A duration is given.
Ex: Jan 15-March 15
I want to count the number of days which belongs to each month, in that given duration.
In this example,
number of days of January in that duration; 15
number of days of February in that duration; 28
number of days of March in that duration; 15
I'm looking for a solution other that traversing through each date of the duration and checking if Date.getMonth() = "Month I want to check against"
Is there an easier way of doing this using methods in Java Date or Java SQL Date or using any other Date type?
Map < YearMonth , Long > with lambda syntax
Here is a solution using a bit of terse code using streams and lambdas. While this solution does traverse each date of the time range, the simplicity and clarity of the code may outweigh that inefficiency.
Use LocalDate for the starting and stopping date. Use YearMonth to track each month.
LocalDate start = LocalDate.of( 2019 , 1 , 15 );
LocalDate stop = LocalDate.of( 2019 , 3 , 16 );
Make a Map to keep a number of days for each month.
Map < YearMonth, Long > map =
start
.datesUntil( stop )
.collect(
Collectors.groupingBy(
( LocalDate localDate ) -> YearMonth.from( localDate ) ,
TreeMap::new ,
Collectors.counting()
)
);
Dump to console.
{2019-01=17, 2019-02=28, 2019-03=15}
System.out.println( map );
Given a starting date, LocalDate::datesUntil provides a Stream of LocalDate objects, incremented by days.
Then just do a grouping into a SortedMap (a TreeMap) to keep months in chronological order, classified by the YearMonth and counting the days for that month in the range.
If you want the total days you can just do
long totalDays = d.datesUntil(LocalDate.of(2019, 3, 16)).count();
This is just a simple example I threw together with some basic research.
LocalDate from = LocalDate.of(2019, Month.JANUARY, 15);
LocalDate to = LocalDate.of(2019, Month.MARCH, 15);
DateTimeFormatter monthFormatter = DateTimeFormatter.ofPattern("MMM");
LocalDate date = from;
while (date.isBefore(to)) {
LocalDate endOfMonth = date.withDayOfMonth(date.lengthOfMonth());
if (endOfMonth.isAfter(to)) {
endOfMonth = to;
}
// Inclusive to exclusive comparison
long days = ChronoUnit.DAYS.between(date, endOfMonth.plusDays(1));
System.out.println(days + " days in " + date.format(monthFormatter));
date = date.plusMonths(1).withDayOfMonth(1);
}
This will output
17 days in Jan.
28 days in Feb.
15 days in Mar.
There are probably better ways to achieve the same result, but as I said, I just threw it together with a little bit of Googling and trial and error.
As has already been stated, you should avoid using the older, out-of-date and effectively deprecated Date, Calendar and associated classes.
Try this. May be something like this you want. So it set a startdate and enddate, then loop for each moth till the end date and calculate the day count. I have not tested it thoroughly, but should be close to your concept.
public static void main(String[] args) throws ParseException {
String startDateS = "01/15/2019";
String endDateS = "03/15/2019";
SimpleDateFormat dateFormat = new SimpleDateFormat("MM/dd/yyyy");
Date startDate = dateFormat.parse(startDateS);
Date endDate = dateFormat.parse(endDateS);
while (endDate.compareTo(startDate) > 0) {
Calendar c = Calendar.getInstance();
c.setTime(startDate);
c.set(Calendar.DAY_OF_MONTH, c.getActualMaximum(Calendar.DAY_OF_MONTH));
Date endOfMonth = c.getTime();
if( endDate.compareTo(endOfMonth) > 0 )
System.out.println("Count Month " + getMonthForInt(c.get(Calendar.MONTH)) + " " + getDifferenceDays(startDate, endOfMonth));
else
System.out.println("Count Month " + getMonthForInt(c.get(Calendar.MONTH)) + " " + getDifferenceDays(startDate, endDate));
c.add(Calendar.DAY_OF_MONTH, 1);
startDate = c.getTime();
}
}
static String getMonthForInt(int num) {
String month = "wrong";
DateFormatSymbols dfs = new DateFormatSymbols();
String[] months = dfs.getMonths();
if (num >= 0 && num <= 11) {
month = months[num];
}
return month;
}
public static int getDifferenceDays(Date d1, Date d2) {
int daysdiff = 0;
long diff = d2.getTime() - d1.getTime();
long diffDays = diff / (24 * 60 * 60 * 1000) + 1;
daysdiff = (int) diffDays;
return daysdiff;
}
You can do the same using Java.time in Java 8.
public static void main(String[] args) throws ParseException {
String startDateS = "01/15/2019";
String endDateS = "03/15/2019";
DateTimeFormatter format1 = DateTimeFormatter.ofPattern("MM/dd/yyyy");
LocalDate startDate = LocalDate.parse(startDateS, format1);
LocalDate endDate = LocalDate.parse(endDateS, format1);
while (endDate.compareTo(startDate) > 0) {
LocalDate endOfMonth = startDate.minusDays(startDate.getDayOfMonth()).plusMonths(1);
if( endDate.compareTo(endOfMonth) > 0 )
System.out.println("Count Month " + getMonthForInt(startDate) + " " + getDifferenceDays(startDate, endOfMonth));
else
System.out.println("Count Month " + getMonthForInt(startDate) + " " + getDifferenceDays(startDate, endDate));
startDate = endOfMonth.plusDays(1);
}
}
static String getMonthForInt(LocalDate startDate) {
return startDate.getMonth().getDisplayName(
TextStyle.FULL ,
Locale.US
);
}
public static long getDifferenceDays(LocalDate d1, LocalDate d2) {
// return Duration.between(d2.atStartOfDay(), d1.atStartOfDay()).toDays();
return ChronoUnit.DAYS.between(d1, d2) + 1;
}
Let's say I have two datetimes, 30-11-2015 10:00 and 02-12-2015 15:00. I also have two times, 07:00 and 22:00. How could I calculate the amount of time passed between the two date/times that was within the second times? Using Calendar object? It seems simple but its boggling my mind.
Since none of the other answers include runnable code, I can't tell if they solve the problem or not.
To calculate the duration of a time range within a date range, you have to:
Split the date range into multiple date ranges, each spanning no more than one day.
Calculate the time range within each day date range
Taking the example date range from the question. 30-11-2015 10:00 and 02-12-2015 15:00, we generate the following split day date ranges:
30-11-2015 10:00 - 30-11-2015 24:00
01-12-2015 00:00 - 01-12-2015 24:00
02-12-2015 00:00 - 02-12-2015 15:00
Now, we can apply the time range of 7:00 - 22:00 to each of the split day date ranges.
30-11-2015 10:00 - 30-11-2015 24:00 -> 12 hours
01-12-2015 00:00 - 01-12-2015 24:00 -> 15 hours
02-12-2015 00:00 - 02-12-2015 15:00 -> 8 hours
For a total of 35 hours. The actual calculation would probably be in minutes instead of hours.
Edited to add: I created a Time and a TimeRange class to hold the time and a day time range, respectively. I used the java.util.Date, although I had to create my own increment a day method.
I put all of the classes together so I could post this easier. The classes should be put in separate files.
package com.ggl.testing;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class TimeRangeTest {
private static final SimpleDateFormat inputDateFormat = new SimpleDateFormat(
"dd-MM-yyyy");
public static void main(String[] args) {
TimeRangeTest test = new TimeRangeTest();
int minutes = test.calculateTotalMinutes("30-11-2015 10:00",
"02-12-2015 15:00", "07:00", "22:00");
System.out.println(minutes + " minutes, " + (minutes / 60) + " hours");
}
public int calculateTotalMinutes(String startDateTimeString,
String endDateTimeString, String startTimeString,
String endTimeString) {
try {
List<TimeRange> timeRanges = generateTimeRanges(
startDateTimeString, endDateTimeString);
return calculateTimeRange(timeRanges, startTimeString,
endTimeString);
} catch (ParseException e) {
e.printStackTrace();
return 0;
}
}
private List<TimeRange> generateTimeRanges(String startDateTimeString,
String endDateTimeString) throws ParseException {
Date startDate = inputDateFormat.parse(startDateTimeString.substring(0,
10));
Time startTime = new Time(startDateTimeString.substring(11));
Date endDate = inputDateFormat
.parse(endDateTimeString.substring(0, 10));
Time endTime = new Time(endDateTimeString.substring(11));
List<TimeRange> timeRanges = new ArrayList<>();
Date currentDate = new Date(startDate.getTime());
Time currentTime = new Time(startTime);
Time eodTime = new Time("24:00");
while (currentDate.compareTo(endDate) < 0) {
TimeRange timeRange = new TimeRange(currentDate, currentTime,
eodTime);
timeRanges.add(timeRange);
currentTime = new Time("00:00");
currentDate = new Date(currentDate.getTime() + 24L * 60L * 60L
* 1000L);
}
TimeRange timeRange = new TimeRange(currentDate, currentTime, endTime);
timeRanges.add(timeRange);
return timeRanges;
}
private int calculateTimeRange(List<TimeRange> timeRanges,
String startTimeString, String endTimeString) {
int count = 0;
Time startTime = new Time(startTimeString);
Time endTime = new Time(endTimeString);
for (TimeRange timeRange : timeRanges) {
Time sodTime = new Time(timeRange.getStartTime());
Time eodTime = new Time(timeRange.getEndTime());
Time sTime = startTime.max(sodTime);
Time eTime = endTime.min(eodTime);
count += eTime.difference(sTime);
}
return count;
}
public class TimeRange {
private final SimpleDateFormat inputDateFormat = new SimpleDateFormat(
"dd-MM-yyyy");
private final Date date;
private final Time startTime;
private final Time endTime;
public TimeRange(Date date, Time startTime, Time endTime) {
this.date = date;
this.startTime = startTime;
this.endTime = endTime;
}
public Date getDate() {
return date;
}
public Time getStartTime() {
return startTime;
}
public Time getEndTime() {
return endTime;
}
#Override
public String toString() {
return inputDateFormat.format(getDate()) + " "
+ startTime.toString() + " -> " + endTime.toString();
}
}
public class Time {
private final int minutesPastMidnight;
public Time(String timeString) {
int hours = Integer.valueOf(timeString.substring(0, 2));
int minutes = Integer.valueOf(timeString.substring(3, 5));
this.minutesPastMidnight = hours * 60 + minutes;
}
public Time(Time time) {
this.minutesPastMidnight = time.getMinutesPastMidnight();
}
private int getMinutesPastMidnight() {
return minutesPastMidnight;
}
public int difference(Time time) {
return this.getMinutesPastMidnight()
- time.getMinutesPastMidnight();
}
public Time min(Time time) {
return (difference(time) > 0) ? time : this;
}
public Time max(Time time) {
return (difference(time) > 0) ? this : time;
}
#Override
public String toString() {
int hours = minutesPastMidnight / 60;
int minutes = minutesPastMidnight - (hours * 60);
return String.format("%02d:%02d", hours, minutes);
}
}
}
If you use java8, you can use LocalDateTime. Then your code could looks like this:
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm");
LocalDateTime dateTimeStart = LocalDateTime.parse("2015-10-01 10:00", formatter);
LocalDateTime dateTimeEnd = LocalDateTime.parse("2015-10-02 10:00", formatter);
long seconds = Duration.between(dateTimeStart, dateTimeEnd).getSeconds();
Or LocalTime if you have only time. Then it could looks like this:
LocalTime timeStart = LocalTime.parse("07:00");
LocalTime timeEnd = LocalTime.parse("22:00");
long seconds = Duration.between(timeStart, timeEnd).getSeconds();
If you can't use java8, you can get the number of milliseconds since 1970-01-01 00:00:00 to your date using getTime() method and do simple subtraction operation, like this:
SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm");
Date dateStart = simpleDateFormat.parse("2015-10-01 10:00");
Date dateEnd = simpleDateFormat.parse("2015-10-02 10:00");
long milliseconds = dateEnd.getTime() - dateStart.getTime();
long seconds = resultInMillisecond / 1000;
Can anyone point me to some Java snippet wherein i can get business (except Sat and Sun) days between two dates.
public static int getWorkingDaysBetweenTwoDates(Date startDate, Date endDate) {
Calendar startCal = Calendar.getInstance();
startCal.setTime(startDate);
Calendar endCal = Calendar.getInstance();
endCal.setTime(endDate);
int workDays = 0;
//Return 0 if start and end are the same
if (startCal.getTimeInMillis() == endCal.getTimeInMillis()) {
return 0;
}
if (startCal.getTimeInMillis() > endCal.getTimeInMillis()) {
startCal.setTime(endDate);
endCal.setTime(startDate);
}
do {
//excluding start date
startCal.add(Calendar.DAY_OF_MONTH, 1);
if (startCal.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY && startCal.get(Calendar.DAY_OF_WEEK) != Calendar.SUNDAY) {
++workDays;
}
} while (startCal.getTimeInMillis() < endCal.getTimeInMillis()); //excluding end date
return workDays;
}
Start date and end date are exclusive, Only the days between given
dates will be counted. Start date and end date will not be included.
Solution without loop:
static long days(Date start, Date end){
//Ignore argument check
Calendar c1 = Calendar.getInstance();
c1.setTime(start);
int w1 = c1.get(Calendar.DAY_OF_WEEK);
c1.add(Calendar.DAY_OF_WEEK, -w1);
Calendar c2 = Calendar.getInstance();
c2.setTime(end);
int w2 = c2.get(Calendar.DAY_OF_WEEK);
c2.add(Calendar.DAY_OF_WEEK, -w2);
//end Saturday to start Saturday
long days = (c2.getTimeInMillis()-c1.getTimeInMillis())/(1000*60*60*24);
long daysWithoutWeekendDays = days-(days*2/7);
// Adjust days to add on (w2) and days to subtract (w1) so that Saturday
// and Sunday are not included
if (w1 == Calendar.SUNDAY && w2 != Calendar.SATURDAY) {
w1 = Calendar.MONDAY;
} else if (w1 == Calendar.SATURDAY && w2 != Calendar.SUNDAY) {
w1 = Calendar.FRIDAY;
}
if (w2 == Calendar.SUNDAY) {
w2 = Calendar.MONDAY;
} else if (w2 == Calendar.SATURDAY) {
w2 = Calendar.FRIDAY;
}
return daysWithoutWeekendDays-w1+w2;
}
Solution without loop in 5 lines of code
Days between are defined in the same way as ChronoUnit.DAYS.between(start, end) which means there are 4 days between Monday and Friday. Since we are only interested in weekdays we have to subtract weekends, therefore from Friday until Tuesday there will be 2 weekdays(just compute endDay - startDay and subtract 2 for the weekend). Add 1 to the result if you want an inclusive result, i.e. not days between.
I present two solutions.
First solution (5-liner, short and cryptic):
import java.time.*;
import java.time.temporal.*;
public static long calcWeekDays1(final LocalDate start, final LocalDate end) {
final DayOfWeek startW = start.getDayOfWeek();
final DayOfWeek endW = end.getDayOfWeek();
final long days = ChronoUnit.DAYS.between(start, end);
final long daysWithoutWeekends = days - 2 * ((days + startW.getValue())/7);
//adjust for starting and ending on a Sunday:
return daysWithoutWeekends + (startW == DayOfWeek.SUNDAY ? 1 : 0) + (endW == DayOfWeek.SUNDAY ? 1 : 0);
}
Second solution:
public static long calcWeekDays2(final LocalDate start, final LocalDate end) {
final int startW = start.getDayOfWeek().getValue();
final int endW = end.getDayOfWeek().getValue();
final long days = ChronoUnit.DAYS.between(start, end);
long result = days - 2*(days/7); //remove weekends
if (days % 7 != 0) { //deal with the rest days
if (startW == 7) {
result -= 1;
} else if (endW == 7) { //they can't both be Sunday, otherwise rest would be zero
result -= 1;
} else if (endW < startW) { //another weekend is included
result -= 2;
}
}
return result;
}
java.time
The modern way is with the java.time classes.
LocalDate
The LocalDate class represents a date-only value without time-of-day and without time zone.
LocalDate start = LocalDate.of( 2016 , 1 , 23 );
LocalDate stop = start.plusMonths( 1 );
DayOfWeek enum
The DayOfWeek enum provides a singleton instance for each of the sever days of the week.
DayOfWeek dow = start.getDayOfWeek();
if( dow.equals( DayOfWeek.SATURDAY ) || dow.equals( DayOfWeek.SUNDAY ) ) …
We can collect the desired dates in a List.
int initialCapacity = Duration.between( start , stop ).toDays() ;
List<LocalDate> dates = new ArrayList<>( initialCapacity );
…
if( dow.equals( DayOfWeek.SATURDAY ) || dow.equals( DayOfWeek.SUNDAY ) ) {
dates.add( date );
…
An EnumSet is an extremely efficient, fast and low-memory, implementation of Set. We can use an EnumSet instead of the if statement seen above.
Set<DayOfWeek> weekend = EnumSet.of( DayOfWeek.SATURDAY , DayOfWeek.SUNDAY ) ;
…
if( weekend.contains( dayOfWeek ) ) …
Put that all together.
LocalDate date = start ;
while( date.isBefore( stop ) ) {
if( ! weekend.contains( date.getDayOfWeek() ) ) { // If not weekend, collect this LocalDate.
dates.add( date ) ;
}
// Prepare for next loop.
date = date.plusDays( 1 ); // Increment to next day.
}
nextWorkingDay TemporalAdjuster
Another approach uses the ThreeTen-Extra project to add classes that work with java.time.
The Temporals class adds additional implementations of TemporalAdjuster for manipulating date-time values. We want the nextWorkingDay adjuster to increment the date while skipping over Saturday & Sunday.
LocalDate start = LocalDate.of( 2016 , 1 , 23 );
LocalDate stop = start.plusMonths( 1 );
int initialCapacity = Duration.between( start , stop ).toDays() ;
List<LocalDate> dates = new ArrayList<>( initialCapacity );
LocalDate date = start.minusDays( 1 ); // Start a day ahead.
while( date.isBefore( stop ) ) {
date = date.with( org.threeten.extra.Temporals.nextWorkingDay() );
// Double-check ending date as the `nextWorkingDay` adjuster could move us past the stop date.
if( date.isBefore( stop ) ) {
dates.add( date ) ;
}
}
Performance
I am curious about the performance of the various approach in various Answers on this page. I am considering only the modern java.time code, not the code using troublesome legacy Date/Calendar classes.
Here are four methods that each return the number of days elapsed.
One uses the clever math-based approach seen in the Answer by Roland.
private long countWeekDaysMath ( LocalDate start , LocalDate stop ) {
// Code taken from Answer by Roland.
// https://stackoverflow.com/a/44942039/642706
long count = 0;
final DayOfWeek startW = start.getDayOfWeek();
final DayOfWeek stopW = stop.getDayOfWeek();
final long days = ChronoUnit.DAYS.between( start , stop );
final long daysWithoutWeekends = days - 2 * ( ( days + startW.getValue() ) / 7 );
//adjust for starting and ending on a Sunday:
count = daysWithoutWeekends + ( startW == DayOfWeek.SUNDAY ? 1 : 0 ) + ( stopW == DayOfWeek.SUNDAY ? 1 : 0 );
return count;
}
Two use approaches seen in this Answer of mine: (a) Visit each date, incrementing one-by-one in a conventional loop.
private long countWeekDaysVisit ( LocalDate start , LocalDate stop ) {
// Code taken from Answer by Basil Bourque.
// https://stackoverflow.com/a/40369140/642706
long count = 0;
Set < DayOfWeek > weekend = EnumSet.of( DayOfWeek.SATURDAY , DayOfWeek.SUNDAY );
LocalDate ld = start;
while ( ld.isBefore( stop ) ) {
if ( ! weekend.contains( ld.getDayOfWeek() ) ) { // If not weekend, collect this LocalDate.
count++;
}
// Prepare for next loop.
ld = ld.plusDays( 1 ); // Increment to next day.
}
return count;
}
…and, (b) Using the TemporalAdjuster implementation org.threeten.extra.Temporals.nextWorkingDay().
private long countWeekDaysAdjuster ( LocalDate start , LocalDate stop ) {
// Code taken from Answer by Basil Bourque.
// https://stackoverflow.com/a/40369140/642706
long count = 0;
Set < DayOfWeek > weekend = EnumSet.of( DayOfWeek.SATURDAY , DayOfWeek.SUNDAY );
TemporalAdjuster nextWorkingDayTA = org.threeten.extra.Temporals.nextWorkingDay();
LocalDate ld = start;
if ( weekend.contains( ld.getDayOfWeek() ) ) {
ld = ld.with( nextWorkingDayTA );
}
while ( ld.isBefore( stop ) ) {
count++;
// Prepare for next loop.
ld = ld.with( nextWorkingDayTA ); // Increment to next working day (non-weekend day).
}
return count;
}
The last uses Java Streams approach seen in the Answer by Ravindra Ranwala.
private long countWeekDaysStream ( LocalDate start , LocalDate stop ) {
// Code taken from the Answer by Ravindra Ranwala.
// https://stackoverflow.com/a/51010738/642706
long count = 0;
Set < DayOfWeek > weekend = EnumSet.of( DayOfWeek.SATURDAY , DayOfWeek.SUNDAY );
final long weekDaysBetween = start.datesUntil( stop )
.filter( d -> ! weekend.contains( d.getDayOfWeek() ) )
.count();
return count;
}
And the test harness.
Caveats:
Well, the usual caveats about micro-benchmarking being untrustworthy, prone to unjustified or unrealistic conclusions.
I wish I'd learned to use the JMH micro-benchmarking framework.
I have not bothered to try optimizing any of this code. For example, in real work, the TemporalAdjuster could be cached outside our method.
Test harness.
LocalDate start = LocalDate.of( 2018 , Month.JANUARY , 1 );
LocalDate stop = start.plusYears( 1 );
int runs = 100_000;
long go = System.nanoTime();
for ( int i = 1 ; i <= runs ; i++ ) {
long count = this.countWeekDaysMath( start , stop );
}
long elapsedMath = ( System.nanoTime() - go );
go = System.nanoTime();
for ( int i = 1 ; i <= runs ; i++ ) {
long count = this.countWeekDaysVisit( start , stop );
}
long elapsedVisit = ( System.nanoTime() - go );
go = System.nanoTime();
for ( int i = 1 ; i <= runs ; i++ ) {
long count = this.countWeekDaysStream( start , stop );
}
long elapsedAdjuster = ( System.nanoTime() - go );
go = System.nanoTime();
for ( int i = 1 ; i <= runs ; i++ ) {
long count = this.countWeekDaysStream( start , stop );
}
long elapsedStream = ( System.nanoTime() - go );
System.out.println( "math: " + elapsedMath + " each: " + ( elapsedMath / runs ) );
System.out.println( "visit: " + elapsedVisit + " each: " + ( elapsedVisit / runs ) );
System.out.println( "adjuster: " + elapsedAdjuster + " each: " + ( elapsedAdjuster / runs ) );
System.out.println( "stream: " + elapsedStream + " each: " + ( elapsedStream / runs ) );
When run on my MacBook Pro (Sierra) with Oracle JDK 10.0.1 and ThreeTen-Extra version 1.3.2, I get results consistently close to the following. The math solution is a tiny fraction of the others at a couple hundred nanos versus several thousand, as we would expect obviously. Of the other three, the TemporalAdjuster is the longest, always over 10,000 nanos each. The visit and stream both come in well under that 10,000 nanos each, with visit being noticeably faster than streams. As seen in other examples around the internets, Java Streams usually make for nifty short code while often running significantly longer, about 20% longer in this case.
math: 18313309 each: 183
visit: 708420626 each: 7084
adjuster: 1002157240 each: 10021
stream: 924724750 each: 9247
About java.time
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 java.time.
To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.
Where to obtain the java.time classes?
Java SE 8 and SE 9 and later
Built-in.
Part of the standard Java API with a bundled implementation.
Java 9 adds some minor features and fixes.
Java SE 6 and SE 7
Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
Android
The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
See How to use….
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.
I used Shengyuan Lu's solution, but I needed to make a fix for the case where the method is called when one of the dates is on a Saturday and the other a Sunday - otherwise the answer is off by a day:
static long days(Date start, Date end){
//Ignore argument check
Calendar c1 = GregorianCalendar.getInstance();
c1.setTime(start);
int w1 = c1.get(Calendar.DAY_OF_WEEK);
c1.add(Calendar.DAY_OF_WEEK, -w1 + 1);
Calendar c2 = GregorianCalendar.getInstance();
c2.setTime(end);
int w2 = c2.get(Calendar.DAY_OF_WEEK);
c2.add(Calendar.DAY_OF_WEEK, -w2 + 1);
//end Saturday to start Saturday
long days = (c2.getTimeInMillis()-c1.getTimeInMillis())/(1000*60*60*24);
long daysWithoutSunday = days-(days*2/7);
if (w1 == Calendar.SUNDAY) {
w1 = Calendar.MONDAY;
}
if (w2 == Calendar.SUNDAY) {
w2 = Calendar.MONDAY;
}
return daysWithoutSunday-w1+w2;
}
Almost all the solutions are pretty much obsoleted and narrative. However here's a much condensed and readable solution.
This approach uses a Java Stream provided by the LocalDate::datesUntil method built into in Java 9 and later.
LocalDate startDate = LocalDate.of(2018, 5, 2);
LocalDate endDate = LocalDate.now();
Set<DayOfWeek> weekend = EnumSet.of(DayOfWeek.SATURDAY, DayOfWeek.SUNDAY);
final long weekDaysBetween = startDate.datesUntil(endDate)
.filter(d -> !weekend.contains(d.getDayOfWeek()))
.count();
.datesUntil returns a sequential ordered stream of dates. The
returned stream starts from this date (inclusive) and goes to
endExclusive (exclusive) by an incremental step of 1 day.
Then all the Saturdays and Sundays are filtered out. Final step is to get the count of the remaining week days.
Java-9 has been released one year ago, since using it now seems reasonable to me.
This thread is filled with failing solutions... I started by writing a little test file which met my needs, and saw that Roland's both solutions fails, Amir's too. I wanted a solution that uses java 8 and that does not uses loops because, do I have to say why ?
So here's the test file :
#Test
public void test() {
LocalDate d1 = LocalDate.of(2018, 8, 1);
LocalDate d2 = LocalDate.of(2018, 8, 2);
LocalDate d3 = LocalDate.of(2018, 8, 3);
LocalDate d4 = LocalDate.of(2018, 8, 4);
LocalDate d5 = LocalDate.of(2018, 8, 5);
LocalDate d6 = LocalDate.of(2018, 8, 6);
LocalDate d7 = LocalDate.of(2018, 8, 7);
LocalDate d8 = LocalDate.of(2018, 8, 8);
LocalDate d9 = LocalDate.of(2018, 8, 9);
LocalDate d10 = LocalDate.of(2018, 8, 10);
LocalDate d15 = LocalDate.of(2018, 8, 15);
LocalDate dsep = LocalDate.of(2018, 9, 5);
// same day : 0 days between
Assert.assertEquals(0, DateUtils.calcWeekDays1(d1, d1));
Assert.assertEquals(1, DateUtils.calcWeekDays1(d1, d2));
Assert.assertEquals(2, DateUtils.calcWeekDays1(d1, d3));
// end on week-end
Assert.assertEquals(2, DateUtils.calcWeekDays1(d1, d4));
Assert.assertEquals(2, DateUtils.calcWeekDays1(d1, d5));
// next week
Assert.assertEquals(3, DateUtils.calcWeekDays1(d1, d6));
Assert.assertEquals(4, DateUtils.calcWeekDays1(d1, d7));
Assert.assertEquals(5, DateUtils.calcWeekDays1(d1, d8));
Assert.assertEquals(6, DateUtils.calcWeekDays1(d1, d9));
Assert.assertEquals(7, DateUtils.calcWeekDays1(d1, d10));
// start on saturday
Assert.assertEquals(0, DateUtils.calcWeekDays1(d4, d5));
Assert.assertEquals(0, DateUtils.calcWeekDays1(d4, d6));
Assert.assertEquals(1, DateUtils.calcWeekDays1(d4, d7));
// start on sunday
Assert.assertEquals(0, DateUtils.calcWeekDays1(d5, d5));
Assert.assertEquals(0, DateUtils.calcWeekDays1(d5, d6));
Assert.assertEquals(1, DateUtils.calcWeekDays1(d5, d7));
// go to next week
Assert.assertEquals(10, DateUtils.calcWeekDays1(d1, d15));
// next month
Assert.assertEquals(25, DateUtils.calcWeekDays1(d1, dsep));
// start sat, go to next month
Assert.assertEquals(22, DateUtils.calcWeekDays1(d4, dsep));
}
And here is my proposed solution, quite simple. Just let java count the number of weeks, multiply by five, and add the number of days needed to compensate the difference ; the only trick is adjusting the start and end to avoid week-ends :
public static long calcWeekDays1(LocalDate start, LocalDate end) {
if (start.getDayOfWeek().getValue() > 5) {
start = start.with(TemporalAdjusters.next(DayOfWeek.MONDAY));
}
if (end.getDayOfWeek().getValue() > 5) {
end = end.with(TemporalAdjusters.previous(DayOfWeek.FRIDAY));
}
if (start.isAfter(end)) { // may happen if you start sat. and end sunday
return 0;
}
long weeks = ChronoUnit.WEEKS.between(start, end);
if (start.getDayOfWeek().getValue() > end.getDayOfWeek().getValue()) {
weeks += 1;
}
return 5 * weeks + end.getDayOfWeek().getValue() - start.getDayOfWeek().getValue();
}
And now I will look stupid if my code fails too :)
I don't have a Java based solution, but have a PHP one, hope it helps:
function getDate($days) {
for ($i = 0; $i < $days; $i ++) {
if (date('N' , strtotime('+' . ($i + 1) . ' days')) > 5) {
$days++;
}
}
return date('l, F jS', strtotime('+' . $days . ' days', time()));
}
This is my example without looping. Algorithm is same as 卢声远 Shengyuan Lus one but I used some features of JodaTime.
public static int getNumberOfBusinessDays(#Nonnull LocalDate from, #Nonnull LocalDate to) {
int fromDateDayOfWeek = from.getDayOfWeek();
int toDateDayOfWeek = to.getDayOfWeek();
int daysWithoutWeekends = 5 * Weeks.weeksBetween(
from.withDayOfWeek(DateTimeConstants.MONDAY), to).getWeeks();
if (fromDateDayOfWeek == DateTimeConstants.SUNDAY) {
fromDateDayOfWeek = DateTimeConstants.SATURDAY;
}
if (toDateDayOfWeek == DateTimeConstants.SUNDAY) {
toDateDayOfWeek = DateTimeConstants.SATURDAY;
}
return daysWithoutWeekends - (fromDateDayOfWeek - toDateDayOfWeek);
}
The do while in the solution of Piyush is wrong, it should be :
do {
if (startCal.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY && startCal.get(Calendar.DAY_OF_WEEK) != Calendar.SUNDAY) {
++workDays;
}
startCal.add(Calendar.DAY_OF_MONTH, 1);
} while (startCal.getTimeInMillis() < endCal.getTimeInMillis());
The startCal.add should add onto the Calendar.DATE field, not the Calendar.DAY_OF_MONTH, I was getting weird results with over Decemeber / January period.
This is my example without looping. It is a class in this example because I serialize it in some JSON output. Basically I work out the number of days between the two dates, divide by 7 and assign to a long to have a integer value for the number of weeks. Take the original number of days and subtract the number of weekends*2. This isn't quite perfect - you need to work out if there is a 'hangover' where the start is close to the end of the week and goes over the weekend. To correct for this I find the day of the week at the start and find the remainder of the number of days, and add those together to find the 'hangover' - and if it is more than 5 it is a weekend. It isn't quite perfect, and does not account for holidays at all. And no Joda in sight. That said there is also a issue with timezones.
import java.io.Serializable;
import java.util.Date;
public class BusinessDayCalculator implements Serializable {
private static long DAY = 86400000l;
private Date startTime;
private Date endTime;
public void setStartTime(Date startTime) {
this.startTime = startTime;
}
public Date getStartTime() {
return startTime;
}
public void setEndTime(Date endTime) {
this.endTime = endTime;
}
public Date getEndTime() {
return endTime;
}
public long getHours() {
return (this.endTime.getTime() - this.startTime.getTime())/(1000*60*60);
}
public long getBusinessDays(){
long startDay = getDayFromDate(this.startTime);
long endDay = getDayFromDate(this.endTime);
long totalDays = endDay-startDay;
long totalWeekends = totalDays/7;
long day = getDay(this.startTime);
long hangover = totalDays % 7;
long intoWeekend = day + hangover;
if(intoWeekend>5){
totalWeekends++;
}
long totalBusinessDays = totalDays - (totalWeekends *2);
/*
System.out.println("Days = " + day );
System.out.println("Hangover = " + hangover );
System.out.println("Total Days = " + totalDays);
System.out.println("Total Weekends = " + totalWeekends);
System.out.println("Total Business Days = " + totalBusinessDays);
*/
return totalBusinessDays;
}
private long getDayFromDate( Date date ){
long d = date.getTime() / DAY;
return d;
}
private long getDay( Date date ){
long daysSinceEpoc = getDayFromDate(date);
long day = daysSinceEpoc % 7;
day = day + 4;
if(day>6) day = day - 7;
return day;
}
}
Solution for Java 8 without loop and INCLUSIVE intervals:
public long getDaysWithoutSundays(LocalDate startDate, LocalDate endDate) {
long numberOfDays = ChronoUnit.DAYS.between(startDate, endDate) + 1;
long numberOfSundays = numberOfDays / 7;
long rest = numberOfDays % 7;
if (rest > 0) {
int startToEnd = startDate.getDayOfWeek().getValue() - endDate.getDayOfWeek().getValue();
if (startToEnd > 0) {
numberOfSundays++;
}
else {
if (endDate.getDayOfWeek().equals(DayOfWeek.SUNDAY)) {
numberOfSundays++;
}
}
}
return numberOfDays - numberOfSundays;
}
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
/**
*
* #author varun.vishwakarma
*
*/
public class FindWeekendsInDateRange {
static HashMap<Integer, String> daysOfWeek=null;
static {
daysOfWeek = new HashMap<Integer, String>();
daysOfWeek.put(new Integer(1), "Sun");
daysOfWeek.put(new Integer(2), "Mon");
daysOfWeek.put(new Integer(3), "Tue");
daysOfWeek.put(new Integer(4), "Wed");
daysOfWeek.put(new Integer(5), "Thu");
daysOfWeek.put(new Integer(6), "Fri");
daysOfWeek.put(new Integer(7), "Sat");
}
/**
*
* #param from_date
* #param to_date
* #return
*/
public static List<Date> calculateWeekendsInDateReange(Date fromDate, Date toDate) {
List<Date> listOfWeekends = new ArrayList<Date>();
Calendar from = Calendar.getInstance();
Calendar to = Calendar.getInstance();
from.setTime(fromDate);
to.setTime(toDate);
while (from.getTimeInMillis() < to.getTimeInMillis()) {
if (daysOfWeek.get(from.get(Calendar.DAY_OF_WEEK)) == "Sat") {
Date sat = from.getTime();
listOfWeekends.add(sat);
} else if (daysOfWeek.get(from.get(Calendar.DAY_OF_WEEK)) == "Sun") {
Date sun = from.getTime();
listOfWeekends.add(sun);
}
from.add(Calendar.DAY_OF_MONTH, 1);
}
return listOfWeekends;
}
public static void main(String[] args) {
String fromDate = "7-Oct-2019";
String toDate = "25-Oct-2019";
System.out.println(FindWeekendsInDateRange.calculateWeekendsInDateReange(new Date(fromDate), new Date(toDate)));
}
}
I'm surprised that every solution given here fails to account for business holidays, which occur in most countries every few months at least, so any span more than a few months will give an incorrect answer. Fortunately, Ravindra's answer using Streams is, despite the inconsequential (for spans under ~10 years) overhead, the best one because it is trivial to correct:
import java.time.*;
import java.util.*;
import static java.time.temporal.ChronoUnit.DAYS;
public class WeekDaysLeft {
public static void main(String[] args) {
LocalDate startDate = LocalDate.now(); // Early 2023
LocalDate endDate = LocalDate.of(2023, 6, 23);
Set<DayOfWeek> weekendDays =
EnumSet.of(DayOfWeek.SATURDAY, DayOfWeek.SUNDAY);
Set<LocalDate> holidays =
Set.of(LocalDate.of(2023,4,7),
LocalDate.of(2023,4,10));
final long weekDaysBetween =
startDate.datesUntil(endDate)
.filter(d -> !weekendDays.contains(
d.getDayOfWeek()))
.filter(d -> !holidays.contains(d))
.count();
System.out.println(weekDaysBetween);
}
}
In regard to my claim that the overhead is inconsequential:
Run my solution under time(1) on Unix/Linux
e.g., time java WeekDaysLeft.java
Change the end-date to 2033, and repeat step 1.
On my system, the user time went DOWN slightly (user time up trivially).
And, of course, if you're running this after June, 2023, bump all the years given.
This program considers loop approach but consider activities happened on after work hours to next working day office start hour
public class BusinessDayCalculator {
private final String DATE_FORMAT = "dd/MM/yyyy HH:mm:ss";
private final int OFFICE_START_HOUR = 9;
private final int OFFICE_CLOSE_HOUR = 17;
private final int TOTAL_MINS_IN_BUSINESS_DAY = (OFFICE_CLOSE_HOUR - OFFICE_START_HOUR)*60;
public void dateDifference(String start, String end){
Date startDate = validateStringToDate(start);
Date endDate = validateStringToDate(end);
System.out.println(startDate);
System.out.println(endDate);
Calendar startDay = convertDateToCalendar(startDate);
Calendar tempDay = (Calendar) startDay.clone();
Calendar endDay = convertDateToCalendar(endDate);
System.out.println(startDay.getTime());
System.out.println(endDay.getTime());
int workDays = -1;
int startDayDifference = 0;
int endDayDifference = 0;
int hours = 0;
int minsRemainder = 0;
if(!(startDay.get(Calendar.DAY_OF_YEAR) == endDay.get(Calendar.DAY_OF_YEAR)
&& startDay.get(Calendar.YEAR) == endDay.get(Calendar.YEAR))){
do{
tempDay.add(Calendar.DAY_OF_MONTH, 1);
if(tempDay.get(Calendar.DAY_OF_WEEK) != Calendar.SATURDAY
&& tempDay.get(Calendar.DAY_OF_WEEK) != Calendar.SUNDAY){
workDays++;
}
}while(tempDay.getTimeInMillis() <= endDay.getTimeInMillis());
if(workDays > 0){
workDays = workDays - 1;
}
}
startDayDifference = hourDifferenceInMinutesOfStartDay(startDay);
endDayDifference = hourDifferenceInMinutesOfEndDay(endDay);
minsRemainder = (startDayDifference + endDayDifference) % TOTAL_MINS_IN_BUSINESS_DAY;
workDays = workDays + ((startDayDifference + endDayDifference) / TOTAL_MINS_IN_BUSINESS_DAY);
hours = minsRemainder/60;
minsRemainder = minsRemainder % 60;
System.out.println(workDays + "d "+ hours + "hrs " + minsRemainder + " mins");
}
private int hourDifferenceInMinutesOfEndDay(Calendar endDay) {
long endTimestamp = endDay.getTimeInMillis();
System.out.println(endTimestamp);
endDay.set(Calendar.HOUR_OF_DAY, OFFICE_START_HOUR);
endDay.set(Calendar.MINUTE,0);
long endDayOfficeStartTimestamp = endDay.getTimeInMillis();
System.out.println(endDayOfficeStartTimestamp);
int difference = (int)((endTimestamp - endDayOfficeStartTimestamp) / 1000) / 60;
System.out.println(difference);
return difference;
}
private int hourDifferenceInMinutesOfStartDay(Calendar startDay) {
long starttimestamp = startDay.getTimeInMillis();
System.out.println(starttimestamp);
startDay.set(Calendar.HOUR_OF_DAY, OFFICE_CLOSE_HOUR);
startDay.set(Calendar.MINUTE,0);
long startDayOfficeCloseTimestamp = startDay.getTimeInMillis();
System.out.println(startDayOfficeCloseTimestamp);
int difference = (int)((startDayOfficeCloseTimestamp - starttimestamp) / 1000) / 60;
System.out.println(difference);
return difference;
}
public Calendar convertDateToCalendar(Date date){
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);
if(calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY
|| calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY){
calendar = handleActivityOnAfterWorkHoursOrWeekendOrHolidays(calendar);
}
if(calendar.get(Calendar.HOUR_OF_DAY) >= OFFICE_CLOSE_HOUR
&& calendar.get(Calendar.MINUTE) > 0){
calendar = handleActivityOnAfterWorkHoursOrWeekendOrHolidays(calendar);
}
if(calendar.get(Calendar.HOUR_OF_DAY) < OFFICE_START_HOUR){
calendar.set(Calendar.HOUR_OF_DAY, OFFICE_START_HOUR);
calendar.set(Calendar.MINUTE,0);
}
return calendar;
}
private Calendar handleActivityOnAfterWorkHoursOrWeekendOrHolidays(Calendar calendar) {
do{
calendar.add(Calendar.DAY_OF_MONTH, 1);
}while(isHoliday(calendar));
calendar.set(Calendar.HOUR_OF_DAY, OFFICE_START_HOUR);
calendar.set(Calendar.MINUTE,0);
return calendar;
}
private boolean isHoliday(Calendar calendar) {
if(calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY
|| calendar.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY){
return true;
}
return false;
}
public Date validateStringToDate(String input){
SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT);
Date date = null;
try{
date = dateFormat.parse(input);
}catch(ParseException exception){
System.out.println("invalid date format");
throw new RuntimeException("invalid date format");
}
return date;
}
public static void main(String[] args){
BusinessDayCalculator calc = new BusinessDayCalculator();
String startDate = "27/12/2016 11:38:00";
String endDate = "04/01/2017 12:38:00";
calc.dateDifference(startDate, endDate);
}
}
In groovy:
public static int getWorkingDaysBetweenDates (Date start, Date end) {
def totalDays = (Integer) (end.getTime() - start.getTime()) / (1000 * 60 * 60 * 24)
def int workingDays = 0
(0..totalDays).each { def dow = (start + it)[Calendar.DAY_OF_WEEK]; if(dow != Calendar.SATURDAY && dow != Calendar.SUNDAY){workingDays++} }
workingDays
}
Using java 8 it can be easily done, example function:
long getBusinessDaysDifference(LocalDate startDate, LocalDate endDate) {
EnumSet<DayOfWeek> weekend = EnumSet.of(DayOfWeek.SATURDAY, DayOfWeek.SUNDAY);
List<LocalDate> list = Lists.newArrayList();
LocalDate start = startDate;
while (start.isBefore(endDate)) {
list.add(start);
start = start.plus(1, ChronoUnit.DAYS);
}
long numberOfDays = list.stream().filter(d -> !weekend.contains(d.getDayOfWeek())).count();
return numberOfDays;
}
Description:
Define your off-days in an EnumSet (weekends in this case).
Create a list holding all the days between the startDate and endDate.
Reduce the outcome list by removing any occurrence of a day from the EnumSet.
Then finally count the size of this reduced list.
Note: this function can be optimized, but might be helpful as a starting point.
public long getNumberOfWeekDayBetweenDates(LocalDate startDate, LocalDate endDate, String dayOfWeek) {
long result = -1;
if (startDate != null && endDate != null && dayOfWeek != null && (startDate.isBefore(endDate) || startDate.isEqual(endDate))) {
java.time.DayOfWeek givenDayOfWeek = java.time.DayOfWeek.valueOf(dayOfWeek);
// find the first given day of week in the interval
LocalDate firstOccurrence = startDate.with(TemporalAdjusters.nextOrSame(givenDayOfWeek));
// similarly find last Monday
LocalDate lastOccurrence = endDate.with(TemporalAdjusters.previousOrSame(givenDayOfWeek));
if (firstOccurrence != null && lastOccurrence != null) {
// count the number of weeks between the first and last occurrence, then add 1 as end day is exclusive
result = ChronoUnit.WEEKS.between(firstOccurrence, lastOccurrence) + 1;
} else if (firstOccurrence == null && lastOccurrence == null) {
// no occurrence
result = 0;
} else {
result = 1;
}
}
return result;
}
Here is a set-based solution that completes in constant time for any given subset of weekdays, not just Monday-Friday. It splits the problem into counting full weeks and counting the days in the residual week. If you are interested, here's a detailed explanation and a formal proof that the algorithm is correct. Note that the intervals are inclusive, i.e. startDate and endDate are counted in. If startDate is after endDate, the result is zero rather than negative.
long countWeekDays(LocalDate startDate, LocalDate endDate, Set<DayOfWeek> daysOfWeek) {
long periodLength = Math.max(0, ChronoUnit.DAYS.between(startDate, endDate) + 1);
long fullWeeks = periodLength / 7;
long residualWeekLength = periodLength % 7;
Set<DayOfWeek> residualWeekDays = LongStream.range(0, residualWeekLength)
.mapToObj(offset -> startDate.plusDays(offset).getDayOfWeek())
.collect(Collectors.toSet());
residualWeekDays.retainAll(daysOfWeek);
return fullWeeks * daysOfWeek.size() + residualWeekDays.size();
}
For the original problem (Monday-Friday) it is called e.g. with:
countWeekDays(
LocalDate.of(2016, 2, 8),
LocalDate.of(2016, 2, 26),
new HashSet(Arrays.asList(
DayOfWeek.MONDAY,
DayOfWeek.TUESDAY,
DayOfWeek.WEDNESDAY,
DayOfWeek.THURSDAY,
DayOfWeek.FRIDAY
)
)
)
This assumes you are working with inclusive intervals. If you want to skip the first day of the interval, just add one day to the first parameter:
countWeekDays(
LocalDate.of(2016, 2, 8).plusDays(1),
LocalDate.of(2016, 2, 26),
new HashSet(Arrays.asList(
DayOfWeek.MONDAY,
DayOfWeek.TUESDAY,
DayOfWeek.WEDNESDAY,
DayOfWeek.THURSDAY,
DayOfWeek.FRIDAY
)
)
)
Likewise, if you want to skip the last day of the inclusive interval, subtract one day from the second parameter:
countWeekDays(
LocalDate.of(2016, 2, 8),
LocalDate.of(2016, 2, 26).minusDays(1),
new HashSet(Arrays.asList(
DayOfWeek.MONDAY,
DayOfWeek.TUESDAY,
DayOfWeek.WEDNESDAY,
DayOfWeek.THURSDAY,
DayOfWeek.FRIDAY
)
)
)
Finally, if you need to skip both interval-delimiting days, combine the two previous modifications:
countWeekDays(
LocalDate.of(2016, 2, 8).plusDays(1),
LocalDate.of(2016, 2, 26).minusDays(1),
new HashSet(Arrays.asList(
DayOfWeek.MONDAY,
DayOfWeek.TUESDAY,
DayOfWeek.WEDNESDAY,
DayOfWeek.THURSDAY,
DayOfWeek.FRIDAY
)
)
)
For LocalDate supported by latest java version you can try below function.
It provides support of functiongetDayOfWeek().
The getDayOfWeek() method of LocalDate class in Java gets the day-of-week field, which is an enum DayOfWeek.
public static int getWeekEndCount(LocalDate fromDate, LocalDate toDate) {
int saturday = 0;
int sunday = 0;
while (!fromDate.isAfter(toDate)) {
if (fromDate.getDayOfWeek().equals(DayOfWeek.SATURDAY))
saturday++;
else if (fromDate.getDayOfWeek().equals(DayOfWeek.SUNDAY))
sunday++;
fromDate = fromDate.plusDays(1);
}
System.out.println("Saturday count=="+saturday);
System.out.println("Sunday count=="+sunday);
return saturday+sunday;
}