This question already has answers here:
Get yesterday's date using Date [duplicate]
(8 answers)
Closed 8 years ago.
I've got an object with a field timestamp with type java.sql.Timestamp;.
And I need to get objects with yesterday date from a collection.
How to get them?
I mean I need something like this
for(int i = 0; i < items.size(); i++) {
(if the items.get(i).date == yesterday_date)
(get object)
}
You can get yesterday's Date by following approach Answered by Jiger Joshi.
And by using new Timestamp(java.util.Date) you can get yesterday's timestamp, you should use Timestamp#equals to equaling two different timestamp.
if (items.get(i).date.equals(getYesterdaytimestamp())){
...
}
And there are something which you must consider while implementing this. Calender#getTime which returns Date object and date object contains date with time, so in that case your equaling date or timestamp must be exactly equals with yesterday's date and time.
If requirement is, it needs to equal just yesterday no not where time is not considerable fact. In that case you need to equals two timestamp after discarding time part.
if (equalsWithYesterday(items.get(i).date)){
...
}
...
public boolean equalsWithYesterday(Timestamp st){
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd"); // Time part has discarded
Calendar cal = Calendar.getInstance();
cal.add(Calendar.DATE, -1);
Date yesterday = dateFormat.parse(dateFormat.format(cal.getTime())); // get yesterday's Date without time part
Date srcDate = new Date(st);
Date srcDateWithoutTime =dateFormat.parse(dateFormat.format(srcDate));
return yesterday.equals(srcDateWithoutTime ); // checks src date equals yesterday.
}
You can convert the timestamp object to date object like this:
Date date = new Date(items.get(i).getTime());
or you can simply use method Timestamp#compareTo(Date o)
items.get(i).compareTo(yesterday_date);
I hope you are not interested to compare the time?
Simply use Calendar class to extract the day, month, year etc. from the date and simply compare it.
Use Calendar#get() method to get the specific field from the date object.
How to subtract one day from the current date?
// get Calendar with current date
Calendar cal = Calendar.getInstance();
// get yesterday's date
cal.add(Calendar.DATE, -1);
// get components of yesterday's date
int month = cal.get(Calendar.MONTH) + 1; // 0 for January, 1 for Feb and so on
int day = cal.get(Calendar.DATE);
int year = cal.get(Calendar.YEAR);
// get yesterday's date in milliseconds
long lMillis = cal.getTime().getTime();
Related
This question already has answers here:
Java Calendar adds a random number of milliseconds?
(4 answers)
Closed 4 years ago.
I'm wondering why I always get a difference between this date in milliseconds.
Any idea ?
Here is the output :
date = 1572794103293 ms
date2 = 1572794103341 ms
date3 = 1572794103341 ms
date4 = 1572794103341 ms
and here is the code :
Date date = createDate();
Date date2 = createDate();
Date date3 = createDate();
Date date4 = createDate();
System.out.println(date.getTime());
System.out.println(date2.getTime());
System.out.println(date3.getTime());
System.out.println(date4.getTime());
private static Date createDate() {
Calendar c = GregorianCalendar.getInstance();
c.set(2019, Calendar.NOVEMBER, 03, 16, 15, 03);
return c.getTime();
}
In the documentation of Calendar.set, it is said :
Sets the values for the fields YEAR, MONTH, DAY_OF_MONTH, HOUR, MINUTE, and SECOND. Previous values of other fields are retained. If this is not desired, call clear() first.
The reason is that not all fields are set with this method, in you case, you don't have MILLISECOND set. So it keep the value when the instance was created.
The call of Calendar.clear will
Sets all the calendar field values and the time value (millisecond offset from the Epoch) of this Calendar undefined.
A quick example :
Calendar c = GregorianCalendar.getInstance();
c.clear();
c.set(2019, Calendar.NOVEMBER, 03, 16, 15, 03);
System.out.println(c.getTimeInMillis());
1572794103000
Milliseconds being undefined will give 0
In addition to the comments and AxelH's answer mentioning the fact that the milliseconds of a Calendar instance aren't changed by Calendar.set, there is still the curiosity that you get the same value for date2, date3 and date4, but a different value for date.
This is because the very first time you call createDate() the JVM has to initialize the Date class, which happens after Calendar c was initialized.
Thus on the first call c.getTime() needs more time than on the consecutive calls, which you can see as the difference between the value of date and the other 3 instances.
If you add a call to new Date() before the first call to createDate(), the difference between each value should be the same.
Please note that this does not fix your issue, it just hides it if your machine is fast enough. It's merely an explanation for the particular values you get.
This question already has answers here:
Comparing two java.util.Dates to see if they are in the same day
(14 answers)
How to know if a Date is within the same day of other date [duplicate]
(2 answers)
Closed 6 years ago.
According to Java API public boolean before(Date when)
true if and only if the instant of time represented by this Date
object is strictly earlier than the instant represented by when; false
otherwise.
Now I have to check if date input by user is greater than current date then only it will accept the input otherwise throw exception so i tried below
if(userInputDate.before(new Date())){
throw new Exception("Some Message");
}
But if both date are same then also it going to inside if statement .Do it mean it will calculate time and then check rather than comparing date? If yes how to resolve my issue ?
Can any one tell me how to add check for this?
The method before in the class Date is comparing the millisecond between the dates, so it's not comparing just the day, it is comparing the instant of time.
You could create a method to check if the dates are not in the same day and the first date is before the second one
public static boolean isBeforeDate(Date date1, Date date2) {
SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
boolean areTheSameDay = fmt.format(date1).equals(fmt.format(date2));
return !areTheSameDay && date1.before(date2);
}
If you can use the new time api In Java8 instead of the old Date class, you can use the class LocalDate and the method compareTo:
boolean isBefore = myLocalDate.compareTo(myOtherLocalDate) < 0
All methods on java.util.Date that allow one to separate the time of day from the day of the year are deprecated. Therefore it is better to use java.util.Calendar. Additionally one should consider that there is typically one hour in each year that is in two days when summer time ends.
Here are two ways you can do it:
public static boolean isBeforeDay(Date date1, Date date2) {
// convert date1 to noon on the same day
Calendar day1 = Calendar.getInstance(TimeZone.getDefault());
day1.setTime(date1);
day1.set(Calendar.HOUR_OF_DAY, 12);
day1.set(Calendar.MINUTE, 0);
day1.set(Calendar.SECOND, 0);
day1.set(Calendar.MILLISECOND, 0);
// convert date2 to noon on the same day
Calendar day2 = Calendar.getInstance(TimeZone.getDefault());
day2.setTime(date2);
day2.set(Calendar.HOUR_OF_DAY, 12);
day2.set(Calendar.MINUTE, 0);
day2.set(Calendar.SECOND, 0);
day2.set(Calendar.MILLISECOND, 0);
return day1.before(day2);
}
public static boolean isBeforeDay(Date date1, Date date2) {
// get yyyymmdd value from date1
Calendar day1 = Calendar.getInstance(TimeZone.getDefault());
day1.setTime(date1);
int ymd1 = 10000*day1.get(Calendar.YEAR) + 100*day1.get(Calendar.MONTH) + day1.get(Calendar.DAY_OF_MONTH);
// get yyyymmdd value from date2
Calendar day2 = Calendar.getInstance(TimeZone.getDefault());
day2.setTime(date2);
int ymd2 = 10000*day2.get(Calendar.YEAR) + 100*day2.get(Calendar.MONTH) + day2.get(Calendar.DAY_OF_MONTH);
return ymd1 < ymd2;
}
This question already has answers here:
How can I determine if a date is between two dates in Java? [duplicate]
(11 answers)
Closed 9 years ago.
I'm trying to write a schedule program in Java and I need to figure out what time it is, and whether the current time is in between two set times. Figuring out the current time is pretty simple, but do you have any suggestions for figuring out whether it is between two times of day. For example, it is 9:33 AM on a Thursday. So I would need to figure out which scheduled section of the week that time corresponds to. How would I go about comparing the time to set periods during the week, for example an Array of sectioned times during a week such as {Monday from 9-10 AM, Tuesday from 3-4 PM, Thursday from 8-11 AM}, and seeing which section of time the current time falls between?
An efficient way to find which period any date lies within would be to have a class;
public class TimePeriod implements Comparable<TimePeriod>{
Date start;
Date end;
//Constructor, getters, setters
boolean isIn(Date date) {
return date.after(start) && date.before(end);
}
public int compareTo(TimePeriod other) {
return start.compareTo(other.start);
}
}
..and then create a sorted list of TimePeriod where you can perform a binary search.
edit:
This might make the binary search easier;
int check(Date date) {
if (isIn(date)) {
return 0;
} else if (start.after(date)) {
return -1;
} else if (end.before(date)) {
return 1;
} else {
throw new IllegalStateException("Time has gone badly wrong");
}
}
If you're using Date Class, you could do it like this
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm");
Date before = sdf.parse("07/05/2012 08:00");
Date after = sdf.parse("07/05/2012 08:30");
Date toCheck = sdf.parse("07/05/2012 08:15");
//is toCheck between the two?
boolean isAvailable = (before.getTime() < toCheck.getTime()) && after.getTime() > toCheck.getTime();
EDITED
As suggested by Jonathan Drapeau you could also use compareTo.
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy hh:mm");
Date before = sdf.parse("07/05/2012 08:00");
Date after = sdf.parse("07/05/2012 08:30");
Date toCheck = sdf.parse("07/05/2012 08:15");
//is toCheck between the two?
if you want to include the "initial" and "final" date range
boolean isAvailable = before.compareTo(toCheck) >= 0 && after.compareTo(toCheck) <= 0
if you want to exclude the "initial" and "final" date range
boolean isAvailable = before.compareTo(toCheck) > 0 && after.compareTo(toCheck) < 0
You could use it too on Calendar class.
Anyway, i highly recommend you to use Calendar. It's a way precise class
you could check it like this:
Calendar cal1 = Calendar.getInstance(); // for example 12:00:00
Calendar cal2 = Calendar.getInstance(); // for exmaple 12:30:00
Calendar userTime = Calendar.getInstance(); // time to test: 12:15:00
if(user.after(cal1)&& user.before(cal2)){
//...
}
And to initialize and set times to Calendar, check this:
http://www.tutorialspoint.com/java/util/calendar_settime.htm
I would suggest using the Epoch time.
For a definition of Epoch time: http://en.wikipedia.org/wiki/Epoch_time
Basically, its a number of seconds after a specific date, i believe in 1989. If you translate the 3 times (the current time and the 2 times to compare to) in epoch time you can just use > < = etc.
For information on getting epoch time, Try here (has many languages): http://shafiqissani.wordpress.com/2010/09/30/how-to-get-the-current-epoch-time-unix-timestamp/
Unfortunately, my java is lacking or I'd give you some code :)
Edit:
Java epoch time code:
long epoch = System.currentTimeMillis()/1000;
Because my Java is bad and I don't have an interpreter where I am, I can only suggest using this site to help convert the other dates to epoch time: http://www.epochconverter.com/
There is before(Date) and after(Date) method in Date Class.
secondDate.before(firstDate)
If you use Calendar class, it has explicit before() and after() methods:
Calendar startDate = ...
Calendar endData = ...
isBetween = currentDate.after(startDate) && currentDate.before(endDate);
The date is selected by the user using a drop down for year, month and day. I have to compare the user entered date with today's date. Basically see if they are the same date. For example
the user entered 02/16/2012. And if today is 02/16/2012 then I have to display a message. How do I do it?
I tried using milliseconds but that gives out wrong results.
And what kind of object are you getting back? String, Calendar, Date? You can get that string and compare it, at least that you think you'll have problems with order YYYY MM DD /// DD MM YYY in that case I suggest to create a custom string based on your spec YYYYMMDD and then compare them.
Date d1 = new Date();
Date d2 = new Date();
String day1 = d1.getYear()+"/"+d1.getMonth()+"/"+d1.getDate();
String day2 = d2.getYear()+"/"+d2.getMonth()+"/"+d2.getDate();
if(day1.equals(day2)){
System.out.println("Same day");
}
Dates in java are moments in time, with a resolution of "to the millisecond". To compare two dates effectively, you need to first set both dates to the "same time" in hours, minutes, seconds, and milliseconds. All of the "setTime" methods in a java.util.Date are depricated, because they don't function correctly for the internationalization and localization concerns.
To "fix" this, a new class was introduced GregorianCalendar
GregorianCalendar cal1 = new GregorianCalendar(2012, 11, 17);
GregorianCalendar cal2 = new GregorianCalendar(2012, 11, 17);
return cal1.equals(cal2); // will return true
The reason that GregorianCalendar works is related to the hours, minutes, seconds, and milliseconds being initialized to zero in the year, month, day constructor. You can attempt to approximate such with java.util.Date by using deprecated methods like setHours(0); however, eventually this will fail due to a lack of setMillis(0). This means that to use the Date format, you need to grab the milliseconds and perform some integer math to set the milliseconds to zero.
date1.setHours(0);
date1.setMinutes(0);
date1.setSeconds(0);
date1.setTime((date1.getTime() / 1000L) * 1000L);
date2.setHours(0);
date2.setMinutes(0);
date2.setSeconds(0);
date2.setTime((date2.getTime() / 1000L) * 1000L);
return date1.equals(date2); // now should do a calendar date only match
Trust me, just use the Calendar / GregorianCalendar class, it's the way forward (until Java adopts something more sophisticated, like joda time.
There is two way you can do it. first one is format both the date in same date format or handle date in string format.
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
String date1 = sdf.format(selectedDate);
String date2 = sdf.format(compareDate);
if(date1.equals(date2)){
}else{
}
Or
Calendar toDate = Calendar.getInstance();
Calendar nowDate = Calendar.getInstance();
toDate.set(<set-year>,<set-month>,<set-date->);
if(!toDate.before(nowDate))
//display your report
else
// don't display the report
Above answers are correct but consider using JodaTime - its much simpler and intuitive API.
You could set DateTime using with* methods and compare them.
Look at this answer
This is a really simple request, but I am not quite sure the easiest/most efficient way of generating these two values.
I need to write a script that will check whether a given value is between two values. I am well aware of how this is done in SQL.
The way I need the values is somethign similar to the following.
Date testValue = new Date() //This represents the value we are testing
Date beginningOfDay = .... //This value would represent the date for
testValue at 12:00am
Date endOfDay = ... //This value would represent the date for
testValue at 11:59:59pm
Again, the Java Date() type may not be the best practice to do something like this. In the end I just need to generate three values that I can say
if testValue is after beginningOfDay && testValue is before endOfDay
//do logic
Personally I use the Calendar object for this. For example:
Date testDate = ??? //Replace with whatever source you are using
Calendar testDateCalendar = Calendar.getInstance();
testDateCalendar.setTime(testDate);
Date today = new Date();
Calendar endOfDay = Calendar.getInstance(); //Initiates to current time
endOfDay.setTime(today);
endOfDay.set(Calendar.HOUR_OF_DAY, 23);
endOfDay.set(Calendar.MINUTE, 59);
endOfDay.set(Calendar.SECOND, 59);
Calendar startOfDay = Calendar.getInstance();
startOfDay.setTime(today);
startOfDay.set(Calendar.HOUR_OF_DAY, 0);
startOfDay.set(Calendar.MINUTE, 0);
startOfDay.set(Calendar.SECOND, 0);
if (startOfDay.before(testDateCalendar) && endOfDay.after(testDateCalendar))
{
//Whatever
} else {
//Failure
}
You can use a calendar object to do this and by the way, the way you did the bounds check in your question is wrong (your date can match the before/after dates and still be considered in range). The following shows whether a date falls on a certain day of the year. It assumes that the timezones for the dateTime to check and the day are equal and that no time adjustments took place:
Date dateTime=...
Date day=...
// This is the date we're going to do a range check on
Calendar calDateTime=Calendar.getInstance();
calDateTime.setTime(dateTime);
// This is the day from which we will get the month/day/year to which
// we will compare it
Calendar calDay=Calendar.getInstance();
calDay.setTime(day);
// Calculate the start of day time
Calendar beginningOfDay=Calendar.getInstance();
beginningOfDay.set(calDay.Get(Calendar.YEAR),
calDay.Get(Calendar.MONTH),
calDay.Get(Calendar.DAY_OF_MONTH),
0, // hours
0, // minutes
0); // seconds
// Calculate the end of day time
Calendar endOfDay=Calendar.getInstance();
endOfDay.set(calDay.Get(Calendar.YEAR),
calDay.Get(Calendar.MONTH),
calDay.Get(Calendar.DAY_OF_MONTH),
23, // hours
59, // minutes
59); // seconds
// Now, to test your date.
// Note: You forgot about the possibility of your test date matching either
// the beginning of the day or the end of the day. The accepted answer
// got this range check wrong, as well.
if ((beginningOfDay.before(calDateTime) && endOfDay.after(calDateTime)) ||
beginningOfDay.equals(calDateTime) || endOfDay.equals(calDateTime))
{
// Date is in range...
}
This can be further simplified to:
Date dateTime=...
Date day=...
// This is the date we're going to do a range check on
Calendar calDateTime=Calendar.getInstance();
calDateTime.setTime(dateTime);
// This is the day from which we will get the month/day/year to which
// we will compare it
Calendar calDay=Calendar.getInstance();
calDay.setTime(day);
if (calDateTime.get(YEAR)==calDay.get(YEAR) &&
calDateTime.get(MONTH)==calDay.get(MONTH) &&
calDateTime.get(DAY_OF_YEAR)==calDay.get(DAY_OF_YEAR))
{
// Date is in range
}
Here's something I've used in my own code to determine if a file was modified on a certain day. Like the other answers in this thread, I used the Calendar.
// Get modified date of the current file
// and today's date
Calendar today = Calendar.getInstance();
Calendar modDate = Calendar.getInstance();
Date date = new Date(file.lastModified());
modDate.setTime(date);
// Convert dates to integers
int modDay = modDate.get(Calendar.DAY_OF_YEAR);
int todayDay = today.get(Calendar.DAY_OF_YEAR);
if (modDay == todayDay) {
// Do stuff
}
This might be closer to what you are looking for since you only need to see if the event falls on a certain day.