Posted By: Simucal
Accuracy Vs. Precision
What I would like to know is whether I should use System.currentTimeMillis() or System.nanoTime() when updating my object’s positions in my game? Their change in movement is directly proportional to the elapsed time since the last call and I want to be as precise as possible.
I’ve read that there are some serious time-resolution issues between different operating systems (namely that Mac / Linux have an almost 1 ms resolution while Windows has a 50ms resolution??). I’m primarly running my apps on windows and 50ms resolution seems pretty inaccurate.
Are there better options than the two I listed?
Any suggestions / comments?
If you’re just looking for extremely precise measurements of elapsed time, use
System.currentTimeMillis() will give you the most accurate possible elapsed time in milliseconds since the epoch, but
System.nanoTime() gives you a nanosecond-precise time, relative to some arbitrary point.
From the Java Documentation:
public static long nanoTime()
Returns the current value of the most precise available system timer, in nanoseconds.
This method can only be used to
measure elapsed time and is not
related to any other notion of system
or wall-clock time. The value returned
represents nanoseconds since some
fixed but arbitrary origin time (perhaps in
the future, so values may be
negative). This method provides
nanosecond precision, but not
necessarily nanosecond accuracy. No
guarantees are made about how
frequently values change. Differences
in successive calls that span greater
than approximately 292 years (263
nanoseconds) will not accurately
compute elapsed time due to numerical
For example, to measure how long some code takes to execute:
long startTime = System.nanoTime(); // ... the code being measured ... long estimatedTime = System.nanoTime() - startTime;