Have next function to get week of year:
static public Integer getWeek(Date date) {
Calendar cal = Calendar.getInstance();
cal.setMinimalDaysInFirstWeek(1);
cal.setTime(date);
Integer week = cal.WEEK_OF_YEAR;
Integer month = cal.MONTH;
if ((week == 1) && (month == 12)) week = 52;
return week;
}
Call the function with date=02.01.2013
What I see in debug:
date = Wed Jan 02 00:00:00 SAMT 2013
week = 3
month = 2
I want to get: week=1, month=1. Right?
Where am I wrong?
JRE 1.6
Thanks a lot for advance.
Calendar.WEEK_OF_YEAR and Calendar.MONTH are static constants Calendar uses to look up fields. You want
Integer week = cal.get(Calendar.WEEK_OF_YEAR);
Integer month = cal.get(Calendar.MONTH);
Also, note that (I think) January is considered month 0.
public final static int WEEK_OF_YEAR = 3; is inside source of Calendar.
When you access WEEK_OF_YEAR it prints value of this field, it would be treated like accessing static field of Calendar class.
If you want get week, you need to do Integer week = cal.get(Calendar.WEEK_OF_YEAR);
Related
I have a date and a time of a month, for example 31/01/2020 at 14:00:00, this is the last friday of January. How can I get the date for the last Friday of Feb, March, etc.? It should be dynamic because any date can come in, like the second Tuesday of any month and so on.
I am trying with the following with no luck:
LocalDateTime startTime = LocalDateTime.of(2020, 1, 31, 14, 0, 0);
final Calendar calendar = Calendar.getInstance();
calendar.set(startTime.getYear(), startTime.getMonthValue() - 1, startTime.getDayOfMonth(), startTime.getHour(), startTime.getMinute(), startTime.getSecond());
int ordinal = calendar.get(Calendar.WEEK_OF_MONTH);
startTime = startTime.plusMonths(1).with(TemporalAdjusters.dayOfWeekInMonth(ordinal, startTime.getDayOfWeek();
System.out.println(startTime);
it's printing 06/03/2020 (six of march) at 14:00:00 which is wrong and should be 28/02/2020
What am I missing?
Thanks!
As mentioned before, there is some ambiguity in which day of the week of the month you mean, that is, whether you mean the nth day of week or the last nth day of week of the month.
One such example is Monday, February 24th, 2020. It is the fourth and last Monday of February 2020. If you are going to try to determine this for March 2020, which Monday would you pick? The fourth Monday is 23 March, but the last Monday is 30 March.
So apparently, you'll need to distinguish between whether you count forward or backward.
You could, for instance, create a class which represents a certain day of week in a month. This holds three fields: a day-of-week, a position, and whether the position is backwards or not. E.g.
"The second Monday of the month" would have
dayOfWeek = DayOfWeek.MONDAY
position = 2
backwards = false
and
"The last Thursday of the month" would have
dayOfWeek = DayOfWeek.THURSDAY
position = 1
backwards = true
public class WeekdayInMonth {
private final boolean backwards;
private final DayOfWeek dayOfWeek;
private final int position;
private WeekdayInMonth(DayOfWeek dayOfWeek, int position, boolean backwards) {
if (position < 1 || position > 5) {
throw new DateTimeException("Position in month must be between 1 and 5 inclusive");
}
this.dayOfWeek = dayOfWeek;
this.position = position;
this.backwards = backwards;
}
}
We could add factory methods to create WeekdayInMonths from LocalDates:
public static WeekdayInMonth of(LocalDate date) {
int positionInMonth = (date.getDayOfMonth() - 1) / 7 + 1;
return new WeekdayInMonth(date.getDayOfWeek(), positionInMonth, false);
}
private static WeekdayInMonth ofReversing(LocalDate date) {
int lastDayOfMonth = date.with(TemporalAdjusters.lastDayOfMonth()).getDayOfMonth();
int positionInMonth = (lastDayOfMonth - date.getDayOfMonth()) / 7 + 1;
return new WeekdayInMonth(date.getDayOfWeek(), positionInMonth, true);
}
At last, we add a method to get a LocalDate from a YearMonth adjusted to the WeekdayInMonth.
public LocalDate toLocalDate(YearMonth yearMonth) {
// Get a temporal adjuster to adjust a LocalDate to match a day-of-the-week
TemporalAdjuster adjuster = this.backwards ? TemporalAdjusters.lastInMonth(this.dayOfWeek) : TemporalAdjusters.firstInMonth(this.dayOfWeek);
int weeks = this.position - 1;
LocalDate date = yearMonth.atDay(1)
.with(adjuster)
.plusWeeks(this.backwards ? 0 - weeks : weeks);
if (!Objects.equals(yearMonth, YearMonth.from(date))) {
throw new DateTimeException(String.format("%s #%s in %s does not exist", this.dayOfWeek, this.position, yearMonth));
}
return date;
}
Working example
Here a working example at Ideone.
Addendum
I am getting errors like this if the initial date is Jan 1 2020: java.time.DateTimeException: FRIDAY #5 in 2020-02 does not exist. How could I get the previous weekday in case this happens? In this case, how would I get the previous Friday?
Well, then you need to adjust your LocalDate so that it falls within the specified yearmonth. Since every month has at least four day-of-the-weeks and no more than five of them, the difference is never more than a week. We could, after removing the throw new DateTimeException line, simply adjust the returned LocalDate using plusWeeks.
I've forked the abovementioned example and added the toAdjustingLocalDate method.
This solution is kind of complicated but this is because "last of" or "third in" etc aren't always well defined and might not even exists under some conditions. So here is a solution that looks at the initial date and depending of the day of the month it either performs calculations from the start of the month, calculating forward, or the end of the month, calculating backwards.
From my testing it seems to generate the right results and I am sure some code refactoring could be done as well to improve the code but I leave that for the reader.
public static LocalDateTime nextWithSameDayOfMonth(LocalDateTime indate) {
if (indate.getDayOfMonth() < 15) {
return getForStartOfMonth(indate);
}
return getForEndOfMonth(indate);
}
private static LocalDateTime getForEndOfMonth(LocalDateTime indate) {
DayOfWeek dayOfWeek = indate.getDayOfWeek();
LocalDateTime workDate = indate.with(TemporalAdjusters.lastDayOfMonth());
int count = 0;
while (workDate.isAfter(indate)) {
count++;
workDate = workDate.minusWeeks(1);
}
LocalDateTime nextDate = indate.plusMonths(1).with(TemporalAdjusters.lastDayOfMonth());
while (nextDate.getDayOfWeek() != dayOfWeek) {
nextDate = nextDate.minusDays(1);
}
return count == 0 ? nextDate : nextDate.minusWeeks(count - 1);
}
private static LocalDateTime getForStartOfMonth(LocalDateTime indate) {
DayOfWeek dayOfWeek = indate.getDayOfWeek();
LocalDateTime workDate = indate.with(TemporalAdjusters.firstDayOfMonth());
int count = 0;
while (workDate.isBefore(indate)) {
count++;
workDate = workDate.plusWeeks(1);
}
LocalDateTime nextDate = indate.plusMonths(1).with(TemporalAdjusters.firstDayOfMonth());
while (nextDate.getDayOfWeek() != dayOfWeek) {
nextDate = nextDate.plusDays(1);
}
return count == 0 ? nextDate : nextDate.plusWeeks(count - 1);
}
Could you check if the function work for you?
public class FindSameDayNextMonth {
public static void main(String[] args) {
System.out.println("Next month of 'today' is " + FindSameDayNextMonth.getSameDayNextMonth());
}
public static Date getSameDayNextMonth() {
LocalDateTime dt = LocalDateTime.now();
Calendar c = Calendar.getInstance();
c.set(Calendar.MONTH, dt.getMonthValue()-1);
c.set(Calendar.DAY_OF_MONTH, dt.getDayOfMonth());
c.add(Calendar.MONTH, 1);
return c.getTime();
}
}
The output is
Next month of today is Mon Sep 23 07:18:09 CDT 2019
Here in the UK, the tax year runs from 6 April to 5 April each year. I want to get the start date of the current tax year (as a LocalDate), so for example if today is 3 April 2020, then return 6 April 2019, and if today is 8 April 2020, then return 6 April 2020.
I can calculate it using some logic like the following:
date = a new LocalDate of 6 April with today's year
if (the date is after today) {
return date minus 1 year
} else {
return date
}
But is there some method I can use that is less complex and uses a more succinct, perhaps functional style?
There are a few different approaches, but it's easy enough to implement the logic you've already specified in a pretty functional style:
private static final MonthDay FINANCIAL_START = MonthDay.of(4, 6);
private static LocalDate getStartOfFinancialYear(LocalDate date) {
// Try "the same year as the date we've been given"
LocalDate candidate = date.with(FINANCIAL_START);
// If we haven't reached that yet, subtract a year. Otherwise, use it.
return candidate.isAfter(date) ? candidate.minusYears(1) : candidate;
}
That's pretty concise and simple. Note that it doesn't use the current date - it accepts a date instead. That makes it much easier to test. It's easy enough to call this and provide the current date, of course.
using java.util.Calendar, you can get financial year's START and END date in which your given date lies.
In India financial year starts from from 1 April and ends on 31st March,
for financial year 2020-21 , dates will be 1 April 2020
public static Date getFirstDateOfFinancialYear(Date dateToCheck) {
int year = getYear(dateToCheck);
Calendar cal = Calendar.getInstance();
cal.set(year, 3, 1); // 1 April of Year
Date firstAprilOfYear = cal.getTime();
if (dateToCheck.after(firstAprilOfYear)) {
return firstAprilOfYear;
} else {
cal.set(year - 1, 3, 1);
return cal.getTime();
}
}
In your case set cal.set(year, 0, 1); // 1 Jan of Year
public static Date getLastDateOfFinancialYear(Date dateToCheck) {
int year = getYear(dateToCheck);
Calendar cal = Calendar.getInstance();
cal.set(year, 2, 31); // 31 March of Year
Date thirtyFirstOfYear = cal.getTime();
if (dateToCheck.after(thirtyFirstOfYear)) {
cal.set(year + 1, 2, 31);
return cal.getTime();
} else {
return thirtyFirstOfYear;
}
}
In your case set cal.set(year, 11, 31); // 31 Dec of Year
public static void main(String[] args) {
int week = 1;
int year = 2010;
Calendar calendar = Calendar.getInstance();
calendar.clear();
calendar.set(Calendar.WEEK_OF_YEAR, week);
calendar.set(Calendar.YEAR, year);
Date date = calendar.getTime();
System.out.println(date);
}
I'm looking for the exact start and end DATE's as per our desktop calendars if I give week, year as input.
But the above code is giving the output as 27th Jan, 2009, Sunday.
I know it's because the default first day of a week is SUNDAY as per US, but I need as per the desktop calendar 1st Jan, 2010, Friday as starting date of the week
My Requirement :
If my input is :
Week as '1',
Month as '5',
Year as '2015'
I need :
1st May, 2015 --> as first day of the week
2nd May, 2015 --> as last day of the week
If my input is :
Week as '1',
Month as '6',
Year as '2015'
I need :
1st June, 2015 --> as first day of the week
6th June, 2015 --> as last day of the week
Can anyone help me?
Instead of using CALENDAR.Week, use Calendar.DAY_OF_YEAR. I just tested it and it works for me:
public static void main(String[] args) {
Calendar calendar = Calendar.getInstance();
calendar.clear();
calendar.set(Calendar.YEAR, 2010);
calendar.set(Calendar.DAY_OF_YEAR, 1);
System.out.println(calendar.getTime());
calendar.set(Calendar.DAY_OF_YEAR, 7);
System.out.println(calendar.getTime());
}
If you want this to work for an arbitrary week, just do some math to figure out which day of the year you want.
Edit: If you want to input a month as well, you can use Calendar.DAY_OF_MONTH.
I wrote a Swing calendar widget. One method in that widget calculates the first day of the week when a week starts on a user selected day, like Friday.
startOfWeek is an int that takes a Calendar constant, like Calendar.FRIDAY.
DAYS_IN_WEEK is an int constant with the value 7.
/**
* This method gets the date of the first day of the calendar week. It could
* be the first day of the month, but more likely, it's a day in the
* previous month.
*
* #param calendar
* - Working <code>Calendar</code> instance that this method can
* manipulate to set the first day of the calendar week.
*/
private void getFirstDate(Calendar calendar) {
int dayOfWeek = calendar.get(Calendar.DAY_OF_WEEK) % DAYS_IN_WEEK;
int amount = 0;
for (int i = 0; i < DAYS_IN_WEEK; i++) {
int j = (i + startOfWeek) % DAYS_IN_WEEK;
if (j == dayOfWeek) {
break;
}
amount--;
}
calendar.add(Calendar.DAY_OF_MONTH, amount);
}
The rest of the code can be seen in my article, Swing JCalendar Component.
I am trying to set properties for a Calendar class instance. But each time I get to Dec 30, it resets to the next year. Is this a draw in the Calendar class?
public Calendar setCalendar()
{
String Date = "2013-12-30";
int yyyy = Integer.parseInt(date.substring(0,4));
int mm = Integer.parseInt(date.substring(5,7));
int dd = Integer.parseInt(date.substring(8,10));
System.out.println(yyyy + " " + mm + " " + dd);
Calendar Cal= new GregorianCalendar();
Cal.set(yyyy,mm,dd);
System.out.println(Cal.get(Calendar.YEAR)+","+Cal.get(Calendar.MONTH));
return Cal;
}
Output:
2013 12 30
2014,0
With Calendar the months are 0-based, so you're actually setting the month to next year's January.
If you really need to use a Calendar I recommend at least using a SimpleDateFormat to parse your String to a Date and setting the calendar using that.
Check the Calendar API doc, month value is 0 based i.e Jan is 0.
month - the value used to set the MONTH calendar field. Month value is 0-based. e.g., 0 for January.
You are setting month to 12. This effectively gives you the next year. To correct try:
Cal.set(yyyy,mm-1,dd);
Hope that helps
I'm trying to create a method which is checking if "today" is between Monday and Friday. For this I get with this line 'int day = Calendar.DAY_OF_WEEK;' the actual day. After that I fill a ArrayList with the days (Monday, Tuesday, Wendsday, Thursday and Friday). Now when I check if the actual day is in my ArrayList, i set boolean DAY = true else i set boolean DAY = false. I tryed the Method today and yesterday, but it allways sets the boolean to false.
What do I need to change that my code works? You'll find the code down here.
Code
int day = Calendar.DAY_OF_WEEK;
ArrayList<Integer> daylist = new ArrayList<Integer>();
daylist.add(Calendar.MONDAY);
daylist.add(Calendar.TUESDAY);
daylist.add(Calendar.WEDNESDAY);
daylist.add(Calendar.THURSDAY);
daylist.add(Calendar.FRIDAY);
if (daylist.contains(day)){
DAY = true;
}else{
DAY = false;
}
Wow, that's like trying to kill a mosquito with a thermo-nuclear warhead :-)
Java guarantees (in 1.5) (unchanged up to 1.8 at least) that the values of SUNDAY through SATURDAY are contiguous (1 through 7) so it's a simple matter of checking a range.
However, DAY_OF_WEEK is not the day of the week, it's a field number (with the value 7) to be passed to the getter to retrieve the day of the week. The only time Calendar.DAY_OF_WEEK itself will match an actual day will be on Saturdays.
You can use code such as:
Calendar myDate = Calendar.getInstance(); // set this up however you need it.
int dow = myDate.get (Calendar.DAY_OF_WEEK);
boolean isWeekday = ((dow >= Calendar.MONDAY) && (dow <= Calendar.FRIDAY));
Following this, isWeekday will be true if and only if the day from myDate was Monday through Friday inclusive.
int day = Calendar.DAY_OF_WEEK; should instead be
Calendar cal; // The calendar object
....your other code for getting the date goes here....
int day = cal.get(Calendar.DAY_OF_WEEK);
Your current code just gets the value of the constant Calendar.DAY_OF_WEEK.
This should do the trick for you i assume.
int day = cal.get(Calendar.DAY_OF_WEEK);
if (day >= Calendar.MONDAY && day <= Calendar.FRIDAY){
DAY = true;
}else{
DAY = false;
}
int day = Calendar.DAY_OF_WEEK;
The logic is broken right here. DAY_OF_WEEK is a constant identifying which type of data we need to retrieve from a Calendar instance.
The simplest solution to your problem (since Calendar.FRIDAY > ... > Calendar.MONDAY) is
Calendar now = Calendar.getInstance();
int day = now.get(Calendar.DAY_OF_WEEK);
if (day >= Calendar.MONDAY && day <= Calendar.FRIDAY)
// do something
First Calendar.DAY_OF_WEEK is an integer field will always gives you 7. You need to create an instance of a Calendar like Calendar cal = Calendar.getInstance(); By default it gives you the current date in current timezone.
Then you can call cal.get(Calendar.DAY_OF_WEEK); which will give you any day between Sunday and Sat'day
Now you can check something like this
if(cal.get(Calendar.DAY_OF_WEEK) == Calendar.SUNDAY || cal.get(Calendar.DAY_OF_WEEK) == Calendar.SATURDAY) {
System.out.println("Weekend");
} else {
System.out.println("Weekday");
}
You can apply this logic to your problem!!