Plase have a look at the below code
Calendar date = Calendar.getInstance();
initialClientLetterDate.setText(date.get(Calendar.YEAR)+"/"+date.get(Calendar.MONTH)+"/"+date.get(Calendar.DAY_OF_WEEK));
This generates the invalid "month" and "date". The output is 2014/09/06. Why is this? I just wanted to get current year, date and month.
You are using DAY_OF_WEEK which is 6 for FRIDAYand MONTH starts from 0 not 1 so you have to add 1 in it.You can use DAY_OF_MONTH instead of DAY_OF_WEEK.
You can do like as below code. You should not forgot to set locale.
public static void main(String args[]) {
Calendar date = Calendar.getInstance(Locale.US);
System.out.println(date.get(Calendar.YEAR) + "/"
+ (date.get(Calendar.MONTH) + 1) + "/"
+ date.get(Calendar.DAY_OF_MONTH));
}
DAY_OF_WEEK Returns an int (starting at 1?) for the day in the week so Friday would be 6, Month does the same except starting at 0 so 09 would be October.
http://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#DAY_OF_WEEK
date.get(Calendar.YEAR) = Gives the current year
date.get(Calendar.MONTH) = Gives the month of the year as an integer from 0 to 11, where 0 = Jan and 11 = dec
date.get(Calendar.DAY_OF_WEEK) = Gives the day of the week from 0 to 6, where 0 = Monday
So if you want to get the current date you must do
date.get(Calendar.YEAR)+"/"+(date.get(Calendar.MONTH)+1)+"/"+date.get(Calendar.DAY_OF_MONTH)
Related
I want to get the last and the first week of a week for a given date.
e.g if the date is 12th October 2011 then I need the dates 10th October 2011 (as the starting date of the week) and 16th october 2011 (as the end date of the week)
Does anyone know how to get these 2 dates using the calender class (java.util.Calendar)
thanks a lot!
Some code how to do it with the Calendar object. I should also mention joda time library as it can help you many of Date/Calendar problems.
Code
public static void main(String[] args) {
// set the date
Calendar cal = Calendar.getInstance();
cal.set(2011, 10 - 1, 12);
// "calculate" the start date of the week
Calendar first = (Calendar) cal.clone();
first.add(Calendar.DAY_OF_WEEK,
first.getFirstDayOfWeek() - first.get(Calendar.DAY_OF_WEEK));
// and add six days to the end date
Calendar last = (Calendar) first.clone();
last.add(Calendar.DAY_OF_YEAR, 6);
// print the result
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(df.format(first.getTime()) + " -> " +
df.format(last.getTime()));
}
This solution works for any locale (first day of week could be Sunday or Monday).
Date date = new Date();
Calendar c = Calendar.getInstance();
c.setTime(date);
int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - c.getFirstDayOfWeek();
c.add(Calendar.DAY_OF_MONTH, -dayOfWeek);
Date weekStart = c.getTime();
// we do not need the same day a week after, that's why use 6, not 7
c.add(Calendar.DAY_OF_MONTH, 6);
Date weekEnd = c.getTime();
For example, today is Jan, 29 2014. For the locale with Sunday as a first day of week you will get:
start: 2014-01-26
end: 2014-02-01
For the locale with Monday as a first day the dates will be:
start: 2014-01-27
end: 2014-02-02
If you want all dates then
first.add(Calendar.DAY_OF_WEEK,first.getFirstDayOfWeek() - first.get(Calendar.DAY_OF_WEEK));
for (int i = 1; i <= 7; i++) {
System.out.println( i+" Day Of that Week is",""+first.getTime());
first.add(Calendar.DAY_OF_WEEK,1);
}
Here is the sample code
public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
cal.set(2016, 2, 15);
{
Calendar startCal = Calendar.getInstance();
startCal.setTimeInMillis(cal.getTimeInMillis());
int dayOfWeek = startCal.get(Calendar.DAY_OF_WEEK);
startCal.set(Calendar.DAY_OF_MONTH,
(startCal.get(Calendar.DAY_OF_MONTH) - dayOfWeek) + 1);
System.out.println("end date : " + startCal.getTime());
}
{
Calendar endCal = Calendar.getInstance();
endCal.setTimeInMillis(cal.getTimeInMillis());
int dayOfWeek = endCal.get(Calendar.DAY_OF_WEEK);
endCal.set(Calendar.DAY_OF_MONTH, endCal.get(Calendar.DAY_OF_MONTH)
+ (7 - dayOfWeek));
System.out.println("start date : " + endCal.getTime());
}
}
which will print
start date : Sun Mar 13 20:30:30 IST 2016
end date : Sat Mar 19 20:30:30 IST 2016
I have found the formula in the accepted answer will only work in some cases. For example your week starts on Saturday and today is Sunday. To arrive at the first day of the week we walk back 1 day, but the formula cal.get(Calendar.DAY_OF_WEEK) - cal.getFirstDayOfWeek() will give the answer -6. The solution is to use a modulus so the formula wraps around so to speak.
int daysToMoveToStartOfWeek = (
7 +
cal.get(Calendar.DAY_OF_WEEK) -
cal.getFirstDayOfWeek()
)%7;
cal.add(Calendar.DAY_OF_WEEK, -1 * daysToMoveToStartOfWeek);
I want to get the date of the first monday of the current week and the first friday of the current week.
I tried it this way:
Calendar calendarFirstDay = Calendar.getInstance(Locale.GERMANY);
Calendar calendarLastDay = Calendar.getInstance(Locale.GERMANY);
Date now = new Date();
calendarFirstDay.setTime(now);
calendarLastDay.setTime(now);
calendarFirstDay.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
calendarLastDay.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);
MyTextView.setText(calendarFirstDay.get(Calendar.DATE) + "." + calendarFirstDay.get(Calendar.MONTH) + "." + calendarFirstDay.get(Calendar.YEAR) + " - " + calendarLastDay.get(Calendar.DATE) + "." + calendarLastDay.get(Calendar.MONTH) + "." + calendarLastDay.get(Calendar.YEAR));
If I try this script today (Sunday, 26.1.2014), the output is the following:
20.0.2014 - 24.0.2014
Correct would be 20.1.2014 - 24.1.2014
Does somebody knows why my month is zero?
From the JavaDocs:
Field number for get and set indicating the month. This is a calendar-specific value. The first month of the year in the Gregorian and Julian calendars is JANUARY which is 0; the last depends on the number of months in a year.
Thus the first month (January) has a MONTH value of 0, and not 1 (as you'd expect).
There's a much better solution though: use a DateFormat or SimpleDateFormat to format dates as text. That way, you simply don't have to worry about this and let the DateFormat take care of it. For example:
DateFormat myFormat = new SimpleDateFormat("dd.MM.yyyy");
MyTextView.setText(
myFormat.format(calendarFirstDay.getTime()) + " - " +
myFormat.format(calendarLastDay.getTime())
);
As stated in
http://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#set(int,%20int,%20int)
if you use this method, January will be 0 and Decmember will be 11, so you should just add 1 to your month.
EDIT: You are using the get method but it's probably 0-based, too.
The following code does not appear to calculate the correct value for spanNow. Having just run the code today spanYear is correct at 31535999 but for spanNow I have a value 23363788 which appears wrong. The string representation s correctly contains Tue Oct 29 09:56:28 GMT 2013. However 23363788 / 3600 / 24 to get day of year gives 270. The 270's day of the year is Sept 27th, not 29th October. Why the discrepancy and what is the correct way to accurately calculate the number of seconds between two dates?
Thanks Mark
Calendar c = Calendar.getInstance();
int year=c.get(Calendar.YEAR);
GregorianCalendar g = new GregorianCalendar(year,1,1,0,0,0);
Date start = g.getTime();
g = new GregorianCalendar(year,12,31,23,59,59);
Date end = g.getTime();
long spanYear = TimeUnit.MILLISECONDS.toSeconds(end.getTime()-start.getTime());
Date now = new Date();
String s = now.toString();
long spanNow = TimeUnit.MILLISECONDS.toSeconds(now.getTime()-start.getTime());
From the documentation:
month - the value used to set the MONTH calendar field in the calendar. Month value is 0-based. e.g., 0 for January.
so use
GregorianCalendar g = new GregorianCalendar(year,0,1,0,0,0);
I am developing an application in JAVA swing, in that I wanted the date difference from current date like if today is 16/04/2013 then it should return 15/04/2013. I have tried the following code:
Calendar cal = new GregorianCalendar();
Calendar cal2 = new GregorianCalendar();
cal.roll(Calendar.DAY_OF_YEAR, -1);
//if within the first 30 days, need to roll the year as well
if(cal.after(cal2)){
cal.roll(Calendar.YEAR, -1);
}
System.out.println("Year " + cal.get(Calendar.YEAR));
System.out.println("Month " + cal.get(Calendar.MONTH));
System.out.println("Day " + cal.get(Calendar.DAY_OF_MONTH));
In this code I was expecting to get one day back date. But instead I am getting one month back date.
Ex. if today is 16/04/2013, the expected output is 15/04/2013, but I am getting 15/03/2013 ( one month one day back) as an output.
You dont need any manual manipulations, Calendar will do all necessary date arithmetic automatically, simply do this
Calendar cal = new GregorianCalendar();
cal.add(Calendar.DATE, -1);
Note that months in Calendar start from 0 so April is 3
That's a classic example why java.util.Date implementation sucks: Months numeration starts in zero:
0-> January
1-> February
2-> March
3-> April.
What you mean:
new Date(10,1,2013) //10th of January of 2013
What you get: 10th of February of 3983 (1970+2013)
I want to get the last and the first week of a week for a given date.
e.g if the date is 12th October 2011 then I need the dates 10th October 2011 (as the starting date of the week) and 16th october 2011 (as the end date of the week)
Does anyone know how to get these 2 dates using the calender class (java.util.Calendar)
thanks a lot!
Some code how to do it with the Calendar object. I should also mention joda time library as it can help you many of Date/Calendar problems.
Code
public static void main(String[] args) {
// set the date
Calendar cal = Calendar.getInstance();
cal.set(2011, 10 - 1, 12);
// "calculate" the start date of the week
Calendar first = (Calendar) cal.clone();
first.add(Calendar.DAY_OF_WEEK,
first.getFirstDayOfWeek() - first.get(Calendar.DAY_OF_WEEK));
// and add six days to the end date
Calendar last = (Calendar) first.clone();
last.add(Calendar.DAY_OF_YEAR, 6);
// print the result
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(df.format(first.getTime()) + " -> " +
df.format(last.getTime()));
}
This solution works for any locale (first day of week could be Sunday or Monday).
Date date = new Date();
Calendar c = Calendar.getInstance();
c.setTime(date);
int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - c.getFirstDayOfWeek();
c.add(Calendar.DAY_OF_MONTH, -dayOfWeek);
Date weekStart = c.getTime();
// we do not need the same day a week after, that's why use 6, not 7
c.add(Calendar.DAY_OF_MONTH, 6);
Date weekEnd = c.getTime();
For example, today is Jan, 29 2014. For the locale with Sunday as a first day of week you will get:
start: 2014-01-26
end: 2014-02-01
For the locale with Monday as a first day the dates will be:
start: 2014-01-27
end: 2014-02-02
If you want all dates then
first.add(Calendar.DAY_OF_WEEK,first.getFirstDayOfWeek() - first.get(Calendar.DAY_OF_WEEK));
for (int i = 1; i <= 7; i++) {
System.out.println( i+" Day Of that Week is",""+first.getTime());
first.add(Calendar.DAY_OF_WEEK,1);
}
Here is the sample code
public static void main(String[] args) {
Calendar cal = Calendar.getInstance();
cal.set(2016, 2, 15);
{
Calendar startCal = Calendar.getInstance();
startCal.setTimeInMillis(cal.getTimeInMillis());
int dayOfWeek = startCal.get(Calendar.DAY_OF_WEEK);
startCal.set(Calendar.DAY_OF_MONTH,
(startCal.get(Calendar.DAY_OF_MONTH) - dayOfWeek) + 1);
System.out.println("end date : " + startCal.getTime());
}
{
Calendar endCal = Calendar.getInstance();
endCal.setTimeInMillis(cal.getTimeInMillis());
int dayOfWeek = endCal.get(Calendar.DAY_OF_WEEK);
endCal.set(Calendar.DAY_OF_MONTH, endCal.get(Calendar.DAY_OF_MONTH)
+ (7 - dayOfWeek));
System.out.println("start date : " + endCal.getTime());
}
}
which will print
start date : Sun Mar 13 20:30:30 IST 2016
end date : Sat Mar 19 20:30:30 IST 2016
I have found the formula in the accepted answer will only work in some cases. For example your week starts on Saturday and today is Sunday. To arrive at the first day of the week we walk back 1 day, but the formula cal.get(Calendar.DAY_OF_WEEK) - cal.getFirstDayOfWeek() will give the answer -6. The solution is to use a modulus so the formula wraps around so to speak.
int daysToMoveToStartOfWeek = (
7 +
cal.get(Calendar.DAY_OF_WEEK) -
cal.getFirstDayOfWeek()
)%7;
cal.add(Calendar.DAY_OF_WEEK, -1 * daysToMoveToStartOfWeek);