most accurate time type in java?

Question

I want to compare the performance of certain operations in my application.

Other than using the Date object, is there anything more precise?

Related: http://stackoverflow.com/questions/503877/how-can-i-measure-time-with-microsecond-precision-in-java — martin clayton, Jan 19 '10 at 21:54
Are you asking about precision or accuracy? They are not the same. — Steve Kuo, Jan 19 '10 at 22:26

score 7 · Accepted Answer · edited May 23 '17 at 12:09

7

public static long nanoTime() - Returns the current value of the most precise available system timer, in nanoseconds.

My guess is that since System.nanoTime() uses the "most precise available system timer" which apparently only has millisecond-precision on your system, you can't get anything better.

edited May 23 '17 at 12:09

Community

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answered Jan 19 '10 at 21:51

Yada

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No, it hasn't only millisecond precision. They access the much more accurate media timer in Java if possible with much more resolution. – Thorsten S. Jan 19 '10 at 21:53
Nano time is not very precise, because it's not updated every nanosecond, like @ThorstenS.mentioned, it has about a millisecond resolution. In my case, using currentTimeMillis() was better choice because nanoTime() had weird "lag spikes". – rainisr Jun 27 '19 at 07:28

score 2 · Answer 2 · answered Jan 19 '10 at 21:52

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If you're measuring elapsed time by subtracting two timestamps, you should use System.nanoTime() to get those timestamps. That's what it's for.

answered Jan 19 '10 at 21:52

Kevin Bourrillion

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Nano time is not very precise, because it's not updated every nanosecond, like @ThorstenS.mentioned, it has about a millisecond resolution. In my case, using currentTimeMillis() was better choice because nanoTime() had weird "lag spikes". – rainisr Jun 27 '19 at 07:28

score 2 · Answer 3 · answered Jan 19 '10 at 22:34

To get the CPU time you can use the getCurrentThreadCpuTime of the Thread Management Bean.
It returns the CPU time used by the actual thread in nanoseconds:

    ThreadMXBean threadMX = ManagementFactory.getThreadMXBean();
    long time = threadMX.getCurrentThreadCpuTime();

    // do something 

    time = threadMX.getCurrentThreadCpuTime() - time;  // CPU time in nanoseconds

check the documentation for details and some problems like CPU time measurement not being enabled.

most accurate time type in java?

3 Answers3