Can system nanoTime be negative?

You casting the difference between two long to an int . Likely, your long difference is longer than Integer. MAX_VALUE (about 2 billion) and the cast to int takes the last 32 bits, yielding a negative number. Besides, 2 billion nanoseconds is only 2 seconds, so any time longer that will overflow an int .

Is system nanoTime accurate?

Note that nanoTime can’t, by itself, have any accuracy at all, since its absolute value is arbitrary. Only the difference between successive nanoTime calls is meaningful. The (in)accuracy of that difference is in the ballpark of 1 microsecond.

What does system nanoTime do?

nanoTime() method returns the current value of the most precise available system timer, in nanoseconds. The value returned represents nanoseconds since some fixed but arbitrary time (in the future, so values may be negative) and provides nanosecond precision, but not necessarily nanosecond accuracy.

How Fast Is system nanoTime?

about 25 nanoseconds
currentTimeMillis() takes about 29 nanoseconds per call while System. nanoTime() takes about 25 nanoseconds.

Is system nanoTime unique?

No, there is no guarantee that every call to System. nanoTime() will return a unique value.

How do you convert nanoTime to milliseconds?

To convert a nanosecond measurement to a millisecond measurement, divide the time by the conversion ratio. The time in milliseconds is equal to the nanoseconds divided by 1,000,000.

What is nanoTime in Java?

nanoTime. public static long nanoTime() Returns the current value of the running Java Virtual Machine’s high-resolution time source, 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.

What is TimeUnit in Java?

A TimeUnit represents time durations at a given unit of granularity and provides utility methods to convert across units, and to perform timing and delay operations in these units.

Can we start a thread twice?

No. After starting a thread, it can never be started again. If you does so, an IllegalThreadStateException is thrown. In such case, thread will run once but for second time, it will throw exception.

Is nanotime safe to use?

So, if Holmes’s link can be read as implying that nanoTime calls clock_gettime (CLOCK_REALTIME), then it’s safe-ish as of kernel 2.6.18 on x86, and always on PowerPC (because IBM and Motorola, unlike Intel, actually know how to design microprocessors). There’s no mention of SPARC or Solaris, sadly. And of course, we have no idea what IBM JVMs do.

Can nanotime () return negative time in Java?

Many people mentioned that in Java System.nanoTime () could return negative time. I for apologize for repeating what other people already said. nanoTime () is not a clock but CPU cycle counter. Return value is divided by frequency to look like time.

How accurate is nanotime () in calculating elapsed time?

Differences in successive calls that span greater than approximately 292.3 years (2 63 nanoseconds) will not accurately compute elapsed time due to numerical overflow. It would seem that the only conclusion that can be drawn is that nanoTime () cannot be relied upon as an accurate value.

How to prevent nanotime () from returning coreid when executed?

To prevent that, you’d have to invoke a memory barrier serializing your instructions. It’d be cool if System.nanoTime () returned coreID where it executed. Show activity on this post. Java is crossplatform, and nanoTime is platform-dependent. If you use Java – when don’t use nanoTime.