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
Related
I want to compare time difference in hours. Based on current time and time I get from database.
DateFormat sdf = new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss”);
Date date = new Date();
Logger.info(“current time is”,sdf.format(date));
// gives date in 2019-11-06 17:03:54
// dB gives following record
Date successDate = loader.getLastSuccess();
// gives date in 2019-10-31T:56:08.066+0000
Both formats are different how to get the time difference any suggestion experts
You can use the java-8 date API Duration to get the duration between both the dates
long hours = Duration.between(date1.toInstant(), date2.toInstant()).toHours();
Note : It can return negative value also here
the number of hours in the duration, may be negative
public int getHours() on util.Date is deprecated, so convert them to Instant and use Duration.between and also i will suggest to use java-8 Date API instead of older version Date
If you want difference in hours as double, you can do this;
Date your_date = loader.getLastSuccess();
Date currentDate = new Date();
double hourdifference = (currentDate.getTime() - your_date.getTime()) / 3600000.0;
You can get long or int, just change 3600000.0 to 3600000, and make the variable int or long
This question already has answers here:
How to get the first day of the current week and month?
(15 answers)
Closed 6 years ago.
I would like to fetch the first date of a week.
My input is going to be a String type like 07/26/2014".
I need to get the first date of week in which the above date(07/26/2014) falls.
I need output date in MM/dd/YYYY format .
basically I need output as 07/21/2014.
Please give me the java program. I have done upto this
SimpleDateFormat formatter1 = new SimpleDateFormat("MM/dd/yy");
String date ="07/26/2014";
Date Currentdate = formatter1.parse(date);
int currentday=Currentdate.getDay();
Calendar calendar = Calendar.getInstance();
calendar.setTime(Currentdate);
int startDay=currentday-calendar.getFirstDayOfWeek();
Currentdate.setDate(contacteddate.getDate()-startDay);
System.out.println(contacteddate.getDate());
}
The above code only gives me the date.. I need date along with month and year in "MM/dd/YYYY"
Please help
I would do it this way
Calendar calendar = Calendar.getInstance();
calendar.setTime(Currentdate);
calendar.set(Calendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());
After setting time to Calendar
Calendar calendar = Calendar.getInstance();
calendar.setTime(Currentdate);
use
calendar.set(Calendar.DAY_OF_WEEK, 1)
and then
simpleFormat.format(calendar.getTime());
This will help you.
// Get calendar set to current date and time
Calendar c = Calendar.getInstance();
// Set the calendar to monday of the current week
c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
// Print dates of the current week starting on Monday
DateFormat df = new SimpleDateFormat("EEE dd/MM/yyyy");
for (int i = 0; i < 1; i++) {
System.out.println(df.format(c.getTime()));
c.add(Calendar.DATE, 1);
}
The problem with all presented solutions so far is not to specify what exactly the week definition is. Week definitions are either technically specified like in ISO-8601-standard (Monday as first day of week and first calendar week of year containing at least four days), or they use localized rules (for example in US a week begins by Sunday!).
Due to the requirement that the OP wants "07/21/2014" as first day of week around "07/26/2014" it seems that ISO-8601 is what the OP really wants. But code like
Calendar calendar = Calendar.getInstance();
c.set(Calendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());
...
will not work in a country like US or an application server located in US. Counter example:
// simulating a US-located application server where this code is running
GregorianCalendar calendar = new GregorianCalendar(Locale.US);
calendar.set(2014, Calendar.JULY, 26);
calendar.getTime(); // avoid ugly side effects in calendar date handling
calendar.set(Calendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek());
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
System.out.println(sdf.format(calendar.getTime())); // output: 2014-07-20
If the OP changes the choosen locale to let's say Locale.FRANCE (applying ISO-rules) then the OP can achieve his goal using the traditional Java-date-and-time-library.
It should be noted however that week handling using the java.util.Calendar-stuff is often confusing and hard. For example: Without the strange getter-call (calendar.getTime()) which enforces update of internal calculation the result would be: 2014-07-06 (surely not what OP wants).
Therefore I recommend following other libraries to choose a generic approach compatible with different week definitions:
a) Java-8 (built-in library JSR-310 aka java.time):
LocalDate date = LocalDate.of(2014, 7, 26);
TemporalField dowField = WeekFields.ISO.dayOfWeek();
date = date.with(dowField, dowField.range().getMinimum());
System.out.println(date); // output: 2014-07-21
Note: Avoid code like date.with(DayOfWeek.MONDAY) because in that case the java.time-library cannot evaluate the underlying week rules which possibly deviate from ISO-8601 (here choosen: WeekFields.ISO, but it might also be WeekFields.SUNDAY_START).
b) my own library Time4J:
PlainDate date = PlainDate.of(2014, 7, 26);
date = date.with(Weekmodel.ISO.localDayOfWeek().minimized());
System.out.println(date); // output: 2014-07-21
c) If you know in advance that you only want ISO-8601-week-rules then you might also consider a simpler approach in Java-8 or instead its predecessor JodaTime:
// Java-8 applying ISO-8601-rules
LocalDate date = LocalDate.of(2014, 7, 26);
date = date.with(DayOfWeek.MONDAY);
// Joda-Time
LocalDate date = new LocalDate(2014, 7, 26);
date = date.dayOfWeek().withMinimumValue();
How do I add/subtract two time objects. I have two time objects (arrival and departure) in format of "yyyy/MMM/dd HH:mm:ss". I need to print the difference between departure and arrival time. I am generating time ad below:
public String getTime() {
Calendar currentDate = Calendar.getInstance();
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MMM/dd HH:mm:ss");
return formatter.format(currentDate.getTime());
}
Can I get time in mills and than format it when I needed to print ?
Take a look at Joda Time library.
You can easily subtract and add DateTime and find out interval easily :
// interval from start to end
DateTime start = new DateTime(2004, 12, 25, 0, 0, 0, 0);
DateTime end = new DateTime(2005, 1, 1, 0, 0, 0, 0);
Interval interval = new Interval(start, end);
something like this.....
public long getTimeDiff() throws Exception {
String arrival = "2011/Nov/10 13:15:24";
String departure = "2011/Jan/10 13:15:24";
SimpleDateFormat formatter = new SimpleDateFormat("yyyy/MMM/dd HH:mm:ss");
java.util.Date date1 = formatter.parse(arrival);
java.util.Date date2 = formatter.parse(departure);
return date2.getTime() - date1.getTime();
}
Convert them to date and then to long and subtract, that would give the time difference in milli seconds,
Date d1 = DateFormat.parse(time1);
Date d2 = DateFormat.parse(time2);
long diffInMilliSeconds = d1.getTime()-d2.getTime();
You can get time in milliseconds for both calendars using getTime method. When you can convert the result of subtraction to measure units that you need. If you're going to work with time/duration seriously when take a look at Joda library
Upd. You should call getTime twice. First object being returned is Date, when you call getTime on Date you get long value.
I would convert the two time/Date objects in milliseconds. Then i would subtract them (we are dealing with longs).
Then i would create a Date object from the resulting long value. After that you can construct a Calendar with Calendar.setDate(Date).
Regards!
Yes, start with your Dates and use getTime() to convert to milliseconds (or getTimeInMillis() for your Calendars). That give you long values you can subtract. That's the easy part.
Then you can convert these milliseconds into a readable format yourself. But it probably makes sense to use a packaged library to do it.
Some folks like the Joda library for these types of date calculations. I find Commons Lang is fantastic. It provides DateUtils which is useful if you find you want to perform calculations like rounding or truncating your dates to the nearest minute or hour etc. The part that will be most useful to you is the DurationFormatUtils class which gives you functions like formatDurationHMS to format into nice Hour:Minute:Second display and formatDurationWords to get text (fancy!) or other similar functions to easily format your milliseconds into a nicely human-readable format.
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.
I have current have two UI components used to specify a date and a time. Both components return java.util.Date instances representing the calendar date and time respectively. My question is:
What is the best way to combine these values to create a java.util.Date instance representing the date and time? I would like to avoid dependencies on Joda or other 3rd party libraries.
My current solution looks like this (but is there a better way?):
Date date = ... // Calendar date
Date time = ... // Time
Calendar calendarA = Calendar.getInstance();
calendarA.setTime(date);
Calendar calendarB = Calendar.getInstance();
calendarB.setTime(time);
calendarA.set(Calendar.HOUR_OF_DAY, calendarB.get(Calendar.HOUR_OF_DAY));
calendarA.set(Calendar.MINUTE, calendarB.get(Calendar.MINUTE));
calendarA.set(Calendar.SECOND, calendarB.get(Calendar.SECOND));
calendarA.set(Calendar.MILLISECOND, calendarB.get(Calendar.MILLISECOND));
Date result = calendarA.getTime();
public Date dateTime(Date date, Date time) {
return new Date(
date.getYear(), date.getMonth(), date.getDay(),
time.getHours(), time.getMinutes(), time.getSeconds()
);
}
you can corvert this deprecated code to Calendar obtaining your solution.
Then my answer is: no, you cannot do better without using joda
NB
jodatime soon will be standardized with JSR 310
I think you're approach is the best you're likely to get without using Joda time. A solution using SimpleDateFormats might use fewer lines, but is not really giving you any benefit.
Using Calendar
public Date dateTime(Date date, Date time) {
Calendar aDate = Calendar.getInstance();
aDate.setTime(date);
Calendar aTime = Calendar.getInstance();
aTime.setTime(time);
Calendar aDateTime = Calendar.getInstance();
aDateTime.set(Calendar.DAY_OF_MONTH, aDate.get(Calendar.DAY_OF_MONTH));
aDateTime.set(Calendar.MONTH, aDate.get(Calendar.MONTH));
aDateTime.set(Calendar.YEAR, aDate.get(Calendar.YEAR));
aDateTime.set(Calendar.HOUR, aTime.get(Calendar.HOUR));
aDateTime.set(Calendar.MINUTE, aTime.get(Calendar.MINUTE));
aDateTime.set(Calendar.SECOND, aTime.get(Calendar.SECOND));
return aDateTime.getTime();
}