PNS PNS - 2 years ago 131
Java Question

Java date parsing with microsecond or nanosecond accuracy

According to the SimpleDateFormat class documentation,

does not support time granularity above milliseconds in its date patterns.

So, a date string like

  • 2015-05-09 00:10:23.999750900 // The last 9 digits denote nanoseconds

when parsed via the pattern

  • yyyy-MM-dd HH:mm:ss.SSSSSSSSS // 9 'S' symbols

actually interprets the whole number after the
symbol as (nearly 1 billion!) milliseconds and not as nanoseconds, resulting in the date

  • 2015-05-20 21:52:53 UTC

i.e. over 11 days ahead. Surprisingly, using a smaller number of
symbols still results in all 9 digits being parsed (instead of, say, the leftmost 3 for

There are 2 ways to handle this issue correctly:

  • Use string preprocessing

  • Use a custom SimpleDateFormat implementation

Would there be any other way for getting a correct solution by just supplying a pattern to the standard
implementation, without any other code modifications or string manipulation?

Answer Source


No, you cannot use SimpleDateFormat to handle nanoseconds.

But your premise that…

Java does not support time granularity above milliseconds in its date patterns

…is no longer true as of Java 8.


SimpleDateFormat, and the related java.util.Date/.Calendar classes are now outmoded by the new java.time package found in Java 8 (Tutorial).

The new java.time classes support nanosecond resolution. That support includes parsing and generating nine digits of fractional second. For example, when you use the java.time.format DateTimeFormatter API, the S pattern letter denotes a "fraction of the second" rather than "milliseconds", and it can cope with nanosecond values.



The java.sql.Timestamp class also handles nanosecond resolution, but in an awkward way. Generally best to do your work inside java.time classes.

Until JDBC drivers are updated to directly support java.time data types, you can use toInstant and from methods to go back and forth between java.sql.Timestamp and java.time.

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