Calculating time difference in Milliseconds

Question

I am making a call to a method by passing ipAddress and it will return back the location of ipAddress like Country, City, etc etc. So I was trying to see how much time it is

Answer 1

In the old days (you know, anytime before yesterday) a PC's BIOS timer would "tick" at a certain interval. That interval would be on the order of 12 milliseconds. Thus, it's quite easy to perform two consecutive calls to get the time and have them return a difference of zero. This only means that the timer didn't "tick" between your two calls. Try getting the time in a loop and displaying the values to the console. If your PC and display are fast enough, you'll see that time jumps, making it look as though it's quantized! (Einstein would be upset!) Newer PCs also have a high resolution timer. I'd imagine that nanoTime() uses the high resolution timer.

Answer 2

Since Java 1.5, you can get a more precise time value with System.nanoTime(), which obviously returns nanoseconds instead.

There is probably some caching going on in the instances when you get an immediate result.

Answer 3

From Java 8 onward you can try the following:

import java.time.*;
import java.time.temporal.ChronoUnit;

Instant start_time = Instant.now();
// Your code
Instant stop_time = Instant.now();

System.out.println(Duration.between(start_time, stop_time).toMillis());

//or

System.out.println(ChronoUnit.MILLIS.between(start_time, stop_time));

Answer 4

In such a small cases where difference is less than 0 milliseconds you can get difference in nano seconds as well.

System.nanoTime()

Answer 5

Try this

long start_time = System.nanoTime();
resp = GeoLocationService.getLocationByIp(ipAddress);
long end_time = System.nanoTime();
double difference = (end_time - start_time) / 1e6;

Answer 6

I pretty much like the (relatively) new java.time library: it's close to awesome, imho.

You can calculate a duration between two instants this way:

import java.time.*

Instant before = Instant.now();
// do stuff
Instant after = Instant.now();
long delta = Duration.between(before, after).toMillis(); // .toWhatsoever()

API is awesome, highly readable and intuitive.

Classes are thread-safe too. !

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References: Oracle Tutorial, Java Magazine