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Editorial Team
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Asked: 2026-05-13T10:35:24+00:00

I would like to measure elapsed time in a Java. However differences in System.currentTimeMillis()

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I would like to measure elapsed time in a Java. However differences in System.currentTimeMillis() and (I believe) System.nanoTime() can be changed by external changes eg someone (or the system) altering the system clock.

Using network calls is not an option as it’s possible very frequent and fast returns are required.

Is there a common solution for this?

EDIT

Sorry, I should have elaborated about the reason. It isn’t to stop malicious users – it’s things like client initiated logout for being idle and routine client events.

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1 Answer

  1. Editorial Team

    This doesn’t really answer your question, but bug #6458294 implies that where possible, Sun’s implementation of nanoTime() will use mechanisms which are truly monotonic (CLOCK_MONOTONIC on Linux, QueryPerformanceFrequency/QueryPerformanceCounter on Windows). Only if these are unavailable will it fall back to a mechanism which is susceptible to system clock changes.

    If you have control (or at least knowledge) of the hardware you’re running on, and can ensure that these clock mechanisms will be available, you might be in luck and nanoTime() will do fine.

    You may also like to read this blog post, which discusses the HotSpot-on-Windows case in more detail.

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