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I am storing two DateTimes (Joda) in an object and then I get a Period from the object by new Period(dateTime1, dateTime2). I then want to add all the periods from different objects together. I am both adding all the periods together in a variable and summing up some periods in smaller periods stored in a HashMap<long, Period>.

The result and issue is this. The first period gets "2 hours and 30 minutes" with a PeriodFormat.getDefault().print(p) (the values are the same if i concatenate getHours and getMinutes). The second value "5 hours and 52 minutes". So far so good. But when I do it with the 3rd and 4th, the minutes stop converting to hours.

"5 hours and 103 minutes"

"8 hours and 132 minutes"

It should be 10h and 12m, but as you can see. That's not what I am getting. What is the issue? How can Period just forget to do the conversion? I don't have any problems with the selected sums, yet.

code: (with variable names changed)

mainSum= new Period();
tasksSum= new HashMap<Long, Period>();
for(Entry entry: entries){
        long main_id= entry.getMain_id();
        long task_id = entry.getTask_id();
        Period entryPeriod = entry.getPeriod();

        if(main_id == mainStuff.getId()){
            mainSum = entryPeriod.plus(mainSum);
            Timber.d("mainSum: " + PeriodFormat.getDefault().print(mainSum));
            Timber.d("sum of workplace: " + mainSum.getHours() + " : " + mainSum.getMinutes());
            Period taskPeriod = tasksPeriodSums.remove(task_id);
            if(taskPeriod == null){
                tasksPeriodSums.put(task_id, entryPeriod);
            } else {
                tasksPeriodSums.put(task_id, taskPeriod.plus(entryPeriod));
            }
        }
    }

Please help, thank you :)

Yokich
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  • I got it to show the correct piece of information by adding `.normalizedStandard()` after the `plus(p)` function. So it works, but why is this neccessary? – Yokich May 29 '15 at 19:30

1 Answers1

2

This is documented behaviour, check out the Javadoc for the plus(Period) function:

/**
 * Returns a new period with the specified period added.
 * <p>
 * Each field of the period is added separately. Thus a period of
 * 2 hours 30 minutes plus 3 hours 40 minutes will produce a result
 * of 5 hours 70 minutes - see {@link #normalizedStandard()}.
 * <p>
...

Drilling down into the Javadoc of the normalizedStandard(..) function itself, we see what's the tradeoff:

/**
 * Normalizes this period using standard rules, assuming a 12 month year,
 * 7 day week, 24 hour day, 60 minute hour and 60 second minute,
 * 
...
 * However to achieve this it makes the assumption that all years are
 * 12 months, all weeks are 7 days, all days are 24 hours,
 * all hours are 60 minutes and all minutes are 60 seconds. This is not
 * true when daylight savings time is considered, and may also not be true
 * for some chronologies.
...
Barend
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