How to add a long and preserve precision when printing

How do I preserve precision in my sum output. I think that what is happening is that the precision is exactly the same, but one option chooses to round.

public class Main {
    public static void main(String[] args) {
        final long seconds = 1637208584L;
        final long micro_of_second = 795307;
        final long sum = seconds + micro_of_second;
        System.out.println("seconds + micro_of_second: " + seconds + micro_of_second);
        System.out.println("sum:                       " + sum);
        System.out.println("equal?:                    " + (sum == seconds + micro_of_second));
    }
}

Output

seconds + micro_of_second: 1637208584795307
sum:                       1638003891
equal?:                    true

>Solution :

The issue here isn’t with precision its with the line

System.out.println("seconds + micro_of_second: " + seconds + micro_of_second);

this line implicitly converts seconds and micro_of_second to a string and concatenates them together.

so the result you are seeing is actually:

"seconds + micro_of_second: " + "1637208584" + "795307"

what you want to do is evaluate the integer addition before adding it to the string. you can accomplish this by changing that line to

System.out.println("seconds + micro_of_second: " + (seconds + micro_of_second));