How to convert nanoseconds to seconds using the TimeUnit enum?

Question

TimeUnit Enum

The following expression uses the TimeUnit enum (Java 5 and later) to convert from nanoseconds to seconds:

TimeUnit.SECONDS.convert(elapsedTime, TimeUnit.NANOSECONDS)

Well, you could just divide by 1,000,000,000:

long elapsedTime = end - start;
double seconds = (double)elapsedTime / 1_000_000_000.0;

If you use TimeUnit to convert, you'll get your result as a long, so you'll lose decimal precision but maintain whole number precision.

TimeUnit is an enum, so you can't create a new one.

The following will convert 1000000000000ns to seconds.

TimeUnit.NANOSECONDS.toSeconds(1000000000000L);

To reduce verbosity, you can use a static import:

import static java.util.concurrent.TimeUnit.NANOSECONDS;

-and henceforth just type

NANOSECONDS.toSeconds(elapsedTime);

You should write :

    long startTime = System.nanoTime();        
    long estimatedTime = System.nanoTime() - startTime;

Assigning the endTime in a variable might cause a few nanoseconds. In this approach you will get the exact elapsed time.

And then:

TimeUnit.SECONDS.convert(estimatedTime, TimeUnit.NANOSECONDS)

This will convert a time to seconds in a double format, which is more precise than an integer value:

double elapsedTimeInSeconds = TimeUnit.MILLISECONDS.convert(elapsedTime, TimeUnit.NANOSECONDS) / 1000.0;