I am working with the Java Calendar class to do the following:
Set a start date
Set an end date
Any date within that range is a "valid" date
I have this somewhat working, and somewhat not. Please see the code below:
nowCalendar.set(Calendar.DATE, nowCalendar.get(Calendar.DATE) + offset);
int nowDay = nowCalendar.get(Calendar.DATE);
Calendar futureCalendar = Calendar.getInstance();
futureCalendar.set(Calendar.DATE, nowDay + days);
Date now = nowCalendar.getTime();
Date endTime = futureCalendar.getTime();
long now_ms = now.getTime();
long endTime_ms = endTime.getTime();
for (; now_ms < endTime_ms; now_ms += MILLIS_IN_DAY) {
valid_days.addElement(new Date(now_ms));
System.out.println("VALID DAY: " + new Date(now_ms));
}
Basically, I set a "NOW" calendar and a "FUTURE" calendar, and then I compare the two calendars to find the valid days. On my calendar, valid days will be shaded white and invalid days will be shaded gray. You will notice two variables:
offset = three days after the current selected date
days = the number of valid days from the current selected date
This works...EXCEPT when the current selected date is the last day of the month, or two days prior (three all together). I think that its the offset that is definitely screwing it up, but the logic works everywhere else. Any ideas?
Don't fiddle with milliseconds. Clone the nowCalendar, add 1 day to it using Calendar#add() in a loop as long as it does not exceed futureCalendar and get the Date out of it using Calendar#getTime().
Calendar clone = nowCalendar.clone();
while (!clone.after(futureCalendar)) {
validDays.add(clone.getTime());
clone.add(Calendar.DATE, 1);
}
(note that I improved validDays to be a List instead of the legacy Vector)
Use add instead of set in the first line, otherwise the month is not adjusted if you are at the month boundary:
nowCalendar.add(Calendar.DATE, offset);
public boolean isInRange(Date d)
{
Calendar cal = Calendar.getInstance();
cal.setTime(d);
return cal.after(startCal) && cal.before(endCal);
}
Here the startCal is the calendar instance of start time and endCal is end time.
I found the problem:
As soon as I set futureCalendar to be a clone of nowCalendar (plus the additional days), then it started working. Thanks for everyone's suggestions!
Related
I have 2 date object in the database that represent the company's working hours.
I only need the hours but since I have to save date. it appears like this:
Date companyWorkStartHour;
Date companyWorkEndHour;
start hours: 12-12-2001-13:00:00
finish hours: 12-12-2001-18:00:00
I have the timezone of the company and of the user. (my server may be in another timezone).
TimeZone userTimeZone;
TimeZone companyTimeZone;
I need to check if the user's current time (considering his timezone) is within the company working hours (considering the company's time zone).
How can I do it? I am struggling for over a week with Java calendar and with no success!
The java.util.Date class is a container that holds a number of milliseconds since 1 January 1970, 00:00:00 UTC. Note that class Date doesn't know anyting about timezones. Use class Calendar if you need to work with timezones. (edit 19-Jan-2017: if you are using Java 8, use the new date and time API in package java.time).
Class Date is not really suited for holding an hour number (for example 13:00 or 18:00) without a date. It's simply not made for that purpose, so if you try to use it like that, as you seem to be doing, you'll run into a number of problems and your solution won't be elegant.
If you forget about using class Date to store the working hours and just use integers, this will be much simpler:
Date userDate = ...;
TimeZone userTimeZone = ...;
int companyWorkStartHour = 13;
int companyWorkEndHour = 18;
Calendar cal = Calendar.getInstance();
cal.setTime(userDate);
cal.setTimeZone(userTimeZone);
int hour = cal.get(Calendar.HOUR_OF_DAY);
boolean withinCompanyHours = (hour >= companyWorkStartHour && hour < companyWorkEndHour);
If you also want to take minutes (not just hours) into account, you could do something like this:
int companyWorkStart = 1300;
int companyWorkEnd = 1830;
int time = cal.get(Calendar.HOUR_OF_DAY) * 100 + cal.get(Calendar.MINUTE);
boolean withinCompanyHours = (time >= companyWorkStart && time < companyWorkEnd);
Try something like this:
Calendar companyWorkStart = new GregorianCalendar(companyTimeZone);
companyWorkStart.setTime(companyWorkStartHour);
Calendar companyWorkEnd = new GregorianCalendar(companyTimeZone);
companyWorkEnd.setTime(companyWorkEndHour);
Calendar user = new GregorianCalendar(userTimeZone);
user.setTime(userTime);
if(user.compareTo(companyWorkStart)>=0 && user.compareTo(companyWorkEnd)<=0) {
...
}
I haven't tried the Joda library. This code should work.
public boolean checkUserTimeZoneOverLaps(TimeZone companyTimeZone,
TimeZone userTimeZone, Date companyWorkStartHour,
Date companyWorkEndHour, Date userCurrentDate) {
Calendar userCurrentTime = Calendar.getInstance(userTimeZone);
userCurrentTime.setTime(userCurrentDate);
int year = userCurrentTime.get(Calendar.YEAR);
int month = userCurrentTime.get(Calendar.MONTH);
int day = userCurrentTime.get(Calendar.DAY_OF_MONTH);
Calendar startTime = Calendar.getInstance(companyTimeZone);
startTime.setTime(companyWorkStartHour);
startTime.set(Calendar.YEAR, year);
startTime.set(Calendar.MONTH, month);
startTime.set(Calendar.DAY_OF_MONTH, day);
Calendar endTime = Calendar.getInstance(companyTimeZone);
endTime.setTime(companyWorkEndHour);
endTime.set(Calendar.YEAR, year);
endTime.set(Calendar.MONTH, month);
endTime.set(Calendar.DAY_OF_MONTH, day);
if (userCurrentTime.after(startTime) && userCurrentTime.before(endTime)) {
return true;
}
return false;
}
EDIT
Updated the code to reflect Bruno's comments. Shouldn't be taking the dates of the company work timings.
Hey I am not sure how you would do this using the Java calendar but I would highly recommend using the Joda Time package. It's a much simpler system to use and it gives you direct methods to extracts all subcomponents of data and time and even just to create simple time objects without the date involved. Then I imagine it would be a matter of comparing the 2 timezone differences and subtracting the difference from the JodaTime object.
I am trying to subtract days from the current date using the java.util.Calendar object. My problem here is the days to subtract can be positive or negative. My code is as follows
public class Test {
public static void main(String[] args) {
int pastValidationDays=2;
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH, - pastValidationDays);
}
}
As per the above code if the date is 20/1/2015 it will give me 18/1/2015
Now say if the pastValidationDays= -2(negative value) then also it should subtract from the current date. As per the above code if i say
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH, - pastValidationDays);
then it is adding up the days instead of subtracting. Say if the current date 20/1/2015 it is giving me 22/1/2015. But in this case as well i need the date as 18/1/2015.
One of the way i am doing is as below
if (pastValidationDays < 0){
calendar.add(Calendar.DAY_OF_MONTH, pastValidationDays);
}else{
calendar.add(Calendar.DAY_OF_MONTH, -pastValidationDays);
}
Is this a good approach or can it be done this way
calendar.add(Calendar.DAY_OF_MONTH, - Math.abs(pastValidationDays));
I want to subtract the days using calendar object only. I do not want to use JODA time and other objects. Please suggest other approaches if any. Thanks in advance
This is my first question, so please be gentle with me! I am having a problem with some pre-existing java code.
It is pretty simple, you pass it two dates in the format "2013-10-31", it then calculates the ms difference between the two values and then does some more calculations after that. The problem is that every now and again, even though two different dates are passed, they both have the same millisecond value. An example of this is if you pass "2013-10-31" and "2013-11-01", it returns the difference as 0. The ms values both being "1385856000000".
Code is:
public int getTotalStartEndTime( java.sql.Date startdate, java.sql.Date enddate, java.sql.Time starttime, java.sql.Time endtime )
{
if(startdate != null & enddate != null && starttime !=null && endtime!= null){
Calendar calendar1 = Calendar.getInstance();
Calendar calendar2 = Calendar.getInstance();
int styr = Integer.parseInt(startdate.toString().substring(0,startdate.toString().indexOf("-")),10);
int stmm = Integer.parseInt(startdate.toString().substring(startdate.toString().indexOf("-")+1,startdate.toString().lastIndexOf("-")),10);
int stdd = Integer.parseInt(startdate.toString().substring(startdate.toString().lastIndexOf("-")+1),10);
int enyr = Integer.parseInt(enddate.toString().substring(0,enddate.toString().indexOf("-")),10);
int enmm = Integer.parseInt(enddate.toString().substring(enddate.toString().indexOf("-")+1,enddate.toString().lastIndexOf("-")),10);
int endd = Integer.parseInt(enddate.toString().substring(enddate.toString().lastIndexOf("-")+1),10);
//calendar1.set(styr, stmm, stdd);
calendar1.set(Calendar.YEAR, styr);
calendar1.set(Calendar.MONTH, stmm);
calendar1.set(Calendar.DAY_OF_MONTH, stdd);
calendar1.set(Calendar.HOUR, 0);
calendar1.set(Calendar.MINUTE, 0);
calendar1.set(Calendar.SECOND, 0);
calendar1.set(Calendar.MILLISECOND,0);
//calendar2.set(enyr, enmm, endd);
calendar2.set(Calendar.YEAR, enyr);
calendar2.set(Calendar.MONTH, enmm);
calendar2.set(Calendar.DAY_OF_MONTH, endd);
calendar2.set(Calendar.HOUR, 0);
calendar2.set(Calendar.MINUTE, 0);
calendar2.set(Calendar.SECOND, 0);
calendar2.set(Calendar.MILLISECOND,0);
long milliseconds1 = calendar1.getTimeInMillis();
long milliseconds2 = calendar2.getTimeInMillis();
long diff = milliseconds2 - milliseconds1;
Any help would be greatly appreciated, as I cannot work out what is happening!
calendar month is 0-11, in your code, you parsing date from string and month 10 is converted to november, which has not 31 days and set to first december.
As it has been said, MONTH is 0-11.
Your code didn't throw an exception since the default value of lenient is true.
You should set it to false (unless you explicitly want this behavior) to detect this kind of situation more easily :
calendar1.setLenient(false);
calendar2.setLenient(false);
It's not actually answering your question, but if all you need is the value of diff, there is no need to work with Calendar instances, but you can replace your code entirely with:
long diff = enddate.getTime() - startdate.getTime();
If you actually need the Calendar objects for other operations, there is still no need to parse the string representation of the dates, you can simply set the Calendar to the Date value with one operation:
Calendar calendar1 = Calendar.getInstance();
calendar1.setTimeInMillis(startdate.getTime());
I've read around and basically I've figured out that the Calendar object is capable of adding 1 month to a date specified by using something like:
Calendar cal = Calendar.getInstance();
cal.add(Calendar.MONTH, 1);
Although I don't like its behavior whenever the date is on either the 30 or 31. If ever I add 1 month to 01/31/2012, the output becomes 02/29/2012. When I add 1 more month, it becomes 03/29/2012.
Is there anyway I can force 02/29/2012 to become 03/01/2012 automatically?
Basically this is what I want to happen:
Default date: 01/31/2012
Add 1 month: 03/01/2012
Add 1 more month: 03/31/2012
What you are asking for is some implicit knowledge that if the starting date is the last day of the month, and you add 1 month, the result should be the last day of the following month. I.e. the property "last-day-of-month" should be sticky.
This is not directly available in Java's Calendar, but one possible solution is to use Calendar.getActualMaximum(Calendar.DAY_OF_MONTH) to reset the day after incrementing the month.
Calendar cal = ...;
cal.add(Calendar.MONTH,1);
cal.set(Calendar.DAY_OF_MONTH,cal.getActualMaximum(Calendar.DAY_OF_MONTH));
You could even subclass GregorianCalendar and add a method
public Calendar endOfNextMonth() { ... }
to encapsulate the operation.
Well for add 30 days you can do something like this:
public static java.sql.Date sumarFechasDias(java.sql.Date fch, int days) {
Calendar cal = new GregorianCalendar();
cal.setTimeInMillis(fch.getTime());
cal.add(Calendar.DATE, days);
return new java.sql.Date(cal.getTimeInMillis());
}
if days=30, it will return your date with 30 days added.
It looks like you want the calendar to roll up to the beginning of the next month if the date of the next month is smaller than the date of the month before it. Here's how we'd do that:
Calendar cal = Calendar.getInstance();
int oldDay = cal.get(DAY_OF_MONTH);
cal.add(Calendar.MONTH, 1);
// If the old DAY_OF_MONTH was larger than our new one, then
// roll over to the beginning of the next month.
if(oldDay > cal.get(DAY_OF_MONTH){
cal.add(Calendar.MONTH, 1);
cal.set(Calendar.DAY, 1);
}
I have faced the same problem many times.
The Same Problem was With This Question and Got Solution Like the Same,
How to compare known hours ad current hour in android?
Problem :
When I use Calendar calCurr = Calendar.getInstance(); to get the Calendar object of current date and time, It always return me wrong.
I have put logs and checked it and to make it correct I had to add in years and months and then I got the correct object for Current Date and Time.
See My Example :
Calendar calCurr = Calendar.getInstance();
Log.i("Time in mili of Current - Normal", ""+calCurr.getTimeInMillis());
// see what it gives? dont know why?
Date date = new Date();
calCurr.set(date.getYear()+1900, date.getMonth()+1, date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds());
// so added one month to it
Log.i("Time in mili of Current - after update", ""+calCurr.getTimeInMillis());
// now get correct
Question :
Why it's giving the wrong output?
Is it a bug in there or My concept about the Calendar class is wrong?
tell me what should have been done
for that?
It works perfectly as expected if you change to getDate() it outputs :
Time in mili of Current - Normal Wed Apr 04 11:34:34 BST 2012
Time in mili of Current - after update Fri May 04 11:34:34 BST 2012
What do you expect ? And in milleseconds it also equals 30 days :
Time in mili of Current - Normal 1333535834557
Time in mili of Current - after update 1336127834557
and the calculation is (difference, divided by milliseconds in a day) :
1336127834557 - 1333535834557 = 2 592 000 000
2592000000 / 86400000 = 30
And todays date in milliseconds after 1970 is 1333536754 ... which fits, I don't see a problem.
EDIT
Your Problem is you are setting Month like 3 for march...there you need to set 2..cause months are indexed from 0 to 11.
Do not use date.getXXX(). Do not use any setter or getter except Date.getTime(). They are all deprecated. Using them would cause unexpected results.
If you call Calendar.getInstance(), it is already set to the current date. If you want to set or add days, months, whatever, set them on the calendar.
E.g. calCurr.set(Calendar.MONTH,2) or calCurr.add(Calendar.DAY,1).
It is NOT a bug, the Calendar is returning what it should (at least here it is).
Calendar calCurr = Calendar.getInstance();
Log.i("Time in mili of Current - Normal", ""+calCurr.getTimeInMillis());
// see what it gives? dont know why?
I got 1333546375707 milliseconds, which is the correct value (also calculated by hand).
Which value are you expecting here? How you know it is wrong?
Date date = new Date();
calCurr.set(date.getYear()+1900, date.getMonth()+1, date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds());
// so added one month to it
Why adding ONE to the month? Month of both Date and Calendar are zero-based - no need to add 1.
EDIT
Calculating by hand (approximated):
2012 - 42 years * 365.24 days/year * 86400 seconds/day
April - (31 + 29 + 31) days * 86400
4th - 3 days * 86400
13:30 - 13.5 hours * 3600 seconds/hour
====================
1333553112 seconds
Calendar months are zero-indexed. So when want to set for March its 2 not 3
Also, Don't set year, month and date from the Date object. If you must initialise a Calendar to a date, do it like this:
Calendar cal = Calendar.getInstance();
cal.setTime(date);
be aware that your Date object might be a different locale to what you think it is.
When Calendar object is created by using Calendar.getInstance() the instance variable "time" in the Calendar object is set and this value will get changed only if you use
Calendar.setTimeInMillis() function.
Code snippet from Calendar object:
public long getTimeInMillis() {
if (!isTimeSet) {
updateTime();
}
return time;
}
Here "isTimeSet" will become "true" when Calendar.getInstance() is called and it returns "time" every time without updating the time.
This is the reason you get the same value of time every time you call
calCurr.getTimeInMillis();
Hope this helps.
It's the weird implementation of Calendar.
For some reasons January is month 0, and years are not very logical as well.
I recommend Joda time library.
We are using below lines of code for finding current date and time It's working fine our side.
java.util.Calendar calc = java.util.Calendar.getInstance();
int day = calc.get(java.util.Calendar.DATE);
int month = calc.get(java.util.Calendar.MONTH)+1;
int year = calc.get(java.util.Calendar.YEAR);
String dayStr,monthStr;
if(day<10){
dayStr = "0"+day;
}else{
dayStr = ""+day;
}
if(month<10){
monthStr = "0"+month;
}else{
monthStr = ""+month;
}
/*String currentdate = monthStr+"/"+dayStr+"/"+year+" ";*/
String currentdate = dayStr+"/"+monthStr+"/"+year+" ";
/*String currenttime = currentdate + String.valueOf(calc.get(java.util.Calendar.HOUR_OF_DAY))+ ":"+
String.valueOf(calc.get(java.util.Calendar.MINUTE))+":"+String.valueOf(calc.get(java.util.Calendar.SECOND));*/
return currentdate;
Java Date Based API is not properly designed.
in future versions I think some problems of The API are planned to address.
I would recommend to use JodaTime.