.temporal.ChronoField.checkValidIntValue(ChronoField.java...
at java.time.Instant.get(Instant.java:569)
at InstantSecondsError.main(InstantSecondsError.java:27)

The exception message is very confusing. "(valid values -9223372036854775808 - 9223372036854775807): 1396331321" looks ok to me. The value, 1396331321, is perfectly in the range.