Java-Time Clock Implementation Note

[Daniel Fuchs]

Hi Stephen,

Thanks for pointing that out.

On 16/05/2017 11:27, Stephen Colebourne wrote:
> In JDK 9, the implementation of Clock has been improved to be better
> than millisecond in most cases [1]. However, I've just noticed that
> the Javadoc of the "Implementation Note" is now wrong. It says:
>
> "The clock implementation provided here is based on
> System.currentTimeMillis(). That method provides little to no
> guarantee about the accuracy of the clock. Applications requiring a
> more accurate clock must implement this abstract class themselves
> using a different external clock, such as an NTP server."
>
> This needs to be updated to indicate that the implementation is no
> longer based on System.currentTimeMillis(). Since this is an
> "implementation note" I hope that this doesn't affect the
> specification, or need too much process.

Strictly speaking the implementation is based on the *same* clock
than System.currentTimeMillis() is based on. This is very important
as it means that times obtained by System.currentTimeMillis() and
times obtained by the system clock are consistent with each other.

So I am not sure the note [2] is actually wrong?

Would the following be a better wording (syntax/grammar may need
correction)?

<<
The clock implementation provided here is based on the same clock than 
System.currentTimeMillis() is based on, but may have a precision finer
than milliseconds if provided by the underlying clock.
However, little to no guarantee is provided about the accuracy of the 
underlying clock. Applications requiring a more accurate clock must 
implement this abstract class themselves using a different external 
clock, such as an NTP server.
 >>

best regards,

-- daniel

[2] http://download.java.net/java/jdk9/docs/api/java/time/Clock.html



>
> Is anyone willing to take this up as a JDK 9 bug?
>
> thanks
> Stephen
>
> [1] https://bugs.openjdk.java.net/browse/JDK-8068730
>