Java compute duration of Project and Tasks doesnt work

Question

I am trying to compute the duration Of each Project and each Task appointed to the Project, unfortunately it always returns 0. computeDuration:

        Date minDate = projectTasks[0].gettaskFromDate();
        Date maxDate = projectTasks[0].gettaskEndDate();
        for (int i = 0; i < numOfTasks; ++i) {
            if (projectTasks[i] != null && projectTasks[i].gettaskEndDate() != null && projectTasks[i].gettaskFromDate() != null) {
                projectTasks[i].settaskDuration(utils.Globals.computeDuration(projectTasks[i].gettaskFromDate(), projectTasks[i].gettaskEndDate()));
            }
        }
        for (int i = 0; i < numOfTasks; ++i) {
            if (projectTasks[i] != null && projectTasks[i].gettaskEndDate() != null && projectTasks[i].gettaskFromDate() != null) {
                if (utils.Globals.validateDates(projectTasks[i].gettaskFromDate(), minDate)) {
                    minDate = projectTasks[i].gettaskFromDate();
                }
                if (utils.Globals.validateDates(maxDate, projectTasks[i].gettaskEndDate())) {
                    maxDate = projectTasks[i].gettaskEndDate();
                }
            }
        }
        setprojectDuration(utils.Globals.computeDuration(minDate, maxDate));
    }

utils.Globals.validateDates:

public static boolean validateDates(Date from, Date to){
        return from.before(to);
    }

utils.Globals.computeDuration:

 public static int computeDuration(Date from, Date to){
        long diffIn = Math.abs(to.getTime() - from.getTime());
        int duration = (int) TimeUnit.DAYS.convert(diffIn, TimeUnit.MILLISECONDS);
        return duration;
    }

Thanks in advance!

Why are you using the obsolete Date class and not LocalDate? Edit your question to include a minimal reproducible example that we can copy into our IDE, compile, and run hundreds of tests to determine the cause of the problem. — Gilbert Le Blanc
– Gilbert Le Blanc, Commented Mar 31, 2023 at 11:22
Its for a project for my uni and I am obliged to use the Date format.I am well aware that LocalDate is far more useful. Also, my project uses 7 classes with each one intertwined so im having a rough time creating a minimal reproducible example. — dannyph
– dannyph, Commented Mar 31, 2023 at 11:53
@dannyph Could you please nofify your tutor that they're using an obsolete class that was supplanted a decade ago? — MC Emperor
– MC Emperor, Commented Mar 31, 2023 at 12:56
Please provide an example of Date arguments which you believe should produce a duration greater than zero days, but which are instead causing zero to be returned. — VGR
– VGR, Commented Mar 31, 2023 at 14:10
And yes, teachers requiring their students to use Date in 2023 deserve to be sacked. It’s really nothing useful to teach. — Anonymous
– Anonymous, Commented Apr 4, 2023 at 9:58

Stone · Accepted Answer · 2023-03-31 11:40:30Z

0

You could confirm if the diff between your from and to dates is over one day or not. If all diffs is less than one day, then computeDuration return 0 always.

Please check DAYS diff is expected or not in the blow codes.

 public static int computeDuration(Date from, Date to){
        long diffIn = Math.abs(to.getTime() - from.getTime());
        int duration = (int) TimeUnit.DAYS.convert(diffIn, TimeUnit.MILLISECONDS);
        return duration;
    }

answered Mar 31, 2023 at 11:40

Stone

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4 Comments

dannyph Over a year ago

I checked the given front end and i the difference between dates is always more than a day

Stone Over a year ago

Print out the from date, to dates and duration in computeDuration method. Then confirm if they are expected or not. I guess there is no magic here.

dannyph Over a year ago

Here is a part of the print: 0 EVENFLOW 490000.0 0 PENDING TaskID Title Start Date End Date Duration Status 0.1 Dynamic Maintenance of Neural Models 23/03/2023 01/11/2023 0 PENDING 0.2 Formal Verification Models 01/04/2023 29/09/2023 0 COMPLETED 1 CREXDATA 1800000.58 0 PENDING

Stone Over a year ago

I mean the parameters of method computeDuration. Anyway, try 2 numOfTasks, debug or print the intermediate variables to verify the values. BTW, Did you see any exception threw when you run your code?

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