How can I get exact UTC current time stamp at time4j without usage of system timezone and system clock?

there!

I have to get the accurate current UTC time without calling a system clock or system time zone. I need to get precise UTC time via the Time4j library.

The issue that after getting UTC time via different ways there is a mismatch in accuracy with exact UTC time in particular - a mismatch in seconds. And that is critical for me.

I need to get exact UTC timestamp because of mismatch is more than 5 seconds on my machine and current UTC time. I have to transmit this timestamp into API and API in his tern updates DB. I perform some actions per seconds and real situation that I can't do this because of insufficiently accurate time.

Here some examples I've tested to get current UTC timestamp:

Moment moment = Moment.UNIX_EPOCH;

First:
PlainTimestamp test1 = SystemClock.inZonalView("UTC").now();

Second:
Moment test2 = Moment.nowInSystemTime();

Third:
PlainTimestamp test3 = moment.toLocalTimestamp();

Forth:
PlainTimestamp test4 = Moment.nowInSystemTime().toZonalTimestamp("UTC");

I didn't get needed accuracy by those methods.

Is there any methods how can I get actual UTC timestamp with very high accuracy up to seconds via time4j?

Solution

Your code examples are all finally based on System.currentTimeMillis(). If you observe low accuracy using this simple clock then you can choose between two ways:

Follow the advise of JB Nizet to regularly synchronize your OS with an NTP server
Or you can use the package net.time4j.clock which contains alternative clocks.

Example:

  SntpConnector clock = new SntpConnector("ptbtime1.ptb.de"); // ntp-server-address
  clock.connect(); // requires internet connectivity, performs the synchronization
  Moment utc = clock.currentTime()); // can be called without actual internet access