This is a working option.
public static String showDuration(LocalTime otherTime){
DateTimeFormatter df = DateTimeFormatter.ISO_LOCAL_TIME;
LocalTime now = LocalTime.now();
System.out.println("now: " + now);
System.out.println("otherTime: " + otherTime);
System.out.println("otherTime: " + otherTime.format(df));
Duration span = Duration.between(otherTime, now);
LocalTime fTime = LocalTime.ofNanoOfDay(span.toNanos());
String output = fTime.format(df);
System.out.println(output);
return output;
}
Call the method with
System.out.println(showDuration(LocalTime.of(9, 30, 0, 0)));
Produces something like:
otherTime: 09:30
otherTime: 09:30:00
11:31:27.463
11:31:27.463