I choose the starting date (example 31/01/2014) and ending date (example 31/12/2014), I insert a record every month. If I get the next month is February 28th, but then I always get 28 though March, April, etc. ..
How can I fix? I hope I explained
SimpleDateFormat sdf1 = new SimpleDateFormat( "yyyy-MM-dd" );
ContentValues cv = new ContentValues();
for(
int i=0;
calendar1.getTime().before(calendar2.getTime());
i++
) {
calendar1.add(Calendar.MONTH, 1);
if (calendar1.getTime().before(calendar2.getTime())) {
String strDate = sdf1.format(calendar1.getTime());
cv.put(etableTable.DATE, strDate);
db.insert(etableTable.TABLE_NAME, null, cv);
...
}
}
Assuming that you speak about class GregorianCalendar - Instead of calendar1.add(Calendar.MONTH, 1) try to also call following method as work-around:
static GregorianCalendar moveToEndOfMonth(GregorianCalendar gcal) {
gcal.add(Calendar.MONTH, 1); // moving to some day of next month
gcal.set(Calendar.DAY_OF_MONTH, 1); // moving to first day of current month
gcal.add(Calendar.DATE, -1); // moving to last day of previous month
}
So your final code should look like:
calendar1.add(Calendar.MONTH, 1);
moveToEndOfMonth(calendar1);
Why? The analysis of #DavidCAdams is right, see his answer.
Where are you creating the calendar objects? Since you are incrementing the MONTH, and it is January 30, you get February 28 for the next month, since next month only has 28 days in it. There is no Feb 30, 2014. Thereafter, when you increment the month, you get March 28, April 28, etc. etc.
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 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 need to find wednesday for the two dates given by the user.
example:
Inputs are:
from date:07-Feb-2013
To date:13-feb-2013
The gap between the from date and To date is 7 days always.
Expected Output:12-feb-2013
public String getAutoDayExpiryDateAndToDate(String instrmentId,String deliveryAutoFromDate)
throws SystemException, FunctionalException,ParseException
{
Calendar calendar = Calendar.getInstance();
calendar.setTime(new Date(deliveryAutoFromDate));
Date fromDate=calendar.getTime();
SimpleDateFormat sf1 = new SimpleDateFormat("dd-MMM-yyyy");
String formatedDate = sf1.format(fromDate);
calendar.add(Calendar.WEEK_OF_MONTH, 1);
calendar.add(Calendar.DAY_OF_WEEK,-1);
Date time = calendar.getTime();
SimpleDateFormat sf = new SimpleDateFormat("dd-MMM-yyyy");
String formatedDate1 = sf.format(time);
}
after these i need to find Wednesday which is present between formatedDate and formatedDate1 .how can i do it??
Use the Calendar class. Set it to the first date, and then check if the current day of the week is Wednesday by calling calendar.get(Calendar.DAY_OF_WEEK). Perform this check in a loop, adding a day to the current date during each iteration. This will never take more than seven steps, so you don't need to do anything fancier than that.
this should find the first Wednesday after (or equal) the given date
GregorianCalendar c = new GregorianCalendar(2013, 1, 7);
if (c.get(Calendar.DAY_OF_WEEK) <= Calendar.WEDNESDAY) {
c.add(Calendar.DAY_OF_YEAR, Calendar.WEDNESDAY - c.get(Calendar.DAY_OF_WEEK));
} else {
c.add(Calendar.DAY_OF_YEAR, 11 - c.get(Calendar.DAY_OF_WEEK));
}
System.out.println(c.getTime());
prints
Wed Feb 13 00:00:00 EET 2013
you can test it to see if it gives you what you want
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);
This question already has answers here:
Closed 13 years ago.
Possible Duplicate:
How to determine the date one day prior to a given date in Java?
If I have a Java.Util.Date object, what is the best way to get an object representing the 24 hours in the past of it?
Using Java 1.6 java.util.Calendar.add:
public static Date subtractDay(Date date) {
Calendar cal = Calendar.getInstance();
cal.setTime(date);
cal.add(Calendar.DAY_OF_MONTH, -1);
return cal.getTime();
}
Others suggest using Joda Time, which is currently JSR 310, and should later be included in Java itself.
The important thing to remember is that the Date class should represent any points in time whilst the Calendar class is used to manipulate those points in time. Last of all, SimpleDateFormat will represent them as Strings.
So, the best way is to use the Calendar class to calculate the new Date for you. This will ensure that any vagaries (Daylight Saving, Leap Years and the like) are accounted for.
I'm assuming that you don't really want to find '24 Hours previous' but actually do want a new Date instance representing 'this time yesterday' - either way, you can ask the Calendar instance for a Date 24Hours prior to another or 1 Day prior.
The Daylight savings is a great example. The UK 'sprang forward' on the 26th March 2009. So, 1 day prior to 3.00a.m. on the 26.Mar.2009 should yield 3.00a.m. 25.Mar.2009 but 24 Hrs prior will yield 2.00a.m.
public class DateTests extends TestCase {
private static String EXPECTED_SUMMER_TIME = "2009.Mar.29 03:00:00";
private static String EXPECTED_SUMMER_TIME_LESS_DAY = "2009.Mar.28 03:00:00";
private static String EXPECTED_SUMMER_TIME_LESS_24_HRS = "2009.Mar.28 02:00:00";
private static String EXPECTED_SUMMER_TIME_LESS_FURTHER_24_HRS = "2009.Mar.27 02:00:00";
public void testSubtractDayOr24Hours() {
SimpleDateFormat formatter = new SimpleDateFormat("yyyy.MMM.dd HH:mm:SS");
Calendar calendar = Calendar.getInstance();
// Create our reference date, 3.00 a.m. on the day the clocks go forward (they 'went' forward at 02.00)
calendar.clear();
calendar.set(2009, 2, 29, 3, 0);
Date summerTime = calendar.getTime(); // Sun Mar 29 03:00:00 BST 2009
String formattedSummerTime = formatter.format(summerTime);
calendar.add(Calendar.DAY_OF_MONTH, -1);
// Our reference date less 'a day'
Date summerTimeLessADay = calendar.getTime(); // Sat Mar 28 03:00:00 GMT 2009
String formattedSummerTimeLessADay = formatter.format(summerTimeLessADay);
// reset the calendar instance to the reference day
calendar.setTime(summerTime);
// Our reference date less '24 hours' (is not quite 24 hours)
calendar.add(Calendar.HOUR, -24);
Date summerTimeLess24Hrs = calendar.getTime(); // Sat Mar 28 02:00:00 GMT 2009
String formattedSummerTimeLess24Hrs = formatter.format(summerTimeLess24Hrs);
// Third date shows that taking a further 24 hours from yields expected result
calendar.add(Calendar.HOUR, -24);
Date summerTimeLessFurther24Hrs = calendar.getTime(); // Fri Mar 27 02:00:00 GMT 2009
String formattedSummerTimeLessFurther24Hrs = formatter.format(summerTimeLessFurther24Hrs);
// reset the calendar once more to the day before
calendar.setTime(summerTimeLess24Hrs);
// Take a 'day' from the Sat will yield the same result as date 03 because Daylight Saving is not a factor
calendar.add(Calendar.DAY_OF_MONTH, -1);
Date summerTimeLessFurtherDay = calendar.getTime(); // Fri Mar 27 02:00:00 GMT 2009
String formattedSummerTimeLessFurtherDay = formatter.format(summerTimeLessFurtherDay);
assert(formattedSummerTime.equals(EXPECTED_SUMMER_TIME));
assert(formattedSummerTimeLessADay.equals(EXPECTED_SUMMER_TIME_LESS_DAY));
assert(formattedSummerTimeLess24Hrs.equals(EXPECTED_SUMMER_TIME_LESS_24_HRS));
assert(formattedSummerTimeLessFurther24Hrs.equals(EXPECTED_SUMMER_TIME_LESS_FURTHER_24_HRS));
// This last test proves that taking 24 hors vs. A Day usually yields the same result
assert(formattedSummerTimeLessFurther24Hrs.equals(formattedSummerTimeLessFurtherDay));
}
}
For testing date functions, wwwdot-timeanddate-dot-com is a great resource.
subtract 1000*60*60*24 from the time and create a new date.
Date yesterday = new Date(d.getTime() - (1000*60*60*24));
int dayInMs = 1000 * 60 * 60 * 24;
Date previousDay = new Date(olddate.getTime() - dayInMs);
Personally if there are a lot of time/date calculations, I'd go with Joda-time.