I´m searching for a way to calculate the number of business days in Joda Time. The overall number of days i get with:
DateMidnight start = new DateMidnight(DateMidnight.now());
DateMidnight end = new DateMidnight(2014,10,10);
int days = Days.daysBetween(start,end).getDays();
Then i would subtract the number of weekend-/holidaydays. But how do i calculate them?
Would be glad about help.
Had to figure this out today and didn't like any of the answers I saw online. So here's my solution for anyone else who comes across this. Note that I assume that if start or end is on a weekend, I make it the next business day (Sat or Sun becomes the following Monday). After that its as simple as getting the number of days between, then figuring out the number of weekends between, and finally subtracting 2 days for every weekend there is:
public class DateUtil {
public static final int DAYS_PER_WEEKEND = 2;
public static final int WEEK_START = DateTimeConstants.MONDAY;
public static final int WEEK_END = DateTimeConstants.FRIDAY;
public static int workdayDiff(Date d1, Date d2) {
LocalDate start = LocalDate.fromDateFields(d1);
LocalDate end = LocalDate.fromDateFields(d2);
start = toWorkday(start);
end = toWorkday(end);
int daysBetween = Days.daysBetween(start, end).getDays();
int weekendsBetween = Weeks.weeksBetween(start.withDayOfWeek(WEEK_START), end.withDayOfWeek(WEEK_START)).getWeeks();
return daysBetween - (weekendsBetween * DAYS_PER_WEEKEND);
}
public static LocalDate toWorkday(LocalDate d) {
if (d.getDayOfWeek() > WEEK_END) {
return d.plusDays(DateTimeConstants.DAYS_PER_WEEK - d.getDayOfWeek() + 1);
}
return d;
}
}
I'm sure someone will come along and comment that not everyone has the same weekends blah blah blah. I leave locale differences as an exercise for those who do :)
The Joda-Time library is now in maintenance-mode, and advises migration to java.time classes as seen in this impractical example:
EnumSet // An implementation of `Set` highly optimized in both performance and memory-usage for a collection of enum objects.
.of( DayOfWeek.SATURDAY , DayOfWeek.SUNDAY ) // Using enum `DayOfWeek` defining 7 objects, one for each day-of-week.
.contains( // Search `Set` for a match.
LocalDate // The `java.time.LocalDate` class represents a date-only without time-of-day and without time zone.
.of( 2018 , Month.MARCH , 23 ) // Specify month by `Month` enum or by number 1-12 for Jan-Dec.
.getDayOfWeek() // Return a `DayOfWeek` object for this date’s day-of-week.
) // Returns a `boolean`, true if value found in set.
The modern approach uses the java.time classes that supplanted the excellent Joda-Time library.
LocalDateThe LocalDate class represents a date-only value without time-of-day and without time zone.
A time zone is crucial in determining a date. For any given moment, the date varies around the globe by zone. For example, a few minutes after midnight in Paris France is a new day while still “yesterday” in Montréal Québec.
If no time zone is specified, the JVM implicitly applies its current default time zone. That default may change at any moment during runtime(!), so your results may vary. Better to specify your [desired/expected time zone][2] explicitly as an argument.
Specify a proper time zone name in the format of continent/region, such as America/Montreal, Africa/Casablanca, or Pacific/Auckland. Never use the 3-4 letter abbreviation such as EST or IST as they are not true time zones, not standardized, and not even unique(!).
ZoneId z = ZoneId.of( "America/Montreal" ) ;
LocalDate today = LocalDate.now( z ) ;
If you want to use the JVM’s current default time zone, ask for it and pass as an argument. If omitted, the JVM’s current default is applied implicitly. Better to be explicit, as the default may be changed at any moment during runtime by any code in any thread of any app within the JVM.
ZoneId z = ZoneId.systemDefault() ; // Get JVM’s current default time zone.
Or specify a date. You may set the month by a number, with sane numbering 1-12 for January-December.
LocalDate ld = LocalDate.of( 1986 , 2 , 23 ) ; // Years use sane direct numbering (1986 means year 1986). Months use sane numbering, 1-12 for January-December.
Or, better, use the Month enum objects pre-defined, one for each month of the year. Tip: Use these Month objects throughout your codebase rather than a mere integer number to make your code more self-documenting, ensure valid values, and provide type-safety.
LocalDate ld = LocalDate.of( 1986 , Month.FEBRUARY , 23 ) ;
You want to count days elapsed while skipping weekends (Saturday/Sunday) and holidays. Let's start with the weekends.
Define a Set of day-of-week values to define the weekend. Use the DayOfWeek enum that predefines seven objects, one for each day of the week.
Set< DayOfWeek > weekend = EnumSet.of( DayOfWeek.SATURDAY , DayOfWeek.SUNDAY ) ;
Initialize a collection for the hit dates. Set the initial capacity as a way to slightly optimize handling of ArrayList.
int initialCapacity = ChronoUnit.DAYS.between( start , stop ) ; // Bigger than we need, but better than too small.
ArrayList< LocalDate > dates = new ArrayList<>( initialCapacity ) ;
Loop dates, incrementing day by day.
LocalDate ld = start ;
while ( ld.isBefore( stop ) ) {
boolean hit = ( ! weekend.contains( ld.getDayOfWeek() ) ) ;
if( hit ) {
dates.add( ld ) ;
}
}
Free up a bit of memory by trimming empty slots from our List.
dates.trimToSize() ;
Lastly, query the List for its size to get our number of days elapsed.
int weekdaysElapsed = dates.size() ;
As for holidays, you are own your own. The definition of holidays varies far too much to automate.
There are some data files and services that provide lists of holidays by country. But you are responsible for finding the appropriate one for your country, state/province, town, industry, and company. And you must regularly check that it is correct and updated.
Even with a data source, you will likely need to customize the provided list to omit or add various holidays. For example, in the US, not all businesses respect all Federally-designated holidays, and likewise, many businesses define additional holidays not recognized by the state or federal governments.
In the end, I suggest you are best off by creating a database or other data source of your own which you periodically update manually with the particular holidays of interest to you. Add code to that seen above to add another criterion to boolean hit, testing each date against your own list of holidays such as List::contains.
The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.
The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
You may exchange java.time objects directly with your database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.
The answer from DeezCashews worked well for me, with the following optional modification...
If like me you are looking for the inclusive difference between the dates rather than the exclusive difference between the dates (eg an employee holiday request from Mon 21st Nov to Fri 25th Nov should come out at 5 days rather than 4), then the correct approach is to add a day to the "end" date before calling the "toWorkday()" method. Augementing the difference at any point after this does not work due to the way the algorithm is implemented
