java calculate pregnancy algorithm

Question

hello I am trying to calculate how many days are left in a pregnancy term but I think my algorithm is incorrect

public int getDaysPregnantRemainder_new() {
    GregorianCalendar calendar = new GregorianCalendar();
   calendar.set(Calendar.HOUR_OF_DAY, 0);
  calendar.set(Calendar.MINUTE, 0);
   calendar.set(Calendar.SECOND, 0);
   long diffDays = 280 - ((getDueDate().getTime() - calendar.getTime()
  .getTime()) / (24 * 60 * 60 * 1000));
  return (int) Math.abs((diffDays) % 7);
   }

I am basing it off of a 280 day term, getDueDate() is a Date object and getTime() returns millisecond unix time

On some real world days the number reported is off by one, sometimes, and I am starting to think my algorithm is just wrong, or the millisecond time get gradually further and further off, or the millisecond time is not precise enough, or the gregorian calendar function rounds weird.

All in all I'm not sure, any insight appreciated

Take a look at [Joda-Time](http://joda-time.sourceforge.net/) — MadProgrammer, May 21 '13 at 04:09
presumably its off by one when the time portion is over/under the 12 hour mark....Strip off the time portion of the date... — Mitch Wheat, May 21 '13 at 04:09

score 5 · Accepted Answer · answered May 21 '13 at 04:18

5

I don't know about your algorithm, but this (is basically) the one I used while tracking my wife's pregency...nerds...

Save yourself a lot of "guess" work and get hold of Joda-Time

public class TestDueDate {

    public static final int WEEKS_IN_PREGNANCY = 40;
    public static final int DAYS_IN_PREGNANCY = WEEKS_IN_PREGNANCY * 7;

    public static void main(String[] args) {

        DateTime dueDate = new DateTime();
        dueDate = dueDate.plusDays(DAYS_IN_PREGNANCY);

        System.out.println("dueDate = " + dueDate);

        DateTime today = DateTime.now();

        Days d = Days.daysBetween(today, dueDate);

        int daysRemaining = d.getDays();

        int daysIn = DAYS_IN_PREGNANCY - daysRemaining;

        int weekValue = daysIn / 7;
        int weekPart = daysIn % 7;

        String week = weekValue + "." + weekPart;

        System.out.println("Days remaining = " + daysRemaining);
        System.out.println("Days In = " + daysIn);
        System.out.println("Week = " + week);

    }
}

This will output...

dueDate = 2014-02-25T14:14:31.159+11:00
Days remaining = 279
Days In = 1
Week = 0.1

answered May 21 '13 at 04:18

MadProgrammer

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joda-time did the trick – CQM May 22 '13 at 17:17
The major problem with your original approach is it won't take into account things like leap years and seconds and the strange issues over certain century boundaries – MadProgrammer May 22 '13 at 20:18
What should i do if i have to calculate due date according to cycles? – Abdullah Programmer Oct 14 '22 at 04:20
@AbdullahProgrammer Start by taking a look at the [Date/Time](https://docs.oracle.com/javase/tutorial/datetime/index.html) APIs introduced in Java 8 – MadProgrammer Oct 14 '22 at 06:20
I am saying that "What formula will be used for finding pregnancy due date with custom cycle average periods"? – Abdullah Programmer Oct 15 '22 at 07:11
@AbdullahProgrammer Off the top my head, I have no idea – MadProgrammer Oct 15 '22 at 21:21

java calculate pregnancy algorithm

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