Timing how long something takes in seconds

Question

I am trying to time how long something takes and i cant get it to spit out the seconds without rounding. Here is what ive tried:

long beginTime = System.nanoTime();
//Do something
long endTime = System.nanoTime();
double time = (endTime-beginTime)/1000000000;

I've also tried using the function TimeUnit.NANOSECONDS.toSeconds and that rounds the number as well.

It should give me 1.45 seconds but it gives me 1 and it should be 1445.7191 Milliseconds but it gives me 1446.

Try dividing by `1000000000.0` instead. You are currently performing an integer division which always yields an integer as result. — luk2302, Jul 11 '16 at 19:43
I would recommend using 1e9 rather than 10000000000.0 (spot the intentional issue?) — Andy Turner, Jul 11 '16 at 19:46
@MitchWeaver but that's an integer literal, so OP would have the same issue as in the question. — Andy Turner, Jul 11 '16 at 19:56
Possible duplicate of [How can I force division to be floating point in Python?](http://stackoverflow.com/questions/1267869/how-can-i-force-division-to-be-floating-point-in-python) — xgord, Jul 11 '16 at 19:57

alexbt · Answer 1 · 2016-07-11T19:57:45.027

2

the result of your divison is implicitly casted to int, change your divisor to a double value (add a 'd' at the end): 1000000000d

long beginTime = System.nanoTime();
// Do something
long endTime = System.nanoTime();
double time = (endTime - beginTime) / 1000000000d;
System.out.println(time);

edited Jul 11 '16 at 19:57

answered Jul 11 '16 at 19:55

alexbt

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Timing how long something takes in seconds

1 Answers1