Java: Converting an input of seconds into hours/mi

Question

This is an exercise question taken from Java Software Solutions: foundations of program design by Lewis & Loftus, 4th edition ; Question PP2.6 (here is a link)

Question is as follows: " Create a project that reads a value representing a number of seconds, then print the equivalent amount of time as a combination of hours, minutes, and seconds. (For example, 9999 seconds is equivalent to 2 hours, 46 minutes, and 39 seconds.)"

I have so far tried the following

public static void main(String[] args)
{
    Scanner scan = new Scanner(System.in);

    double totalSecs, seconds, minutes, hours;

    System.out.println("Enter number of seconds: ");

    totalSecs = scan.nextInt();

    hours = totalSecs/3600;
    minutes = (Math.abs(Math.round(hours)-hours))*60;
    seconds = (Math.abs(Math.round(minutes)-minutes))*60;

    System.out.print(hours + "\n" + minutes + "\n" + seconds);

}

Answer came out to, hours: 2.7775 minutes: 13.350000000000009 seconds: 21.00000000000051

What I want to do is take the decimals of, say, hours and multiply them by 60 to get minutes and repeat the process for seconds. I'm however having trouble figuring it out, hence the messy solution of (Math.abs) etc.

What would you recommend me to change/add? Thanks!

Note: This is a book for beginners, hence I've not learned many more operations than those I've already stated in the code. As such, I haven't understood the solution for the previous times this question has been asked.

Answer 1

As an alternative of user2004685's answer;

int seconds = 9999; 
int hour = 9999 / (60 * 60); //int variables holds only integer so hour will be 2
seconds = 9999 % (60 * 60); // use modulo to take seconds without hours so it will be 2799
int minute = seconds / 60; //same as int variable so minute will be 49
seconds = seconds % 60; // modulo again to take only seconds
System.out.println(hour + ":" + minute + ":" + seconds);

Answer 2

Here is a much simpler way of doing it:

public static void main (String[] args) throws Exception {
    SimpleDateFormat sf = new SimpleDateFormat("HH:mm:ss");
    TimeZone.setDefault(TimeZone.getTimeZone("GMT"));
    System.out.println(sf.format(new Date(9999000)));
}

Note: Please note that this will only show the output in 24-hour format and if number of hours is greater than 24 then it'll increment a day and will start over. For example, 30 hours will be displayed as 06:xx:xx. Also, you'll have to pass the input in milliseconds instead of seconds.

If you want to do it your way then you should probably do something like this:

public static void main (String[] args) throws Exception {
    long input = 9999;
    long hours = (input - input%3600)/3600;
    long minutes = (input%3600 - input%3600%60)/60;
    long seconds = input%3600%60;
    System.out.println("Hours: " + hours + " Minutes: " + minutes + " Seconds: " + seconds);
}

Output:

Hours: 2 Minutes: 46 Seconds: 39