Java Program to convert this duration to the total length in nanoseconds

With this, get the nanoseconds in days, hours and minutes. At first, set the Duration:

Duration d1 = Duration.ofDays(5);
Duration d2 = Duration.ofHours(20);
Duration d3 = Duration.ofMinutes(15);

Convert the above Duration to nanoseconds:

System.out.println("Nanoseconds in 5 days = "+d1.toNanos());
System.out.println("Nanoseconds in 20 hours = "+d2.toNanos());
System.out.println("Nanoseconds in 15 minutes = "+d3.toNanos());

Example

import java.time.Duration;
public class Demo {
   public static void main(String[] args) {
      Duration d1 = Duration.ofDays(5);
      Duration d2 = Duration.ofHours(20);
      Duration d3 = Duration.ofMinutes(15);
      System.out.println("Nanoseconds in 5 days = "+d1.toNanos());
      System.out.println("Nanoseconds in 20 hours = "+d2.toNanos());
      System.out.println("Nanoseconds in 15 minutes = "+d3.toNanos());
   }
}

Output

Nanoseconds in 5 days = 432000000000000
Nanoseconds in 20 hours = 72000000000000
Nanoseconds in 15 minutes = 900000000000